JP4405410B2 - Receiver - Google Patents

Description

  The present invention relates to a receiving apparatus used for a relay transmitter that relays a terrestrial digital broadcast signal from a master station, for example.

  In the terrestrial broadcasting system, a relay station is installed for the purpose of expanding the broadcasting service area and eliminating difficult viewing areas. In the relay station, a signal directly receiving a broadcast wave or a broadcast signal received on a dedicated line such as TTL (Transmitter to Transmitter Link) is input to the transmitter again and transmitted.

  By the way, in the relay station, due to the occurrence of up fading or attenuating fading, the quality of the received signal may be deteriorated so that it cannot be used for broadcasting.

The current analog broadcasting relay station monitors the received signal level of the transmission system in use, and if the level exceeds the reference value due to the occurrence of up-fading, it switches to a transmission system with an attenuator. (For example, Patent Document 1). In this case, there is no trouble that causes a serious problem in actual broadcasting.
JP 2000-315960 A.

  By the way, in Japanese terrestrial broadcasting, the transition from current analog broadcasting to digital broadcasting by OFDM (Orthogonal Frequency Division Multiplexing) modulation method has been decided, and various developments are being promoted for the realization. Here, in digital broadcasting, it is desired to improve the following problems.

  First, since the frequency characteristic in the band of the OFDM signal is flat, even if the signal is not received, the noise component may rise in the receiving circuit and appear as an OFDM signal. For this reason, it is difficult to monitor signal quality degradation at the level of the received signal, and quality monitoring technology for switching relay broadcast waves in analog broadcasting cannot be used.

  Therefore, an object of the present invention is to provide a receiving apparatus that can maintain the signal quality of a received signal satisfactorily when used in a broadcast wave relay station.

In order to achieve the above object, the present invention is configured as follows.
A receiving means for receiving an arbitrary signal from an incoming radio wave and outputting the received signal at an arbitrary loss level, a monitoring means for monitoring the reception quality of the signal output by the receiving means, and a monitoring result of the monitoring means And a control means for controlling the loss level of the receiving means. The receiving means includes a receiving antenna for receiving an arbitrary signal and a radome covering at least a part of the receiving antenna, and the control means controls the radome based on the monitoring result of the monitoring means. To change the free space loss. Furthermore, the monitoring means has first detection means for detecting the output signal level of the reception means, and second detection means for detecting the carrier-to-noise power ratio of the reception signal from the output of the reception means, and the control means Is characterized in that the loss level of the receiving means is controlled based on the detection results of the first and second detecting means.

  According to this configuration, in addition to the signal level of the reception signal obtained at the reception antenna via the radome, the carrier-to-noise power ratio of the reception signal is detected, and based on these detection results, up-fading or attenuating fading is performed. The radome is controlled so that there is no effect, and the free space loss is changed.

  Therefore, even when the signal is not received, it is possible to prevent erroneous detection of the signal due to noise in the system, thereby reliably detecting the quality deterioration of the received signal due to up fading or attenuating fading. It is possible to maintain good signal quality. In addition, when the quality of the received signal is deteriorated due to up-fading or attenuating fading, the radome is controlled to prevent the quality deterioration. Therefore, the circuit configuration can be easily reduced in size.

  A receiving means for receiving an arbitrary signal from an incoming radio wave, a distributing means for distributing the received signals obtained by the receiving means to two systems having different signal levels to process each other, and one of the two systems of signals Switching means for selectively deriving a signal as a transmission signal, monitoring means for monitoring the reception quality of each of the two signals, and control means for switching control of the switching means based on the monitoring result of the monitoring means It is what I did. One of the two systems is provided with an attenuator for attenuating the signal distributed by the distributing means by a predetermined level, and the monitoring means monitors the reception quality of the output signal of the attenuator. . Furthermore, the monitoring means has a first detection means for detecting the signal levels of the two systems, and a second detection means for detecting the carrier-to-noise power ratio of the received signal from the signals of the two systems, respectively. The means is characterized by switching control of the switching means based on the detection results of the first and second detection means.

  According to this configuration, in addition to the signal level of the received signal, the carrier-to-noise power ratio of the received signal is detected, and system switching is performed based on these detection results so as to eliminate the influence of up-fading or attenuating fading. .

  Therefore, even when no signal is received, it is possible to prevent erroneous detection of the signal due to noise in the system, etc., thereby reliably detecting the quality deterioration of the received signal due to up fading or attenuating fading and switching output It is possible to maintain good signal quality.

  As described above in detail, according to the present invention, when used in a broadcast wave relay station, it is possible to provide a receiving apparatus capable of maintaining a good signal quality of a received signal.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
(First embodiment)
FIG. 1 is a block diagram showing a configuration of a receiving apparatus according to the first embodiment of the present invention. This receiving apparatus is used for a broadcast wave relay station.

  In FIG. 1, reference numeral 11 denotes a receiving unit, which includes, for example, a receiving antenna 111 for receiving a digital broadcast signal in the OFDM scheme received via TTL, and a radome 112 that covers the receiving antenna 111. The radome 112 is made of a material having radio wave permeability.

  A digital broadcast signal received by the receiving unit 11, that is, an RF (Radio Frequency) input signal is subjected to signal processing such as frequency conversion from the RF band to the IF band by the signal processing unit 12, and then transmitted to a transmitter (not shown). Sent out.

  On the other hand, the signal input to the signal processing unit 12 is supplied to a reception input level monitoring unit 13 and a C / N (Carrier / Noise) monitoring unit 14. The reception input level monitoring unit 13 monitors the signal level of the input signal, and the monitoring result is supplied to the control unit 15. The C / N monitoring unit 14 monitors the C / N ratio of the input signal and evaluates the degree of deterioration. The evaluation value is supplied to the control unit 15.

  Based on the monitoring result from the reception input level monitoring unit 13 and the evaluation value from the C / N monitoring unit 14, the control unit 15 determines quality degradation due to up-fading or attenuating fading so that the signal quality is improved. The radome 112 is controlled to change the free space loss.

Next, the operation in the above configuration will be described.
Previously, as shown in FIG. 2, the digital broadcast signal received by the receiving antenna 1 is processed by the receiver 2 and input to the transmitter again to be transmitted. However, when up fading occurs, as shown in FIG. 3, the reception input level to the receiver 2 becomes high, so that the receiver 2 is saturated and C / N deteriorates, and in the field of the broadcast area. An error will occur.

  Therefore, in the first embodiment, the broadcast signal supplied to the signal processing unit 12 is supplied to the reception input level monitoring unit 13 and the C / N monitoring unit 14 respectively, and the reception input level monitoring unit 13 sets the reception signal level. Then, the C / N monitoring unit 14 detects the C / N ratio of the broadcast signal, and outputs the detection result to the control unit 15 as an evaluation value of the signal quality.

  In the signal quality monitoring method used in the C / N monitoring unit 14, the amount of noise that can obtain a certain error rate in the digital broadcast signal is determined by looking at the C / N ratio of the digital broadcast signal, and the ratio From this, the degree of deterioration is detected.

FIG. 4 is a flowchart showing a specific processing procedure of the control unit 15.
First, the control unit 15 takes in the monitoring result from the reception input level monitoring unit 13, and determines whether or not the reception level of the digital broadcast signal that is the monitoring result exceeds the reference value (step ST4a). Here, when the reception level exceeds the reference value (Yes), the control unit 15 takes in the quality evaluation value from the C / N monitoring unit 14 and determines whether the quality evaluation value is less than the reference evaluation value. (Step ST4b).

  Here, if the quality evaluation value is equal to or higher than the reference evaluation value (No), the control unit 15 determines that the influence of noise or the like in the signal processing unit 12 generated when the signal is not received and determines the above step ST4a. Move on to processing.

  On the other hand, when the quality evaluation value is lower than the reference evaluation value (Yes), the control unit 15 determines that the influence is due to up-fading and controls the radome 112 so that the quality of the digital broadcast signal is improved (step ST4c). . Thereafter, the processing from step ST4a to step ST4c is repeatedly executed.

  In addition, although the said process was demonstrated as an anti-fading countermeasure, it can respond also to attenuating fading. In this case, the control unit 15 determines whether or not the reception level is lower than the reference value in step ST4a, and determines whether or not the quality evaluation value is lower than the reference evaluation value in step ST4b.

  As described above, in the first embodiment, the signal level of the digital broadcast signal received by the reception antenna 111 via the radome 112 is detected by the reception input level monitoring unit 13 and the C / N ratio of the digital broadcast signal is detected. Is detected by the C / N monitoring unit 14, and the control unit 15 controls the radome 112 so as to eliminate the influence of up-fading or attenuating fading based on the detection results, thereby changing the free space loss.

  Therefore, it is possible to prevent the signal processing unit 12 from being saturated due to up-fading or attenuating fading and deteriorating the C / N ratio, thereby maintaining a good signal quality of the received signal and improving the ground level. A digital broadcast transmission network can be constructed.

  Further, even when no signal is received, it is possible to prevent a signal due to noise or the like in the signal processing unit 12 from being erroneously detected and taking measures for up fading or attenuation fading.

  In addition, when the quality of the received signal is deteriorated due to up-fading or attenuating fading, the radome 112 is controlled to prevent the quality deterioration. Therefore, the circuit configuration can be easily downsized.

(Second Embodiment)
FIG. 5 is a block diagram showing a configuration of a receiving apparatus according to the second embodiment of the present invention.

  In FIG. 5, a digital broadcast signal received by the receiving antenna 21 is distributed into two systems by a distributor 22, one of which is attenuated by a predetermined level by an attenuator 23 and supplied to a signal processing unit 24, and the other is a signal processing unit 25. To be supplied. Here, the system including the attenuator 23 and the signal processing unit 24 is defined as 1 system, and the system including the signal processing unit 25 is defined as 2 systems.

  The 1-system input digital broadcast signal is supplied to the switch 26 after predetermined signal processing is applied by the signal processing unit 24. Similarly, the 2-system input digital broadcast signal is supplied to the switch 26 after predetermined signal processing is applied by the signal processing unit 25. The switch 26 selectively derives one of the first and second systems.

  On the other hand, the digital broadcast signals respectively input to the signal processing units 24 and 25 are supplied to the reception input level monitoring unit 27 and the C / N monitoring unit 28. The reception input level monitoring unit 27 monitors the signal level of the input signal, and the monitoring result is supplied to the control unit 29. The C / N monitoring unit 28 monitors the C / N ratio of the input signal and evaluates the degree of deterioration. The evaluation value is supplied to the control unit 29.

  Based on the monitoring result from the reception input level monitoring unit 27 and the evaluation value from the C / N monitoring unit 28, the control unit 29 determines quality degradation due to up fading or attenuating fading so that the signal quality is improved. The switch 26 is controlled to be switched.

Next, the operation in the above configuration will be described.
In the second embodiment, the digital broadcast signals supplied to the signal processing units 24 and 25 are supplied to the reception input level monitoring unit 27 and the C / N monitoring unit 28, respectively, and the reception input level monitoring unit 27 receives the reception signal level. The C / N monitoring unit 28 detects the C / N ratio of the digital broadcast signal, and outputs the detection result to the control unit 29 as an evaluation value of the signal quality.

  In the signal quality monitoring method used in the C / N monitoring unit 28, the amount of noise that can obtain a certain error rate in the digital broadcast signal is determined by looking at the C / N ratio of the digital broadcast signal, and the ratio From this, the degree of deterioration is detected.

  FIG. 6 is a flowchart showing a specific processing procedure of the control unit 29. Here, it is assumed that system 2 is selected in the initial state.

  First, the control unit 29 takes in the monitoring result from the reception input level monitoring unit 27, and determines whether or not the reception level of the 2-system digital broadcast signal as the monitoring result exceeds the reference value (step ST6a). Here, when the reception level exceeds the reference value (Yes), the control unit 29 takes in the two system quality evaluation values from the C / N monitoring unit 28, and the two system quality evaluation values are less than the reference evaluation value. It is determined whether or not there is (step ST6b).

  Here, if the quality evaluation value of the second system is equal to or higher than the reference evaluation value (No), the control unit 29 determines that it is an influence of noise or the like in the signal processing unit 25 generated when the signal is not received. The process proceeds to step ST6a.

  On the other hand, when the quality evaluation value of the second system is lower than the reference evaluation value (Yes), the control unit 29 determines that the influence is caused by the up-fading, and controls the switch 26 to select the first system (step). ST6c).

  Next, the control unit 29 determines whether or not the reception level of the 1-system digital broadcast signal is lower than the reference value (step ST6d). Here, when the reception level of the first system falls below the reference value (Yes), the control unit 29 takes in the first system quality evaluation value from the C / N monitoring unit 28, and the first system quality evaluation value becomes the reference evaluation. It is determined whether it is less than the value (step ST6e).

  Here, if the quality evaluation value of the first system is equal to or higher than the reference evaluation value (No), the control unit 29 determines that the influence of noise or the like in the signal processing unit 24 generated when the signal is not received. The process proceeds to step ST6d.

  On the other hand, when the quality evaluation value of the first system is lower than the reference evaluation value (Yes), the control unit 29 determines that the influence is due to attenuating fading and controls the switch 26 to select the second system ( Step ST6f). Thereafter, the processing from step ST6a to step ST6f is repeatedly executed. In normal times, systems 1 and 2 are used for active / preliminary switching.

  As described above, in the second embodiment, the digital broadcast signal received by the reception antenna 21 is distributed into two systems by the distributor 22, and one signal is attenuated by a predetermined level by the attenuator 23 to the signal processing unit 24. The other signal is directly input to the signal processing unit 25, the signal level of the digital broadcast signal input to the signal processing units 24, 25 is detected by the reception input level monitoring unit 27, and the signal processing units 24, 25 are detected. When the C / N ratio of the digital broadcast signal input to the C / N monitoring unit 28 is detected by the C / N monitoring unit 28 and the quality evaluation value of the system in the transmission state falls below the reference value based on the detection result, the control unit 29 increases. It is determined that the influence is caused by fading or attenuating fading, and the system of the switch 26 is switched.

Therefore, the same effect as that of the first embodiment can be obtained, and thereby, it is possible to reliably detect the quality deterioration of the received signal due to up-fading or attenuating fading and maintain the signal quality of the switching output well. .
(Other embodiments)
The present invention is not limited to the above embodiments. For example, in the first embodiment, an example has been described in which deterioration of the C / N ratio due to up-fading or attenuating fading is prevented by controlling the radome. However, the present invention is not limited to this, and other shields may be used, for example. Any loss level can be controlled as long as it can be controlled.

  Further, in each of the above embodiments, the example in which the reception level and the reception C / N ratio are monitored has been described. However, in addition to the reception level and the reception C / N ratio, those that can monitor the reception quality of the reception signal may be used. . For example, the digital signal may be demodulated to detect error rates before and after error correction.

  Furthermore, each of the above embodiments is applied to a broadcast wave relay station. However, the present invention is not limited to this, and can be applied to other digital communication systems that need to take up fading countermeasures or attenuating fading countermeasures. Of course.

  In addition, the configuration of the receiving apparatus, the type of signal to be handled, the reception quality monitoring method, the loss level control procedure, the system switching procedure, and the like can be implemented with various modifications without departing from the gist of the present invention.

The block diagram which shows the structure of the receiver concerning 1st Embodiment of this invention. The block diagram which shows the structure of the broadcast wave relay station used before. The signal characteristic figure at the time of being influenced by up fading. The flowchart which shows the control processing procedure of the control part in the said 1st Embodiment. The block diagram which shows the structure of the receiver concerning 2nd Embodiment of this invention. The flowchart which shows the control processing procedure of the control part in the 2nd Embodiment.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 11 ... Reception part, 12, 24, 25 ... Signal processing part, 13, 27 ... Reception input level monitoring part, 14, 28 ... C / N monitoring part, 15, 29 ... Control part, 21, 111 ... Reception antenna, 22 ... Distributor, 23 ... Attenuator, 26 ... Switch, 112 ... Radome.

Claims (2)

A receiving antenna for receiving digital broadcast signals;
A redom covering at least part of the antenna;
Receiving means for outputting an arbitrary digital broadcast signal from the digital broadcast signal from the antenna;
Monitoring means for monitoring the reception quality of the digital broadcast signal output from the receiving means;
And a control means for controlling the redome based on the monitoring result of the monitoring means to change the free space loss . The monitoring means monitors a reception level and a carrier-to-noise power ratio (C / N), and the control means controls when the reception level exceeds a reference value and C / N is equal to or less than a reference evaluation value. The receiving apparatus according to claim 1.

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