JP5654783B2 - Optical receiver - Google Patents

Description

  The present invention relates to an optical receiver that receives an optical signal and converts it into an electrical signal.

  In recent years, with the progress of optical communication technology, optical transmission systems using optical cables have become widespread. According to this optical transmission system, relayless transmission of about several tens of kilometers can be performed, so that the transmission system can be easily widened. In general, this optical transmission system includes an optical transmitter including an optical transmitter disposed on the sender side and an optical receiver (optical network unit (ONU)) disposed on the receiver side using an optical cable. The long distance optical transmission line is used for connection.

  Then, the TV signal and the announcement broadcast signal are mixed on the transmitter side, the mixed electric signal is converted into an optical signal by the optical transmitter, and the optical signal is transmitted to the optical receiver via the optical transmission path. This optical receiver converts an optical signal into an electrical signal (RF signal) via a PD (Photo Diode), performs constant amplification by an amplifier, and outputs the signal to a TV receiver.

  In such an optical receiver, the output level of the RF signal changes in accordance with the input level of light. When the output level of the RF signal increases, the distortion performance deteriorates. When the output level of the RF signal decreases, the CNR ( (Carrier Per Noise Ratio) performance may deteriorate. Thus, an optical receiver provided with an AGC (AUTO GAIN CONTROL) circuit has been proposed in order to prevent fluctuations in the output level of the RF signal (see, for example, Patent Document 1).

JP 2009-111445 A

  However, in the conventional optical receiver, fluctuations in the output level of the RF signal are prevented by simply performing automatic gain adjustment by AGC based on light intensity detection, and thus have the following various problems.

  That is, if the user has expertise in gain adjustment, the gain of the amplifier may be optimized by manual adjustment by the user rather than automatic adjustment by AGC. Since no means for manual adjustment was provided, it was difficult to optimize the gain. Further, even if the means for manually adjusting is provided in the optical receiver, the conventional optical receiver has not been provided with means for allowing the user to grasp the output level of the RF signal. In order for the user to grasp the output level of the RF signal, it is necessary to connect an external device such as a level measuring device to the optical receiver.

  In addition, since the optical receiver is normally operated with multiple waves and the level of the RF signal is the total output level of the multiple waves, the optimum value of the level of the RF signal also changes when the wave number changes. However, in the conventional optical receiver, when the automatic gain adjustment by AGC is performed, the output level of the RF signal is adjusted by simply detecting the intensity of light regardless of the wave number, so that the gain should be optimized. It was difficult. Further, even if a means for performing manual adjustment is provided in the optical receiver, the conventional optical receiver does not have means for allowing the user to grasp the wave number. It was difficult to optimize the gain.

  Also, the level of the RF signal may vary depending on the frequency band and modulation method. However, in the conventional optical receiver, when automatic gain adjustment by AGC is performed, regardless of the frequency band and modulation method, Since the level of the RF signal was uniformly adjusted, it was difficult to optimize the gain. In addition, even if a means for performing manual adjustment is provided in the optical receiver, the conventional optical receiver has not been provided with means for allowing the user to grasp the frequency band and the modulation method. It has been difficult to optimize the gain according to the frequency band and modulation method.

  The present invention has been made in view of the above, and can easily and accurately perform manual gain adjustment of the level of the RF signal, and can optimally adjust the level of the RF signal according to the wave number, Alternatively, an object of the present invention is to provide an optical receiver that can optimally adjust the level of an RF signal according to a frequency band and a modulation method.

In order to solve the above-described problems and achieve the object, the optical receiver according to claim 1 is an optical receiver that receives an optical signal and converts the optical signal into an electric signal, and the optical signal includes a plurality of waves. An optical signal carrying an electrical signal, a photodiode for converting the optical signal into the electrical signal, and any state from being output by the photodiode until being output to the outside of the optical receiver Detecting means for outputting a detection value corresponding to the level of the electric signal in the signal, calculating the level of the electric signal based on the detection value of the detection means, and based on the calculated level of the electric signal, the optical receiver Control means for performing predetermined control for enabling adjustment of the level of the electrical signal output to the outside of the signal, and wave number storage means for storing the wave numbers of the plurality of waves, wherein the control means comprises the detection Means detection The electric signal level calculated for each wave is calculated based on the electric signal level calculated based on the wave number and the wave number stored in the wave number storage means, and the calculated electric signal level for each wave is calculated. On the basis of the above, predetermined control for enabling adjustment of the level of the electric signal for each wave is performed .

The optical receiver according to claim 2 is the optical receiver according to claim 1 , wherein the wave number storage unit stores the wave numbers of the plurality of waves for each band and modulation method of the electric signal, and for the control. The means is based on the level of the electrical signal calculated based on the detection value of the detection means and the wave number for each band and the modulation method stored in the wave number storage means and for each band and each modulation method. The level of the electric signal for each wave is calculated.

According to a third aspect of the present invention , in the optical receiver according to the first or second aspect , the conversion information for converting the detection value of the detection means into the level of an electric signal is converted into frequency characteristics of the detection means. Conversion information storage means for storing for each different band, the detection means outputs a detection value according to the frequency characteristic of the detection means, the detection value according to the level of the electrical signal, and the control The means acquires the conversion information of the band corresponding to the frequency of the electrical signal from the conversion information stored in the conversion information storage means, and based on the acquired conversion information, the detection value of the detection means is obtained. The level of the electric signal is calculated by conversion, and the predetermined control is performed based on the calculated level of the electric signal.

The optical receiver according to claim 4 is the optical receiver according to claim 3 , wherein the conversion information storage unit stores the conversion information for each modulation method of the electric signal, and the detection unit includes: A detection value corresponding to the level of the electric signal, and a detection value corresponding to the modulation method of the electric signal is output, and the control means includes the conversion information stored in the conversion information storage means. the acquired conversion information, based on the acquired conversion information to calculate the level of the electrical signal by converting the detected values of said detecting means, the level of the calculated electric signal corresponding to the modulation scheme of the electrical signal Based on the above, the predetermined control is performed.

The optical receiver according to claim 5 is the optical receiver according to any one of claims 1 to 4 , wherein the control unit performs an averaging process on a detection value of the detection unit, and performs the averaging process. The level of the electric signal is calculated based on the processed detection value.

An optical receiver according to claim 6 is the optical receiver according to claim 1, further comprising a plurality of signal lines for transmitting the electric signal output from the photodiode for each frequency band, and for each signal line. The detection means is provided.

8. The optical receiver according to claim 7 , wherein the optical receiver receives an optical signal and converts the optical signal into an electric signal, a photodiode for converting the optical signal into the electric signal, and an output from the photodiode. Detecting means for outputting a detected value corresponding to the level of the electric signal in any state from when the optical signal is output to the outside of the optical receiver, and based on the detected value of the detecting means, the level of the electric signal And a control means for performing predetermined control to enable adjustment of the level of the electrical signal output to the outside of the optical receiver based on the calculated level of the electrical signal, and output from the photodiode A plurality of signal lines for transmitting the electrical signals for each frequency band; and connection means for selectively connecting the detection means to the plurality of signal lines.

The optical receiver according to claim 8 is the optical receiver according to any one of claims 1 to 7 , wherein the optical receiver outputs from the photodiode until it is output to the outside of the optical receiver. Manual gain adjusting means for manually adjusting the gain of the electrical signal in such a state.

The optical receiver according to claim 9 is the optical receiver according to any one of claims 1 to 8 , wherein the output is performed by the photodiode based on the level of the electric signal calculated by the control means. And automatic gain adjusting means for adjusting the gain of the electric signal in any state from when the optical signal is output to the outside of the optical receiver.

An optical receiver according to a tenth aspect is the optical receiver according to the ninth aspect , wherein the detection means is provided on the upstream side of the automatic gain adjustment means.

An optical receiver according to an eleventh aspect is the optical receiver according to any one of the first to tenth aspects, wherein the optical receiver outputs from the photodiode until it is output to the outside of the optical receiver. An electric signal frequency unit acquiring means for acquiring an electric signal for each frequency from the electric signal in such a state and outputting the electric signal to the detecting means is provided.

An optical receiver according to a twelfth aspect is the optical receiver according to the first or second aspect , further comprising compensation means for compensating for frequency characteristics of the detection means.

An optical receiver according to a thirteenth aspect of the present invention is the optical receiver according to any one of the first to twelfth aspects, further comprising display means for displaying the level of the electric signal calculated by the control means. It is.

According to the optical receiver of the first aspect, the level of the electric signal is calculated based on the detection value of the detection means, and the electric signal output to the outside of the optical receiver is calculated based on the level of the electric signal. Since the predetermined control for enabling the level adjustment is performed, the level of the electric signal can be easily and accurately adjusted.
In addition, since predetermined control for adjusting the level of the electric signal for each wave is performed, it is possible to easily and accurately optimize the gain according to the wave number even during multi-wave operation. Become.

According to the optical receiver according to claim 2 , since the level of the electric signal for each wave is calculated based on the level of the electric signal, the band, and the wave number for each modulation method, Even if the level of the electric signal for each wave is different, the level of the electric signal for each band and modulation method can be calculated easily and accurately.

According to the optical receiver of claim 3 , since the level of the electrical signal is calculated by converting the detection value of the detection means based on the conversion information corresponding to the frequency of the electrical signal, the frequency characteristic of the detection means Even if the level of the detected value fluctuates due to this, the level of the electric signal can be calculated easily and accurately.

According to the optical receiver according to claim 4, based on the conversion information corresponding to the modulation scheme of the electric signals, since the calculated level of the electrical signal by converting the detected values of the detection means, the modulation of the electrical signal Even when the level of the detected value varies depending on the method, the level of the electric signal can be calculated easily and accurately.

According to the optical receiver of the fifth aspect , since the predetermined control is performed based on the result of the averaging process on the detection value of the detection means, the level of the detection value of the detection means varies depending on the amplitude fluctuation of the electric signal. Even in this case, the level of the electric signal can be calculated easily and accurately.

According to the optical receiver of the sixth aspect , since the detection means is provided for each signal line for transmitting the electric signal for each frequency band, the level detection can be performed for each frequency band, and one wave for each frequency band. Even when the level of each electric signal is different, the level of the electric signal for each frequency band can be calculated easily and accurately.

According to the optical receiver of claim 7 , the level of the electric signal is calculated based on the detection value of the detection means, and the electric signal output to the outside of the optical receiver is calculated based on the level of the electric signal. Since the predetermined control for enabling the level adjustment is performed, the level of the electric signal can be easily and accurately adjusted.
In addition, since a plurality of signal lines for transmitting electrical signals by frequency band and a connection means for selectively connecting the detection means to the plurality of signal lines are provided, the common detection means is used for the plurality of signal lines. The level of the electric signal can be detected, and the optical receiver can be configured simply and inexpensively as compared with the case where the detection means is provided in each of the plurality of signal lines.

According to the optical receiver of the eighth aspect , since the manual gain adjusting means for manually adjusting the level of the electric signal is provided, the level of the electric signal can be manually adjusted to the optimum value.

According to the optical receiver of the ninth aspect , since the automatic gain adjusting means for adjusting the gain of the electric signal is provided, the level of the electric signal can be automatically adjusted to the optimum value.

According to the optical receiver of the tenth aspect , since the detecting means is provided on the upstream side of the automatic gain adjusting means, the gain is adjusted based on the output level of the electrical signal detected on the upstream side of the automatic gain adjusting means. The gain adjustment result is not reflected in the detection of the output level of the electrical signal, and so-called feedback control is not performed, so that the level of the electrical signal can be stabilized.

According to the optical receiver of the eleventh aspect , since the electric signal frequency unit acquisition means for acquiring the electric signal for each frequency and outputting the electric signal to the detection means is provided, the level of the electric signal is detected for each frequency. It is possible to detect the level of the electric signal for each wave easily and accurately.

According to the optical receiver of the twelfth aspect , since the compensation means for compensating the frequency characteristic of the detection means is provided, the level of the electric signal can be flat over a wide band, and the frequency of the detection means Since there is no need to hold a plurality of pieces of conversion information according to the characteristics, the level of the electric signal can be easily and accurately detected without using a plurality of pieces of conversion information.

According to the optical receiver of the thirteenth aspect , since the display means for displaying the electric signal level calculated by the control means is provided, the user can easily confirm the electric signal level via the display means. It becomes possible.

It is a block diagram of the optical receiver which concerns on Embodiment 1 of this invention. It is a block diagram of a reception control part. It is a figure which shows the structural example of a parameter setting table. It is a figure which shows the structural example of a conversion graph. It is a flowchart of a level adjustment process. It is a block diagram of the optical receiver which concerns on Embodiment 2 of this invention. It is a block diagram of the optical receiver which concerns on Embodiment 3 of this invention. It is a block diagram of the optical receiver which concerns on Embodiment 4 of this invention. It is a block diagram of the optical receiver which concerns on Embodiment 5 of this invention. It is a block diagram of the optical receiver which concerns on Embodiment 6 of this invention. It is a block diagram of the optical receiver which concerns on Embodiment 7 of this invention.

  Hereinafter, embodiments of an optical receiver according to the present invention will be described in detail with reference to the accompanying drawings. However, the present invention is not limited by these embodiments.

[Embodiment 1]
First, Embodiment 1 of the present invention will be described. In this embodiment, the level of the electrical signal is calculated based on the detection value of the detection means, and the level of the electrical signal output to the outside of the optical receiver can be adjusted based on the calculated level of the electrical signal. This is a basic form for performing the predetermined control.

(Constitution)
First, the configuration of the optical receiver according to the first embodiment will be described. FIG. 1 is a block diagram of an optical receiver according to the first embodiment. The optical receiver 1 receives optical signals in each frequency band of CATV (including FM, VHF, and UHF), BS, and CS and converts them into RF signals. The PD 10, the amplifier 11, and the AGC circuit ( (Optical AGC) 12, separator 13, first signal line 14, second signal line 15, mixer 16, branching device 17, and output terminal 18 are connected as shown in the figure. The first signal line 14 includes an amplifier 19, a GC (Gain Control) 20, and an amplifier 21, and the second signal line 15 includes an amplifier 22, a GC 23, and an amplifier 24. A detector 25 is connected to the branching device 17, and a reception control unit 30 is connected to the detector 25.

  The PD 10 is a photoelectric conversion unit that receives an optical signal transmitted through an optical transmission path (not shown) and photoelectrically converts the optical signal into an electrical signal (hereinafter referred to as an RF signal). The amplifier 11 is an amplification unit that amplifies the RF signal converted by the PD 10. The AGC circuit 12 is automatic gain adjustment means for performing automatic gain adjustment of the RF signal amplified by the amplifier 11. The separator 13 is a demultiplexing unit that frequency-separates the RF signal output from the AGC circuit 12 into a CATV signal and a BS / CS signal. The first signal line 14 is a line that amplifies the CATV signal demultiplexed by the separator 13, and the second signal line 15 is a line that amplifies the BS / CS signal demultiplexed by the separator 13, Amplifiers 19 and 22 are amplification means for amplifying CATV signals or BS / CS signals, and GC20 and 23 are automatic gain adjustments for gain adjustment of CATV signals or BS / CS signals amplified by amplifiers 19 and 22 with a fixed gain. The means and amplifiers 21 and 24 are amplification means for amplifying the CATV signal or the BS / CS signal whose gain is adjusted by the GC 20 or 23. The mixer 16 is a multiplexing unit that mixes the CATV signal amplified on the first signal line 14 and the BS / CS signal amplified on the second signal line 15. The branching unit 17 is a branching unit that branches the RF signal mixed by the mixer 16. The output terminal 18 is output means for outputting the RF signal branched by the branching device 17 to the outside.

  The detector 25 is a detector that outputs a detection value corresponding to the level of the RF signal in any state from the output from the PD 10 to the output from the optical receiver 1. Detection means for outputting a detection value corresponding to the signal level of the RF signal branched by the device 17. The detector 25 can be configured in the same manner as a known detector.

(Configuration-reception control unit)
The reception control unit 30 is a reception control unit that controls each unit of the optical receiver 1, calculates the level of the RF signal based on the detection value of the detector 25, and based on the calculated level of the RF signal, It is a control means for performing predetermined control for enabling adjustment of the level of the RF signal output to the outside of the optical receiver 1. FIG. 2 is a block diagram of the reception control unit 30. As shown in FIG. 2, the reception control unit 30 includes a control unit 31, a storage unit 32, an input unit 33, and an output unit 34.

  The control unit 31 is a control unit that controls each unit of the reception control unit 30. For example, an operational amplifier or CPU, various programs interpreted and executed on the CPU (control programs such as an OS, various processing procedures, and the like). And the internal memory for storing the required program and required data.

  The storage unit 32 is a storage unit that stores various types of information necessary for various types of processing in the reception control unit 30, and includes, for example, a flash memory or other recording medium. Information stored in the storage unit 32 will be described later. Although not shown, a level adjustment program is installed in the storage unit 32. This program is substantially written in the storage unit 32 by a writing device (not shown), thereby substantially configuring each unit of the control unit 31.

  The input unit 33 is an input unit for the user to input various types of information to the reception control unit 30. For example, although not illustrated, the input unit 33 includes a plurality of volumes and operation buttons. Alternatively, the input unit 33 may be a unit that receives an input from the outside of the optical receiver 1 and is configured as a communication interface for performing remote control by TELNET, SNMP, or the like.

  The output unit 34 is an output unit that outputs various types of information to the user. In particular, the output unit 34 is a display unit that displays and outputs various types of information to the user, and includes, for example, a liquid crystal panel. . Alternatively, the output unit 34 may be an output unit that outputs sound and signals to the outside of the optical receiver 1. For example, the output unit 34 may be configured as a speaker, configured as a voltage output check terminal, or may be configured as TELNET or SNMP. It is configured as a communication interface for performing remote monitoring by, for example.

(Configuration-reception control unit-stored information)
Next, information stored in the storage unit 32 will be described. Here, the storage unit 32 stores a parameter setting table, a conversion graph, and other setting information.

  The parameter setting table is a table in which various parameters necessary for various processes in the reception control unit 30 are set. FIG. 3 shows a configuration example of the parameter setting table. This parameter setting table includes a plurality of parameters set for each transmission frequency band. Here, the transmission frequency band is divided into “CATV” and “BS · CS”, and “CATV” is further divided into “analog wave” and “digital wave”.

  The parameters are “wave number”, “alarm upper limit threshold”, “alarm lower limit threshold”, “target output level”, and “target output level automatic adjustment flag”. The parameter “wave number” is a parameter for setting the number of broadcast waves included in the RF signal (hereinafter, wave number). In the example of FIG. 3, “11” is the wave number of the CATV analog wave, and the CATV digital wave is “80” is set as the wave number of “36”, and “36” is set as the wave number of BS / CS.

  The parameter “alarm upper limit threshold value” is a parameter for setting a threshold value (hereinafter referred to as an alarm upper limit threshold value) that is an upper limit of the output level of the RF signal. The maximum value that satisfies the standard is set. In the example of FIG. 3, “+5 (dBm)” is set as the alarm upper limit threshold.

  The parameter “alarm lower limit threshold” is a parameter for setting a threshold (hereinafter referred to as an alarm lower limit threshold) as a lower limit of the output level of the RF signal. As this alarm lower limit threshold, for example, the CNR of the optical receiver 1 is The minimum value that satisfies the standard is set. In the example of FIG. 3, “−5 (dBm)” is set as the alarm lower limit threshold value.

  The parameter “target output level” is a parameter for setting a target value of the output level of the RF signal (hereinafter, target output level). In the example of FIG. 3, the target output level per one analog wave of CATV is set. “90”, “80” as the CATV digital wave target output level, and “80” (unit is dBμ) as the target output level per BS / CS wave, respectively.

  The parameter “target output level automatic adjustment flag” is information (hereinafter referred to as target output level automatic adjustment flag) indicating whether or not the automatic adjustment for setting the output level of the RF signal to the target output level is continued. Here, when the target output level automatic adjustment flag = 0, automatic adjustment is not continued, and when the target output level automatic adjustment flag = 1, automatic adjustment is continued.

  As the setting unit of the alarm upper threshold, alarm lower threshold, target output level, and target output level automatic adjustment flag, setting for the total output of each wave or setting for the output of each individual wave is possible. it can. In the example of FIG. 3, the alarm upper limit threshold, the alarm lower limit threshold, and the target output level automatic adjustment flag are set for the total output of each wave, and the target output level is set for each wave individually output. Settings are made for this. Here, as the alarm upper limit threshold and the alarm lower limit threshold, a threshold for the total output of all the waves in the CATV band and the BS / CS band is set, and the target output level is set for each analog wave in the CATV band. It is assumed that the target output level for output is set.

  Next, the conversion graph stored in the storage unit 32 will be described. This conversion graph is a table composed of conversion information for converting the output value from the detector 25 into the output level of the RF signal. FIG. 4 shows a configuration example of the conversion graph. In this conversion graph, the horizontal axis indicates the output value from the detector 25, the vertical axis indicates the output level of the RF signal, and a graph showing the correspondence between these is plotted.

  Here, the detector 25 usually has f characteristics (frequency characteristics), and even if the output level of the detected RF signal is the same, it is possible to output different output values depending on the transmission frequency of the RF signal. There is sex. For this reason, if the conversion is performed using only one conversion graph for RF signals of all transmission frequencies, the f characteristic is not reflected, and there is a possibility that accurate conversion cannot be performed. Therefore, in the present embodiment, a conversion graph corresponding to each of a plurality of transmission frequencies included in the transmission frequency that can be taken by the RF signal is stored in the storage unit 32, and the transmission frequency closest to the transmission frequency of the RF signal is stored. The output value from the detector 25 is converted into the output level of the RF signal based on the conversion graph corresponding to.

  Further, when the modulation signal of the RF signal is a digital signal, the detection value by the detector 25 may be different depending on the modulation method even if the output level of the RF signal is the same. Therefore, in the present embodiment, a conversion graph corresponding to each of a plurality of modulation methods (here, analog and digital) of the RF signal is stored in the storage unit 32, and conversion corresponding to the modulation method of the RF signal is performed. Based on the graph, the output value from the detector 25 is converted into the output level of the RF signal.

  More specifically, the conversion graph is roughly divided into a CATV band and a BS / CS band according to the transmission frequency that can be taken by the RF signal, and the conversion graph for the CATV band is for analog and digital use. And one or a plurality of conversion graphs are stored in each. That is, the storage unit 32 functions as conversion information storage means for storing conversion information for converting the detection value by the detector 25 into the level of the RF signal for each band in which the frequency characteristics of the detector 25 are different.

  Other setting information stored in the storage unit 32 includes a transmission frequency band and a modulation method. The transmission frequency band is the frequency band of the RF signal. The modulation method is a modulation method of an RF signal, and here is either analog modulation or digital modulation.

  Various types of information stored in the storage unit 32 in this way are set by the user via the input unit 33 prior to level adjustment processing described later. Further, the user can change these information at an arbitrary timing via the input unit 33.

  Alternatively, a part of the information may be calculated by the control unit 31 of the reception control unit 30 and set in the storage unit 32. For example, when the user changes the wave number via the input unit 33 in the information configuring the parameter setting table of FIG. 3, the alarm upper limit threshold, the alarm lower limit threshold, or the target output level for the wave number before the change is changed. The control unit 31 may automatically calculate and change the alarm upper limit threshold value or the alarm lower limit threshold value based on the ratio or difference and the wave number after the change. For example, when the wave number = 80 and the alarm upper limit threshold = −5 dBm before the change, and when the wave number is changed to 72, the alarm upper limit threshold after the change = −5 + 10 log (72/80) = − 5.5 dBm And The target output level is basically constant, but the target output level may be changed based on the wave number after the change.

(processing)
Next, the level adjustment process performed in the reception control unit 30 will be described. Since the control and processing of the optical receiver 1 other than the level adjustment processing can be performed in the same manner as the conventional optical receiver, description thereof is omitted. FIG. 5 is a flowchart of the level adjustment process (hereinafter, steps are abbreviated as “S”). It is assumed that this level adjustment process is repeatedly performed by the control unit 31 after the optical receiver 1 is started unless otherwise specified. Prior to this processing, it is assumed that the storage unit 32 stores a parameter setting table including parameters set by the parameter setting processing described above and a conversion graph.

  First, the control unit 31 specifies the transmission frequency band and modulation method of the RF signal (SA1). Specifically, the control unit 31 refers to the setting information stored in the storage unit 32, and specifies the transmission frequency band and the modulation method that are most dominant in the output level detection of the RF signal. In the example of FIG. 3, the total RF output level of the CATV analog wave, CATV digital wave, and BS · CS is calculated by the target output level (dBμ) +10 log (wave number), and becomes 100.4 dBμ, 99.0 dBμ, and 95.6 dBμ, respectively. . Accordingly, since the level of the CATV analog wave is the largest and most dominant, the control unit specifies the transmission frequency band as the CATV band and the modulation method as analog modulation.

  Next, the control unit 31 specifies an optimum conversion graph for converting the output value from the detector 25 into the output level of the RF signal (SA2). Specifically, which one of the conversion graphs for the CATV band and the BS / CS band is to be selected from the plurality of conversion graphs stored in the storage unit 32 based on the transmission frequency band specified by SA1. decide. When it is determined that the conversion graph for the CATV band should be selected, either the analog conversion graph or the digital conversion graph is selected from the conversion graph for the CATV band based on the modulation method specified in SA1. From the conversion graph thus determined, one conversion graph for the band closest to the transmission frequency band specified by SA1 is selected. Alternatively, when it is determined that a conversion graph for the BS / CS band should be selected, one conversion graph for the band closest to the transmission frequency band specified by SA1 is selected from the conversion graph for the BS / CS band. Select one. By selecting the conversion graph in this way, it is possible to perform conversion using a conversion graph having characteristics matching the transmission frequency band and modulation method of the RF signal, and the detection accuracy of the output level of the RF signal can be improved. It becomes possible.

  The control unit 31 averages the output value from the detector 25 (SA3). In other words, the level of the output value from the detector 25 (specifically, the output voltage value) may vary depending on the modulation method of the RF signal. In particular, when the modulation method is analog modulation, an image is transmitted by the amplitude fluctuation of the RF signal. Therefore, when the response speed of the detector 25 is fast, the level of the output value from the detector 25 is the amplitude fluctuation. May vary due to Therefore, in the present embodiment, the adverse effect due to the fluctuation of the level of the output value from the detector 25 is reduced by averaging the output value from the detector 25. For example, the control unit 31 continuously acquires the output value from the detector 25 for a predetermined time (for example, several tens to several hundreds of milliseconds), calculates the sum of the acquired output values, and calculates the calculated sum. By dividing by the number of acquisitions, the average output value is calculated, and the calculated average output value is used as the output value from the detector 25. Such averaging processing may be performed by hardware as well as by software. For example, an LPF (Low Pass Filter) is connected to the output of the detector 25 to perform averaging processing, and the LPF The output may be used as the output value from the detector 25 on the rear stage side.

  Next, the control unit 31 converts the output value from the detector 25 averaged in SA3 into the output level of the RF signal using the conversion graph specified in SA2 (SA4). Then, the control unit 31 displays the output level of the RF signal thus calculated on the liquid crystal panel in the output unit 34 (SA5). By performing such display, the user can easily and accurately grasp the output level of the RF signal.

  Thereafter, the control unit 31 calculates and displays the output level of the RF signal per wave (SA6). Specifically, the control unit 31 acquires the wave number corresponding to the combination of the transmission frequency band of the RF signal specified by SA1 and the modulation method from the parameter setting table of the storage unit 32, and based on the acquired wave number, SA4 The output level of the RF signal per wave is calculated by dividing the output level of the RF signal converted in (1). For example, in the example of FIG. 3, when the output level of the RF signal converted by SA4 is −5 dBm, the output level of the RF signal per wave is 90.3 dBμ for CATV analog waves, CATV digital waves and BS · CS. Is calculated to be 80.3 dBμ. (Specifically, in FIG. 3, the wave number of 90 dBμ is 11 and the wave number of 80 dBμ is 80 + 36, and the 90 dBμ1 wave corresponds to 10 waves of 80 dBμ, so the 90 dBμ × 11 wave becomes 80 dBμ × 110 waves. 3, 80 dBm is 110 + 80 + 36 = 226. From this, the output level per wave is -5 dBm-10 log (226) = -28.5 dBm for CATV digital waves and BS / CS waves. −28.5 + 108.8 = 80.3 dBμ, and the CATV analog wave becomes +10 dB and becomes 90.3 dBμ). Then, the control unit 31 displays the output level of the RF signal per wave for each band calculated in this way on the liquid crystal panel in the output unit 34 (SA6). By performing such display, the user can easily and accurately grasp the output level of the RF signal per wave.

  Next, the control unit 31 compares the output level of the RF signal calculated in SA6 with the alarm upper limit threshold stored in the parameter setting table of the storage unit 32, and the output level of the RF signal is equal to or higher than the alarm upper limit threshold. In this case (SA7, Yes), after outputting an overlevel alarm from the output unit 34 (SA8), the process proceeds to SA9, and when the output level of the RF signal is not equal to or higher than the alarm upper limit threshold (SA7, No), The process proceeds to SA9 without outputting an overlevel alarm from the output unit 34. The over-level alarm is an alarm output for notifying the user that the output level of the RF signal is equal to or higher than the alarm upper limit threshold, and its specific output form is arbitrary as long as this purpose can be achieved. For example, a text indicating the fact is blinked on the liquid crystal panel as the output unit 34, or a predetermined alarm sound is output from a speaker as the output unit 34 (the output form of a low level alarm described later is also the same). By outputting such an overlevel alarm, the user can easily and accurately grasp that the distortion of the optical receiver 1 deviates from the standard because the output level of the RF signal is too high. It becomes possible.

  Further, the control unit 31 compares the output level of the RF signal converted in SA4 with the alarm lower limit threshold stored in the parameter setting table of the storage unit 32, and the output level of the RF signal is equal to or lower than the alarm lower limit threshold. In the case (SA9, Yes), after outputting a low level alarm from the output unit 34 (SA10), the process proceeds to SA11, and when the output level of the RF signal is not less than or equal to the alarm lower limit threshold (SA9, No), The process proceeds to SA11 without outputting a low level alarm from the output unit 34. By outputting such a low level alarm, the user can easily and accurately grasp that the CNR of the optical receiver 1 deviates from the standard because the output level of the RF signal is too small. It becomes possible.

  Next, the control unit 31 performs gain control based on the target output level (SA11). Specifically, the control unit 31 acquires the wave number and the target output level corresponding to the combination of the transmission frequency band of the RF signal specified by SA1 and the modulation method from the parameter setting table of the storage unit 32, and the wave number and The target output level of the RF signal output level is calculated by dividing the target output level from each other. For example, in the example of FIG. 3, since the signal wave of the target output level 90 dBμ is 11 waves and the signal wave of 80 dBμ is 80 + 36 = 116 waves, the target output level of the RF signal is 80 + 10 log (11 × 10 + 116) = 103.5 dBμ. Become. Then, the control unit 31 automatically adjusts the gains of the GCs 20 and 23 so that the output level of the RF signal becomes the calculated target output level.

  Thereafter, the control unit 31 determines whether or not to continue the automatic adjustment of the output level of the RF signal (SA12). That is, the control unit 31 acquires the target output level automatic adjustment flag from the parameter setting table of the storage unit 32, and when the target output level automatic adjustment flag = 0, the automatic adjustment is not continuously performed, When the target output level automatic adjustment flag = 1, it is determined that the automatic adjustment is continuously performed.

  If the control unit 31 determines that automatic adjustment is not to be continued (SA12, No), the control unit 31 ends the level adjustment process without fixing the GC20 and 23 settings to the gain adjusted in SA11. To do. In this case, when the level adjustment process is started again thereafter and the process of SA11 is performed, the gains of the GCs 20 and 23 are adjusted again as necessary. Thereafter, each time the level adjustment process is activated and the process of SA11 is repeated, the gains of the GCs 20 and 23 are automatically adjusted according to the conditions at that time. As described above, the case where the automatic adjustment of the gain of the GCs 20 and 23 is selected is as follows. That is, when the level of the RF signal input to the transmission system at the subsequent stage of the optical receiver 1 is determined, it is selected to always automatically adjust the gains of the GCs 20 and 23 so that the level becomes the level. .

  On the other hand, if it is determined that the automatic adjustment is to be continued (SA12, Yes), the control unit 31 fixes the settings of GC20 and 23 to the gain adjusted in SA11 (SA13), and then performs level adjustment processing. Exit. In this case, even when the level adjustment process is subsequently started again and the process of SA11 is performed, when the power of the optical receiver 1 is turned OFF / ON, or by other predetermined operation Until the restart of the gain adjustment is instructed, the gains of the GCs 20 and 23 are fixed without being changed. The following cases correspond to cases where fixing the gains of the GCs 20 and 23 is selected as described above. That is, there is a possibility that the transmission wave number may increase or decrease in the optical transmission system. If the automatic adjustment of the GCs 20 and 23 is continued up to such a case, the RF output power becomes constant, but the RF output level per wave is reduced. In order to prevent such a situation, it is selected that the gains of the GCs 20 and 23 are fixed.

  However, the gain adjustment from SA11 to SA13 may be omitted. In this case, the user manually adjusts the GC20, 23 via the input unit 33 while referring to the output level of the RF signal displayed at SA5 or SA6. You may make it adjust so that a gain may become an optimal value. That is, a volume as a manual gain adjusting means for manually adjusting the level of the RF signal output to the outside of the optical receiver 1 is provided in place of the GC 20, 23, or before or after the GC 20, 23. The user may manually adjust the level of the RF signal through the volume while referring to the level of the RF signal detected by the detector 25 and output by the output unit 34. At this time, reference information such as the target output level stored in the storage unit 32 is also output to the output unit 34 so that the user can make adjustments with reference to this reference information. Good. According to such a configuration, the level of the RF signal can be manually adjusted to an optimum value.

(Effect of Embodiment 1)
As described above, according to the first embodiment, the level of the RF signal is calculated based on the detection value of the detector, and the RF output to the outside of the optical receiver 1 based on the level of the RF signal. Since predetermined control for enabling adjustment of the signal level is performed, the level of the RF signal can be adjusted easily and accurately.
In addition, since predetermined control for adjusting the level of the RF signal for each wave is performed, it is possible to easily and accurately optimize the gain according to the wave number even during multi-wave operation. Become.
Further, by dividing the RF signal level by the wave number for each band and modulation method, the level of the RF signal for each wave is calculated, so the RF signal level for each wave is calculated for each band and modulation method. Even in different cases, it is possible to easily and accurately calculate the RF signal level for each band and modulation method.
Further, since the level of the RF signal is calculated by converting the detection value of the detector 25 based on the conversion information corresponding to the frequency of the RF signal, the level of the detection value varies depending on the frequency characteristics of the detector 25. Even so, the level of the RF signal can be easily and accurately calculated.
In addition, since the level of the RF signal is calculated by converting the detection value of the detector 25 based on the conversion information corresponding to the modulation method of the optical signal, the level of the detection value varies depending on the modulation method of the optical signal. Even so, the level of the RF signal can be easily and accurately calculated.
In addition, since predetermined control is performed based on the result of the averaging process on the detection value of the detector 25, even if the level of the detection value of the detector 25 varies due to fluctuations in the amplitude of the RF signal, The level can be calculated easily and accurately.
When a volume for manually adjusting the RF signal level is provided, the RF signal level can be manually adjusted to an optimum value.
In addition, since the GCs 20 and 23 for adjusting the gain of the RF signal are provided, the level of the RF signal can be automatically adjusted to the optimum value.
In addition, since the output unit 34 that displays the level of the RF signal is provided, the user can easily check the level of the RF signal.

[Embodiment 2]
Next, a second embodiment of the present invention will be described. In this form, a plurality of signal lines for transmitting the RF signal output from the photodiode for each frequency band are provided, and a detecting means is provided for each signal line. However, unless otherwise specified, the configuration and processing are the same as those of the first embodiment, and the same configurations and processing as those of the first embodiment are denoted by the same reference numerals as those used in the first embodiment. The description is omitted by attaching.

(Constitution)
FIG. 6 is a block diagram of an optical receiver according to the second embodiment. The optical receiver 2 is configured in substantially the same manner as the optical receiver 1 according to the first embodiment, but the first signal line 40 has a branching device 42 and the second signal line 41 has a branching device. 43, a detector 44 is connected to the branching device 42, a detector 45 is connected to the branching device 43, and a reception control unit 50 common to the detector 44 and the detector 45 is illustrated. Are different in that they are connected. The branching units 42 and 43 are branching means for branching the RF signal amplified by the amplifiers 21 and 24. The detectors 44 and 45 are detection means for outputting a detection value corresponding to the signal level of the RF signal branched by the branching units 42 and 43. The reception control unit 50 is a reception control unit that controls each unit of the optical receiver 2, and is configured in the same manner as the reception control unit 30 of the first embodiment except for a configuration specifically described.

  The parameter setting table stored in the storage unit 32 of the reception control unit 50 is configured in substantially the same manner as the parameter setting table according to the first embodiment, but each of the alarm upper limit threshold and the alarm lower limit threshold is set in the CATV band. And is different for each BS / CS band. Further, the conversion graph stored in the storage unit 32 is configured in substantially the same manner as the conversion graph according to the first embodiment. However, as the conversion graph of each modulation method, the conversion graph is further provided for each CATV band and BS / CS band. In each of the CATV band and the BS / CS band, conversion graphs corresponding to each of a plurality of transmission frequencies included in the transmission frequencies that can be taken by the RF signal are stored. Each of these conversion graphs is created in consideration of the f characteristic of the mixer 16. That is, when the detection values of the detectors 44 and 45 connected to the upstream side of the mixer 16 are converted into the output level of the RF signal, this output level is output when output from the output terminal 18 via the mixer 16. Although it is preferable to match the level, since the output level of the RF signal fluctuates in accordance with the transmission frequency band when mixed by this mixer 16, it is converted into a value including this fluctuation amount. Each conversion graph is created for each transmission frequency.

(processing)
Using the optical receiver 2 configured in this manner, level adjustment processing is performed in substantially the same manner as in the first embodiment, but the detection and display of the output level of the RF signal is performed in the CATV band and the BS / CS band, respectively. Done. That is, in the flowchart of FIG. 5, in SA2, the conversion graph for converting the output value from the detector 44 into the output level of the RF signal is selected from the conversion graph of the CATV band, and the output from the detector 45 is selected. The conversion graph for converting the value into the output level of the RF signal is selected from the conversion graph of the BS / CS band. In SA3, the output value from the detector 44 and the output value from the detector 45 are individually averaged. In SA4, the output value from the detector 44 averaged in SA3 is converted into the output level of the RF signal in the CATV band using the conversion graph specified in SA2, and the detector 45 averaged in SA3. Is converted into the output level of the BS / CS band RF signal using the conversion graph specified in SA2. The output level calculated in this way is individually displayed on the liquid crystal panel in the CATV band and the BS / CS band, and the total value is also displayed on the liquid crystal panel. In SA6, the output level of the RF signal per wave is individually performed in the CATV band and the BS / CS band, and the result is individually displayed on the liquid crystal panel, and the total value is also the liquid crystal. Displayed on the panel. Further, in SA7 to SA11, alarm output by comparison with the alarm upper limit threshold and the alarm lower limit threshold is individually performed in the CATV band and the BS / CS band.

(Effect of Embodiment 2)
As described above, according to the second embodiment, the detectors 44 and 45 are provided in each of the first signal line 40 and the second signal line 41 for transmitting the RF signal for each frequency band. The level detection can be performed every time, and even when the level of the RF signal for each wave is different for each frequency band, the level of the RF signal for each frequency band can be easily and accurately calculated. .

[Embodiment 3]
Next, a third embodiment of the present invention will be described. This form is a form provided with a plurality of signal lines for transmitting the electric signal output from the photodiode for each frequency band, and connection means for selectively connecting the detection means to the plurality of signal lines. However, unless otherwise specified, the configuration and processing are the same as those of the second embodiment, and the same configurations and processing as those of the second embodiment are denoted by the same reference numerals as those used in the second embodiment. The description is omitted by attaching.

(Constitution)
FIG. 7 is a block diagram of an optical receiver according to the third embodiment. The optical receiver 3 is configured in substantially the same manner as the optical receiver 2 according to the second embodiment, but a branching device 42 provided in each of the first signal line 50 and the second signal line 51. , 43 is connected to a common changeover switch 53, and a difference is that one detector 52 and a reception control unit 60 are sequentially connected to the changeover switch 53 as shown in the figure. The detector 52 is a detector that outputs a detection value corresponding to the signal level of the RF signal branched by the branching units 42 and 43. The reception control unit 60 is a reception control unit that controls each unit of the optical receiver 3, and is configured in the same manner as the reception control unit 50 of the second embodiment except for a configuration that is specifically described. The changeover switch 53 is a connection means for selectively connecting the detector 52 to the plurality of signal lines 50 and 51, and is configured by, for example, a manual switch or an automatic switch (relay or semiconductor component). .

(processing)
Using the optical receiver 3 configured as described above, level adjustment processing is performed in substantially the same manner as in the second embodiment. For example, when a manual switch is used as the changeover switch 53, the user connects the branching device 42 to the detector 52 by changing over the changeover switch 53, and in this state, only the RF signal in the CATV band is described in the second embodiment. Level adjustment processing is performed in the same manner as described above. Thereafter, the user switches the changeover switch 53 to connect the branching device 43 to the detector 52. In this state, only the RF signal in the BS / CS band is subjected to level adjustment processing as in the second embodiment. Alternatively, when an automatic switch is used as the changeover switch 53, the control unit 31 controls the changeover switch 53 to alternately connect the branching device 42 and the branching device 43 to the detector 52, whereby the CATV band and the BS / CS band. In contrast, level adjustment processing is performed alternately as in the second embodiment.

(Effect of Embodiment 3)
As described above, according to the third embodiment, the plurality of signal lines 50 and 51 for transmitting the RF signal for each frequency band and the detector 52 are selectively connected to the plurality of signal lines 50 and 51. Since the changeover switch 53 is provided, the level of the RF signal in the plurality of signal lines 50 and 51 can be detected using the common detector 52, and the detector 52 is provided in each of the plurality of signal lines 50 and 51. Compared to the case, the optical receiver 3 can be configured simply and inexpensively.

[Embodiment 4]
Next, a fourth embodiment of the present invention will be described. In this form, one signal line is used. However, unless otherwise specified, the configuration and processing are the same as those of the first embodiment, and the same configurations and processing as those of the first embodiment are denoted by the same reference numerals as those used in the first embodiment. The description is omitted by attaching.

(Constitution)
FIG. 8 is a block diagram of an optical receiver according to the fourth embodiment. The optical receiver 4 is configured in substantially the same manner as the optical receiver 1 according to the first embodiment, but the first signal line and the second signal line are shared as one signal line. In addition, the separator 13 and the mixer 16 are omitted, and the CA20 band RF signal and the BS / CS band RF signal are gain-adjusted by the GC 20 without being demultiplexed. A branching unit 70 is connected to the preceding stage of the output terminal 18 in one signal line, and a detector 71 and a reception control unit 80 are sequentially connected to the branching unit 70 as illustrated. Here, the amplifier 19 amplifies the CATV signal and the BS / CS signal, the GC 20 adjusts the gain of the CATV signal and the BS / CS signal amplified by the amplifier 19 with a fixed gain, and the amplifier 21 uses the GC 20. The gain-adjusted CATV signal and BS / CS signal are amplified. The branching unit 70 is a branching unit that branches the RF signal amplified by the amplifier 21. The detector 71 is a detector that outputs a detection value corresponding to the signal level of the RF signal branched by the branching unit 70. The reception control unit 80 is a reception control unit that controls each unit of the optical receiver 4, and is configured in the same manner as the reception control unit 30 of the first embodiment except for a configuration specifically described.

(processing)
Using the optical receiver 4 configured in this manner, level adjustment processing is performed in substantially the same manner as in the first embodiment. However, the control unit 31 of the reception control unit 80 does not perform gain control individually in the CATV band and the BS / CS band, and the control unit of the output level of the RF signal is a unit in which the CATV band and the BS / CS band are integrated. Therefore, the wave number and the target output level per wave are also calculated in units of the CATV band and the BS / CS band, and the gain is adjusted collectively by the GC 20.

(Effect of Embodiment 4)
As described above, according to the fourth embodiment, since the RF signal is transmitted through one signal line and the detector 71 is connected to the signal line, the detector 71 is connected to each of the plurality of signal lines. The optical receiver 4 can be configured in a simpler and cheaper manner than when the common detector 71 is switched and connected by the changeover switch 53 to each of the plurality of signal lines.

[Embodiment 5]
Next, a fifth embodiment of the present invention will be described. This form is a form in which the detection means is provided on the downstream side of the automatic gain adjustment means. However, unless otherwise specified, the configuration and processing are the same as those of the fourth embodiment, and the same configurations and processing as those of the fourth embodiment are denoted by the same reference numerals as those used in the fourth embodiment. The description is omitted by attaching.

(Constitution)
FIG. 9 is a block diagram of an optical receiver according to the fifth embodiment. The optical receiver 5 is configured in substantially the same manner as the optical receiver 4 according to the fourth embodiment, but a branching device 90 is disposed between the amplifier 19 and the GC 20, and the branching device 90 detects the signal. The difference is that the device 91 and the reception control unit 100 are sequentially connected as shown in the figure. The branching unit 90 is a branching unit that branches the RF signal amplified by the amplifier. The detector 91 is detection means for outputting a detection value corresponding to the signal level of the RF signal branched by the branching unit 90. The reception control unit 100 is a reception control unit that controls each unit of the optical receiver 5, and is configured in the same manner as the reception control unit 30 of the first embodiment except for a configuration that is specifically described.

(processing)
Using the optical receiver 5 configured as described above, level adjustment processing is performed in substantially the same manner as in the fourth embodiment. However, in this process, the control unit 31 of the reception control unit 100 adjusts the gain of the GC 20 based on the output level of the RF signal detected on the preceding stage of the GC 20, and the result of the gain adjustment of the GC 20 is the RF signal. This is not reflected in the detection of the output level, and so-called feedback control is not performed, so that the level of the RF signal is stabilized. However, here, when outputting the output level of the RF signal per one wave or the output level of the total RF signal, the output by the gain adjustment of the GC 20 with respect to the output level of the RF signal detected by the detector 91. Output after reflecting the level increase / decrease.

(Effect of Embodiment 5)
As described so far, according to the fifth embodiment, since the detector 91 is provided on the upstream side of the GC 20, the gain can be adjusted based on the output level of the RF signal detected on the upstream side of the GC 20, Since the result of gain adjustment is not reflected in the detection of the output level of the RF signal and so-called feedback control is not performed, the level of the RF signal can be stabilized.

[Embodiment 6]
Next, a sixth embodiment of the present invention will be described. In this form, an electrical signal for each frequency is detected and output to the detection means. However, unless otherwise specified, the configuration and processing are the same as those of the first embodiment, and the same configurations and processing as those of the first embodiment are denoted by the same reference numerals as those used in the first embodiment. The description is omitted by attaching.

(Constitution)
FIG. 10 is a block diagram of an optical receiver according to the sixth embodiment. The optical receiver 6 is configured in substantially the same manner as the optical receiver 1 according to the first embodiment, but includes an oscillator 110, a mixer 111, and a BPF (Band Pass) between the branching device 17 and the detector 25. Filter) 112 is connected as shown in the figure. The oscillator 110 is a reference signal output unit that outputs a reference signal having a predetermined frequency. The mixer 111 is a frequency conversion unit that mixes the RF signal branched by the branching unit 17 and the reference signal from the oscillator 110. The BPF 112 is frequency selection means that removes unnecessary portions such as high-frequency components from the signal mixed by the mixer 111 and passes only a signal having a desired frequency. The oscillator 110, the mixer 111, and the BPF 112 function as an electrical signal frequency unit acquisition unit that acquires an RF signal for each frequency and outputs the RF signal to the detector 25.

  The parameter setting table set in the storage unit 32 of the reception control unit 30 is configured in substantially the same manner as the parameter setting table according to the first embodiment, but the alarm upper limit threshold, the alarm lower limit threshold, the target output level, and A target output level automatic adjustment flag is set for each wave. For example, for CATV, if the analog wave is 11 waves and the digital wave is 80 waves, the alarm upper limit threshold, the alarm lower limit threshold, the target output level, and the target output for each of the 11 analog waves The level automatic adjustment flag is set, and the alarm upper limit threshold, the alarm lower limit threshold, the target output level, and the target output level automatic adjustment flag are set for each of the 80 digital waves. The conversion graph according to the sixth embodiment is configured in substantially the same manner as the conversion graph according to the first embodiment, but stores a conversion graph corresponding to each wave (each frequency). .

(processing)
Using the optical receiver 6 configured as described above, level adjustment processing is performed in substantially the same manner as in the first embodiment, but detection and display of the output level of the RF signal is performed for each wave. That is, in the flowchart of FIG. 5, in SA1, the control unit 31 controls the oscillator 110 to change the frequency of the reference signal, and specifies the RF signal transmission frequency, the RF signal modulation method, and the RF signal wave number. . For example, the wave number of the RF signal can be specified by detecting the presence or absence of a signal carrier. Further, the control unit 31 performs the processing from SA2 to SA11 for each wave while changing the frequency of the reference signal by controlling the oscillator 110. For example, in SA4, the output value from the detector averaged in SA3 is converted into the output level of the RF signal using the conversion graph specified in SA2, and in SA5, the output level of the RF signal for each wave Is displayed on the liquid crystal panel of the output unit 34, and in SA6, the output level of the RF signal for each wave is individually displayed on the liquid crystal panel of the output unit 34. Further, in SA7 to SA11, alarm output by comparison with the alarm upper limit threshold and the alarm lower limit threshold is performed individually for each wave.

  Further, in the present embodiment, the target output level can be calculated automatically by the control unit 31. In this case, the “total RF output level optimum value mode”, “upper limit compliance mode”, “ The target output level can be calculated according to the mode selected by the user via the input unit 33 in a predetermined mode such as “lower limit observance mode”, “average value optimum mode”, or “median value optimum mode”. it can.

  The “total RF output level optimum value mode” is a mode in which the total RF output level is set to be optimum. When this mode is selected, the control unit 31 refers to the information set in the storage unit 32, calculates the total value of the target output levels of all the waves, and calculates all the calculated total values. As a target output level with respect to the total output level of the waves, gain adjustment by the GCs 20 and 23 is performed. For example, as shown in the parameter setting table of FIG. 3, when a target output level is set for each transmission frequency band, a total value of the target output levels for each transmission frequency band is calculated, and the calculated total The gain is adjusted by the GCs 20 and 23 with the value as the target output level for the total output level of all waves.

  The “upper limit compliance mode” is a mode in which all waves are set not to exceed the upper limit. When this mode is selected, the control unit 31 refers to the information set in the storage unit 32, calculates the alarm upper limit threshold for each wave, and does not exceed the calculated alarm upper limit threshold. The gain is adjusted by the GCs 20 and 23. The target output level in this case is set to a level obtained by subtracting a predetermined value or a predetermined ratio from the calculated alarm upper limit threshold. For example, as shown in the parameter setting table of FIG. 3, when an alarm upper limit threshold is set with respect to the total output level of the RF signal, the alarm upper limit threshold is divided by the wave number, so that An alarm upper threshold can be calculated.

  “Lower limit observance mode” is a mode in which all waves are set not to be lower than the lower limit. When this mode is selected, the control unit 31 refers to the information set in the storage unit 32, calculates the alarm lower limit threshold for each wave, and does not fall below the calculated alarm lower limit threshold. The gain is adjusted by the GCs 20 and 23. The target output level in this case is set to a level obtained by adding a predetermined value or a predetermined ratio to the calculated alarm lower limit threshold. For example, as shown in the parameter setting table of FIG. 3, when the alarm lower limit threshold is set for the total output level of the RF signal, the alarm lower limit threshold is divided by the wave number to obtain the An alarm lower threshold value can be calculated.

  The “average value optimum mode” is a mode in which an RF output level average value obtained by dividing the total RF output level by the wave number is set to an optimum value for one wave. When this mode is selected, the control unit 31 refers to the information set in the storage unit 32, calculates the average value for each wave of the target output level, and calculates the calculated average value for each wave. As a target output level with respect to the output level, gain adjustment by the GCs 20 and 23 is performed. For example, as shown in the parameter setting table of FIG. 3, when a target output level is set for each transmission frequency band, the average value is obtained by dividing the target output level for each transmission frequency band by the wave number. Calculate.

  The “median optimum mode” is a mode in which the median of RF output levels obtained by statistically calculating all RF output levels is set to an optimum value. When this mode is selected, the control unit 31 arranges the RF output levels for each wave in descending order and sets the value at the center of the whole as a median value, or when the wave number is an even number, The average of the two values is the median value. Then, the median value is used as a target output level for the output level of each wave, and gain adjustment by the GCs 20 and 23 is performed.

  In the case of the “lower limit observance mode”, “average value optimum mode”, and “median value optimum mode” described so far, a problem may occur when a certain signal is OFF or extremely small. That is, in the “lower limit compliance mode”, if the RF output level is too small, the gain becomes extremely large. Further, in the “average value optimum” mode, if the RF output level is too small, the gain is also increased, although it is slightly improved from the “lower limit value observance mode”. In addition, it is thought that there is no effect in the “median optimum mode”, but if there are many wave numbers that are OFF, the median value itself may be at the OFF level, so the gain is still Too big. Therefore, the ON / OFF determination threshold value of the RF output level in these modes is set in advance, and when the control unit 31 selects these modes and the RF output level falls below the determination threshold value, The value is excluded from the sample, and the number of samples (= wave number) is reduced by the number of the excluded value, and the above calculation is performed based on the remaining sample not excluded and the reduced sample number. You may go.

(Effect of Embodiment 6)
As described above, according to the sixth embodiment, since the electric signal frequency unit acquisition means for acquiring the RF signal for each frequency and outputting it to the detector 25 is provided, the detection of the level of the RF signal is performed for each frequency. Therefore, it is possible to easily and accurately detect the level of the RF signal for each wave.

[Embodiment 7]
Next, a seventh embodiment of the present invention will be described. This form is a form which compensates the f characteristic of a detector using a compensation means. However, unless otherwise specified, the configuration and processing are the same as those of the first embodiment, and the same configurations and processing as those of the first embodiment are denoted by the same reference numerals as those used in the first embodiment. The description is omitted by attaching.

(Constitution)
FIG. 11 is a block diagram of an optical receiver according to the seventh embodiment. The optical receiver 7 is configured in substantially the same manner as the optical receiver 1 according to the first embodiment, but is configured by connecting a TILT circuit 120 between the branching device 17 and the detector 25. . The TILT circuit 120 is compensation means for compensating the f characteristic of the detector 25, and is set so that the level of the RF signal becomes substantially flat over a wide band. For example, the TILT circuit 120 is set to increase the level of the RF signal as the frequency of the RF signal becomes higher due to the characteristic almost opposite to the f characteristic of the detector 25. In the present embodiment, as the conversion graph stored in the storage unit 32, a common conversion graph is set regardless of the transmission frequency that can be taken by the RF signal.

(processing)
Using the optical receiver 7 configured as described above, level adjustment processing is performed in substantially the same manner as in the first embodiment, but the conversion from the output value of the detector 25 to the output level of the RF signal is performed by the storage unit 32. This is done using a common conversion graph stored in. That is, since the RF signal branched by the branching unit 17 is level-compensated by the TILT circuit 120 and then input to the detector 25, the control unit 31 of the reception control unit 30 performs the SA2 operation in the flowchart of FIG. The processing is omitted, and in SA4, the output value of the detector 25 is converted into the output level of the RF signal using the common conversion graph stored in the storage unit 32.

(Effect of Embodiment 7)
As described above, according to the seventh embodiment, since the TILT circuit 120 for compensating the frequency characteristic of the detector 25 is provided, the level of the RF signal can be flat over a wide band, and the detection can be performed. Since it is not necessary to hold a plurality of pieces of conversion information according to the frequency characteristics of the device 25, the level of the RF signal can be detected easily and accurately without using a plurality of pieces of conversion information.

[Modification]
Although the embodiments of the present invention have been described above, the specific configuration and means of the present invention may be arbitrarily modified and improved within the scope of the technical idea of each invention described in the claims. Can do. Hereinafter, some of such modifications will be described.

(About problems to be solved and effects of the invention)
First, the problems to be solved by the invention and the effects of the invention are not limited to the above-described contents, and the present invention solves the problems not described above or has the effects not described above. There are also cases where only some of the described problems are solved or only some of the described effects are achieved.

(About mutual application of each embodiment and each modification)
A part of each embodiment or each modification may be exchanged. For example, in the seventh embodiment, the TILT circuit 120 is provided in the previous stage of the detector 25. Similarly, the TILT circuit 120 can be provided in the previous stage of each detector 44 in the second embodiment.

(About control of electric signal level)
Comparison with the alarm upper limit threshold value or alarm lower limit threshold value based on the level of the RF signal calculated based on the detection values detected by the detectors 25, 44, 45, 52, 71, 91, and control based on the target output level As long as it is possible on the circuit configuration, any one of each wave or a plurality of waves may be used. For example, in the first embodiment, the alarm upper limit threshold and the alarm lower limit threshold for the total output level of a plurality of waves are set. However, the alarm upper limit threshold for each wave and the alarm lower limit threshold for each wave are set, and these 1 The necessity of alarm may be determined by comparing the alarm upper limit threshold for each wave and the alarm lower limit threshold for each wave with the RF signal level calculated for each wave as described above. . In the first embodiment, the target output level is set for each transmission frequency band. However, when the circuit configuration is such that the total output level of a plurality of waves can be controlled, the target output for the total output level of the plurality of waves is set. A level may be set, and the total output level of a plurality of waves may be controlled based on this target output level. Alternatively, when the circuit configuration is such that the output level for each wave can be controlled, a target output level for each wave is set, and the target output level for each wave is controlled based on this target output level. Also good.

(Specification of transmission frequency band, modulation method, and wave number of electrical signals)
In each of the above embodiments, the transmission frequency band, modulation method, and wave number of the RF signal are specified by referring to information stored in the storage unit 32. In addition to this, the RF signal is publicly known. It can be specified by other methods such as specifying by analyzing by the above method.

(About conversion information)
In each of the above embodiments, the level of the RF signal is calculated using the conversion graph stored in the storage unit 32, but a conversion formula or a conversion table may be used instead of the conversion graph. The conversion formula is a calculation formula for converting the level of the output value from the detectors 25, 44, 45, 52, 71, 91 into the level of the RF signal, and the conversion table is the detectors 25, 44, 45, 5 is a table in which the output values of 52, 71, 91 and the level of the RF signal are set to correspond to each other. For example, as in the case of the conversion graph, a plurality of these conversion formulas and conversion tables are set in the storage unit 32 according to each modulation method and each transmission frequency band, and one is set based on each modulation method and each transmission frequency band. Two conversion formulas and conversion tables can be selected, and the output values of the detectors 25, 44, 45, 52, 71 and 91 can be converted into RF signal levels using the selected conversion formulas and conversion tables.

These conversion graphs, conversion formulas, or conversion tables are also useful in the following cases. That is, when an analog broadcast wave in the VFH band is mainly operated, conversion is performed using a conversion graph, a conversion equation, or a conversion table set according to any frequency in the VFH band, When the broadcast wave is stopped, the RF signal level detection accuracy is improved by switching to a conversion graph, conversion formula, or conversion table set according to the frequency of the UHF band. be able to. Such switching may be manually performed by the user via the input unit 33, or automatically performed by the control unit specifying the frequency band and the modulation method as in the first embodiment. May be.
(Appendix)
The optical receiver according to appendix 1 is an optical receiver that receives an optical signal and converts the optical signal into an electrical signal, a photodiode for converting the optical signal into the electrical signal, and after being output by the photodiode Detecting means for outputting a detection value corresponding to the level of the electric signal in any state until it is output to the outside of the optical receiver, and calculating the level of the electric signal based on the detection value of the detecting means. And control means for performing predetermined control for enabling adjustment of the level of the electric signal output to the outside of the optical receiver based on the calculated level of the electric signal.
The optical receiver according to appendix 2 is the optical receiver according to appendix 1, wherein the optical signal includes a plurality of wave signals, and includes wave number storage means for storing the wave numbers of the plurality of waves. Then, based on the level of the electric signal calculated based on the detection value of the detection means and the wave number stored in the wave number storage means, the level of the electric signal for each wave is calculated, and the calculated 1 Based on the level of the electric signal for each wave, predetermined control is performed so that the level of the electric signal for each wave can be adjusted.
The optical receiver of appendix 3 is the optical receiver of appendix 2, wherein the wave number storage means stores the wave numbers of the plurality of waves for each band and modulation scheme of the optical signal, and the control means Based on the level of the electric signal calculated based on the detection value of the detection means, and the wave number for each band and the modulation method stored in the wave number storage means, the one wave for each band and the modulation method The level of each electric signal is calculated.
The optical receiver according to appendix 4 is the optical receiver according to any one of appendices 1 to 3, wherein conversion information for converting a detection value of the detection means into a level of an electric signal is converted to a frequency of the detection means. Conversion information storage means for storing for each band having different characteristics, wherein the detection means is a detection value according to the level of the electrical signal, and outputs a detection value according to the frequency characteristic of the detection means, The control means acquires the conversion information of the band corresponding to the frequency of the electrical signal from the conversion information stored in the conversion information storage means, and the detection value of the detection means based on the acquired conversion information The level of the electric signal is calculated by converting and the predetermined control is performed based on the calculated level of the electric signal.
The optical receiver according to appendix 5 is the optical receiver according to appendix 4, in which the conversion information storage means stores the conversion information for each modulation method of the optical signal, and the detection means A detection value corresponding to the level, and a detection value corresponding to the modulation method of the optical signal, and the control means modulates the optical signal from the conversion information stored in the conversion information storage means Obtaining the conversion information corresponding to the method, calculating the level of the electrical signal by converting the detection value of the detection means based on the acquired conversion information, based on the calculated level of the electrical signal, The predetermined control is performed.
The optical receiver according to appendix 6 is the optical receiver according to any one of appendices 1 to 5, wherein the control unit performs an averaging process on a detection value of the detecting unit, and the detection process after the averaging process is performed. The level of the electric signal is calculated based on the value.
The optical receiver according to appendix 7 is the optical receiver according to appendix 1, and includes a plurality of signal lines for transmitting the electrical signal output from the photodiode for each frequency band, and the detection means is provided for each signal line. It is provided.
The optical receiver according to appendix 8 is the optical receiver according to appendix 1, wherein a plurality of signal lines for transmitting electrical signals output from the photodiodes by frequency band, and the detection means are connected to the plurality of signal lines. And a connection means for selectively connecting to.
The optical receiver according to supplementary note 9 is the optical receiver according to any one of supplementary notes 1 to 8 in any state from the output from the photodiode to the output to the outside of the optical receiver. Manual gain adjusting means for manually adjusting the gain of the electric signal is provided.
The optical receiver according to appendix 10, in the optical receiver according to any one of appendices 1 to 9, is output by the photodiode based on the level of the electrical signal calculated by the control means. An automatic gain adjusting means for adjusting the gain of the electric signal in any state until it is output to the outside of the optical receiver is provided.
The optical receiver according to appendix 11 is the optical receiver according to appendix 10, in which the detection means is provided on the upstream side of the automatic gain adjustment means.
The optical receiver according to supplementary note 12 is the optical receiver according to any one of supplementary notes 1 to 11, in any state from the output from the photodiode to the output to the outside of the optical receiver. An electric signal frequency unit acquisition means for acquiring an electric signal for each frequency from the electric signal and outputting the electric signal to the detection means is provided.
The optical receiver according to appendix 13 is the optical receiver according to any one of appendices 1 to 3, comprising compensation means for compensating the frequency characteristic of the detection means.
The optical receiver according to appendix 14 is the optical receiver according to any one of appendices 1 to 13, further comprising display means for displaying the level of the electric signal calculated by the control means.
(Additional effects)
According to the optical receiver of appendix 1, the level of the electrical signal is calculated based on the detection value of the detection means, and the level of the electrical signal output to the outside of the optical receiver based on the level of the electrical signal Since the predetermined control is performed to make the adjustment possible, the level of the electric signal can be easily and accurately adjusted.
According to the optical receiver described in Supplementary Note 2, since predetermined control for enabling adjustment of the level of the electric signal for each wave is performed, gain optimization corresponding to the wave number is performed even in multi-wave operation. Can be achieved easily and accurately.
According to the optical receiver described in appendix 3, since the level of the electric signal for each wave is calculated based on the level of the electric signal, the band, and the wave number for each modulation method, 1 for each band and modulation method. Even when the level of the electric signal for each wave is different, the level of the electric signal for each band and modulation method can be calculated easily and accurately.
According to the optical receiver described in appendix 4, since the level of the electric signal is calculated by converting the detection value of the detection unit based on the conversion information corresponding to the frequency of the electric signal, the frequency characteristic of the detection unit is used. Even when the level of the detected value varies, the level of the electric signal can be easily and accurately calculated.
According to the optical receiver of appendix 5, the level of the electric signal is calculated by converting the detection value of the detection means based on the conversion information corresponding to the modulation method of the optical signal. Even if the level of the detected value fluctuates due to this, the level of the electric signal can be calculated easily and accurately.
According to the optical receiver described in appendix 6, since predetermined control is performed based on the result of the averaging process on the detection value of the detection means, the level of the detection value of the detection means varies due to fluctuations in the amplitude of the electrical signal. Even so, it is possible to easily and accurately calculate the level of the electric signal.
According to the optical receiver described in appendix 7, since the detection means is provided for each signal line for transmitting the electric signal for each frequency band, level detection can be performed for each frequency band, and for each wave for each frequency band. Even when the levels of the electrical signals are different, the level of the electrical signal for each frequency band can be calculated easily and accurately.
Since the optical receiver according to appendix 8 includes the plurality of signal lines for transmitting the electrical signal for each frequency band and the connection means for selectively connecting the detection means to the plurality of signal lines, The level of the electric signal in the plurality of signal lines can be detected using the detection means, and the optical receiver can be configured simply and inexpensively as compared with the case where the detection means is provided in each of the plurality of signal lines. .
According to the optical receiver described in appendix 9, since the manual gain adjusting means for manually adjusting the level of the electric signal is provided, the level of the electric signal can be manually adjusted to the optimum value.
According to the optical receiver described in appendix 10, since the automatic gain adjusting means for adjusting the gain of the electric signal is provided, the level of the electric signal can be automatically adjusted to the optimum value.
According to the optical receiver described in appendix 11, since the detection unit is provided on the upstream side of the automatic gain adjustment unit, the gain is adjusted based on the output level of the electrical signal detected on the upstream side of the automatic gain adjustment unit. Since the gain adjustment result is not reflected in the detection of the output level of the electric signal, and so-called feedback control is not performed, the level of the electric signal can be stabilized.
According to the optical receiver described in appendix 12, since the electric signal frequency unit acquisition unit that acquires the electric signal for each frequency and outputs the electric signal to the detection unit is provided, the level of the electric signal is detected for each frequency. Therefore, the level of the electric signal for each wave can be detected easily and accurately.
According to the optical receiver described in appendix 13, since the compensation unit for compensating the frequency characteristic of the detection unit is provided, the level of the electric signal can be flat over a wide band, and the frequency characteristic of the detection unit can be obtained. Accordingly, since it is not necessary to hold a plurality of pieces of conversion information, the level of the electric signal can be easily and accurately detected without using a plurality of pieces of conversion information.
According to the optical receiver described in appendix 14, since the display unit that displays the level of the electric signal calculated by the control unit is provided, the user can easily check the level of the electric signal through the display unit. Is possible.

1-7 Optical receiver 10 PD
11, 19, 21, 22, 24 Amplifier 12 AGC circuit 13 Separator 14, 40, 50 First signal line 15, 41, 51 Second signal line 16, 111 Mixer 17, 42, 43, 70, 90 Branching device 18 Output terminal 20, 23 GC
25, 44, 45, 52, 71, 91 Detector 30, 50, 60, 80, 100 Reception control unit 31 Control unit 32 Storage unit 33 Input unit 34 Output unit 53 Changeover switch 110 Oscillator 112 BPF
120 TILT circuit

Claims (13)

An optical receiver that receives an optical signal and converts it into an electrical signal,
The optical signal is an optical signal carrying a plurality of electrical signals,
A photodiode for converting the optical signal into the electrical signal;
Detection means for outputting a detection value corresponding to the level of the electrical signal in any state from the output by the photodiode to the output to the outside of the optical receiver;
The level of the electric signal is calculated based on the detection value of the detection means, and the level of the electric signal output to the outside of the optical receiver can be adjusted based on the calculated level of the electric signal. Control means for performing predetermined control;
Wave number storage means for storing the wave numbers of the plurality of waves,
The control means calculates the level of the electric signal for each wave based on the level of the electric signal calculated based on the detection value of the detection means and the wave number stored in the wave number storage means, Based on the calculated electric signal level for each wave, a predetermined control is performed to make the electric signal level for each wave adjustable.
Optical receiver. The wave number storage means stores the wave numbers of the plurality of waves for each band and modulation method of the electric signal,
The control means includes the band and the modulation based on the level of the electric signal calculated based on the detection value of the detection means and the band and the wave number for each modulation method stored in the wave number storage means. The level of the electric signal for each wave in each method is calculated.
The optical receiver according to claim 1. Conversion information storage means for storing conversion information for converting a detection value of the detection means into a level of an electric signal for each band having different frequency characteristics of the detection means,
The detection means is a detection value according to the level of the electrical signal, and outputs a detection value according to the frequency characteristic of the detection means,
The control means acquires the conversion information of the band corresponding to the frequency of the electrical signal from the conversion information stored in the conversion information storage means, and detects the detection means based on the acquired conversion information. The level of the electric signal is calculated by converting a value, and the predetermined control is performed based on the calculated level of the electric signal.
The optical receiver according to claim 1 or 2. The conversion information storage means stores the conversion information for each modulation method of the electric signal,
The detection means is a detection value according to the level of the electric signal, and outputs a detection value according to the modulation method of the electric signal,
The control means acquires the conversion information corresponding to the modulation method of the electrical signal from the conversion information stored in the conversion information storage means, and the detection value of the detection means based on the acquired conversion information To calculate the level of the electric signal, and based on the calculated level of the electric signal, to perform the predetermined control,
The optical receiver according to claim 3 . The control means performs an averaging process on the detection value of the detection means, and calculates the level of the electric signal based on the averaged detection value.
The optical receiver as described in any one of Claim 1 to 4 . The electric signal output from the photodiode, comprising a plurality of signal lines for transmitting by frequency band,
The detection means is provided for each signal line,
The optical receiver according to claim 1 . An optical receiver that receives an optical signal and converts it into an electrical signal,
A photodiode for converting the optical signal into the electrical signal;
Detection means for outputting a detection value corresponding to the level of the electrical signal in any state from the output by the photodiode to the output to the outside of the optical receiver;
The level of the electric signal is calculated based on the detection value of the detection means, and the level of the electric signal output to the outside of the optical receiver can be adjusted based on the calculated level of the electric signal. Control means for performing predetermined control;
A plurality of signal lines for transmitting electrical signals output from the photodiodes by frequency band ;
Connection means for selectively connecting the detection means to the plurality of signal lines;
An optical receiver. Manual gain adjusting means for manually adjusting the gain of the electrical signal in any state from the output by the photodiode to the output to the outside of the optical receiver;
An optical receiver according to any one of claims 1 to 7 . Based on the level of estimated electrical signal by said control means, for adjust the gain of the electrical signal in one of two states from the output by the photodiode until the output to the outside of the optical receiver Automatic gain adjustment means,
An optical receiver according to any one of claims 1 to 8. The detection means is provided on the upstream side of the automatic gain adjustment means.
The optical receiver according to claim 9 . An electrical signal frequency unit for obtaining an electrical signal for each frequency from an electrical signal in any state from being output by the photodiode to being output to the outside of the optical receiver, and outputting the electrical signal to the detection means With acquisition means,
The optical receiver as described in any one of Claim 1 to 10 . Compensating means for compensating the frequency characteristics of the detecting means ,
The optical receiver according to claim 1 or 2 . Comprising display means for displaying the level of the electrical signal calculated by the control means ;
The optical receiver according to any one of claims 1 to 12 .

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