JP3304880B2 - Two-body separated FPU receiving method and receiving apparatus - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a high frequency section for converting an SHF reception signal into an IF signal, a control section for demodulating the IF signal into a video signal or the like, and connecting the high frequency section and the control section. -Separated FPU (field pickup unit) composed of coaxial cables
In the receiving apparatus, even when the cable length L of the coaxial cable is longer than the maximum cable length Lmax, the required S / S
The present invention relates to a two-housing separated FPU receiving method and a receiving apparatus capable of ensuring a sufficient N, and having a small and inexpensive configuration and capable of making the cable length L longer than a maximum cable length Lmax in an emergency or the like.

[0002]

BACKGROUND OF THE INVENTION FIG. 3 is a block diagram of a conventional two-unit separated FPU receiver. In the figure, 2 is a control unit, 1 is a high frequency unit, and 3 is a coaxial cable connecting the control unit 2 and the high frequency unit 1. The control unit 2 has an IGC having an AGC function.
It has an F amplifier 2-5 and a telemeter 2-2 for transmitting the state to the high frequency unit 1.

The high frequency section 1 includes a mixer 1-2 for converting the SHF signal into an IF signal, an IF amplifier 1-3 for amplifying the IF signal to a predetermined level, and a telemeter for transmitting the state to the control section 2. 1-1 and a demultiplexer-synthesizer 1-4. In the high frequency section 1, the mixer 1-2
Converts the input SHF signal to 70 MHz or 130 M
Hz IF signal.

The IF signal is amplified to a predetermined output level by an IF amplifier 1-3, passes through a demultiplexer 1-4, and
The signal is input to the control unit 2 via the coaxial cable 3. Since the length of the coaxial cable 3 is always different depending on the use conditions, the IF signal reaching the control unit 2 is always different. Therefore A
The IF signal is controlled to be always at a constant level by the IF amplifier 2-5 having the GC function.

[0005]

However, in such a conventional two-housing separated FPU receiver, the cable length L is regulated by the IF signal attenuation in the coaxial cable 3, and the cable length L is set to Lmax (for example, , 400 m). As a method of solving this problem, there is a method of changing the coaxial cable 3 to a cable with lower loss. However, there is a problem that the lower loss cable is generally thicker and heavier, so that the mobility is deteriorated. .

As a second method, the AGC in the control unit 2
There is a method of expanding the AGC range of the IF amplifier 2-5 having a function.
Since the predetermined signal-to-noise ratio cannot be secured because the F signal level decreases, it is not practical. Also, as a third method,
Although there is a method of increasing the output level of the IF amplifier 1-3 in the high-frequency unit 1, when the output level of the IF amplifier 1-3 is simply increased, the cable length L of the coaxial cable 3 is L ≧ Lmax.
However, when the cable length is short (for example, 1 m), there is a problem that the IF signal causes intermodulation in the control unit 2 and is not practical.

An object of the present invention is to provide a two-housing separated type FPU receiving method and a receiving apparatus capable of making the cable length L longer than the maximum cable length Lmax in an emergency or the like with a small and inexpensive configuration. It is in.

[0008]

The object of the present invention is to provide a high frequency section for converting an SHF reception signal into an IF signal and a control section for demodulating the IF signal into a video signal or the like, wherein the high frequency section and the control section are provided. in second housing separated FPU receiving apparatus configured in this connecting a coaxial cable bets, a predetermined hysteresis
Based on the cis, comprising: an IF signal level which is demultiplexed into the control unit IF signal level detecting means for detecting, before
The IF signal level detecting means outputs a control signal to the IF in the high frequency section when the detected value is equal to or less than a predetermined value.
And outputting through both telemetry of the controller and the high-frequency portion toward the amplifier, responsive to said control signal, said
A step in which the IF amplifier in the high-frequency section controls the output level.
Is solved by second housing separated FPU reception method characterized by having a flop. In addition, the two-body separated FPU
The receiving method may be such that the display means is outputting a control signal.
Is displayed .
Also, the above-mentioned problem is provided with a high frequency unit for converting an SHF reception signal into an IF signal and a control unit for demodulating the IF signal into a video signal or the like, and the high frequency unit and the control unit are connected by a coaxial cable. Two-frame separated FPU configured by connecting
In the receiving device, the control unit includes an IF amplification unit having an AGC function of amplifying an IF signal input from the high-frequency unit via a coaxial cable and a demultiplexer to a predetermined signal level, and via the coaxial cable. Telemeter means for converting the state of the control unit to a different frequency IF '(telemeter signal) for transmitting the state of the control unit to and from the high frequency unit, and the control unit based on a predetermined hysteresis.
Section detects the IF signal level split into
When the value is equal to or less than a predetermined value, I
And a F signal level detecting means, the high frequency portion, SH
A mixer means for converting the IF signal to enter the F signal, the
I output from the mixer means based on a control signal.
IF amplifying means for amplifying the F signal to a predetermined output, and telemeter means for converting the state of the high-frequency part into a different frequency IF '(telemeter signal) from the previous IF frequency for transmitting the state to the control part If, 2, characterized in that it comprises a branching combining means for multiplexing the telemeter signals to a coaxial cable output from the IF signal and the DC voltage and the telemeter means is amplified by the IF amplifier means The problem is solved by a housing separated type FPU receiver. Also,
The two-casing separated FPU receiving apparatus is outputting a control signal
It is characterized by having display means for displaying the effect .

[0009]

[0010]

According to the present invention, since the above configuration is employed, the level value of the IF signal of the control unit for demodulating into a video signal or the like becomes less than a predetermined value, and the required S / N cannot be secured. In this case, the output power of the high-frequency section IF can be properly amplified, and the S / N of the IF signal reaching the control section can be secured well. Also, the IF in the high frequency section
Since the display means for displaying that the control signal to the amplifier is being output is provided, it is possible to accurately know that the amplifier is operating in the cable length extension mode.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention relates to a high frequency section for converting an SHF reception signal into an IF signal, a control section for demodulating the IF signal into a video signal, and the like, and connecting the high frequency section and the control section. In a two-housing separated FPU receiver constituted by a coaxial cable and a coaxial cable, the cable length L of the coaxial cable
Is longer than the maximum cable length Lmax.
/ N is secured.

[0012]

[Embodiment 1] An embodiment of a two-housing separated FPU receiving apparatus according to the present invention will be described in detail with reference to the drawings. As shown in the block diagram of FIG. 1, a two-housing separated FPU receiving apparatus according to the present invention, a mixer 1-2 for inputting an SHF signal and converting it to an IF signal, and amplifies the IF signal to a predetermined output. IF amplifying means 1-3 and control unit 2
Between the previous IF frequency and another frequency I
Telemeter means 1 for converting to F ′ (telemeter signal)
1, a high-frequency unit 1 having a demultiplexing unit 1-4 for multiplexing an IF signal, a DC voltage, and a telemeter signal on one coaxial cable, and input from the high-frequency unit 1 via a coaxial cable 3. IF amplifying means 2-5 having an AGC function for amplifying an IF signal to a predetermined signal level, and an IF amplifying means for transmitting the state of the control unit 2 to the high frequency unit 1 via the coaxial cable 3. Frequency and another frequency IF '
(Telemeter signal) for converting to (telemeter signal) 2-2
And a control unit 2 having a splitter / synthesizer 2-4 for multiplexing the IF signal, the DC voltage, and the telemeter signal on one coaxial cable. IF amplification means having AGC function 2-
IF level detecting means 2-1 for detecting an IF signal level to the IF signal 5 and outputting a control signal when the IF signal level is equal to or less than a predetermined value; 1 is input to an IF amplifying means 1-3 that amplifies the IF signal in 1 to a predetermined value.

[0013]

Second Embodiment IF Amplifying Means 2- Having AGC Function
IF signal level detecting means 2 for detecting an IF signal level to the control signal 5 and outputting a control signal when this level is equal to or less than a predetermined value.
1, a display means 2-3 for displaying that the control signal from the IF signal level detecting means 2-1 is being output to the IF amplifier 1-3 in the high-frequency section 1 is provided. Know that is operating in extended mode.

Hereinafter, the operation of the two-unit separated FPU receiving apparatus according to the present invention will be described based on the above embodiment. Generally, in the case of a microwave band FPU receiver, the SHF signal is -10d by a mixer circuit in a high frequency section.
It is converted to a Bm IF signal. Thereafter, the power is increased to +13 dBm in the IF amplifier, and transmitted to the control unit via a demultiplexer and a coaxial cable.

Normally, the IF signal frequency uses 130 MHz, and the coaxial cable uses 5D-2W. The relationship between the cable length of the coaxial cable and the IF reaching level to the control unit in this case will be described with reference to FIG. That is, under the normal use condition, the loss in the coaxial cable of 5D-2W in the case of the IF frequency is 1 dB / 10 m. The connection cable length from the high frequency unit to the control unit of the FPU device is from 0 m to 4
00m, the IF signal level reaching the control unit changes by 40 dB from +13 dBm to -27 dBm.

The IF signal level is kept constant at 0 dBm by an IF amplifier with AGC in the control section. Since the noise level after the IF stage in the control unit is constant at about -90 dBm, even if the cable length is 400 m, the required S /
N of 60 dB is satisfied. However, if the cable length is 400
m, the IF signal level in the control unit is -27d
On the other hand, the noise level is equal to or less than Bm, but the noise level in the control unit is constant, so that a predetermined S / N cannot be secured.

Under the above circumstances, in the two-cassette separated FPU receiving apparatus according to the present invention, the state of the high-frequency unit 1 is changed between the control unit 2 and the frequency IF '(telemeter signal), the IF signal and the DC voltage. Is input to the control unit 2 via one coaxial cable 3 and the demultiplexing / synthesizing unit 1-4, and the input IF signal is input by the IF amplifying unit 2-5 having the AGC function provided in the control unit 2. Is amplified to a certain signal level, and the amplified output of the IF amplifying means 2-5 having the AGC function is detected by the IF input level detecting means 2-1.
When the detection signal level detected by the F input level detecting means 2-1 is equal to or less than a predetermined value, the IF input detecting means 2
-1 to control the IF amplifier 1-
3 in accordance with the control signal.
Since the F signal is amplified to a predetermined value, a control signal is output when the control unit arrival level detected by the IF input detection circuit 2-1 in the control unit 2 becomes -27 dBm or less. Since the IF signal in the high frequency unit 1 is amplified to a predetermined value by a signal, the level value of the IF signal of the control unit 2 for demodulating the signal into a video signal or the like becomes equal to or less than the predetermined value, and the required S / N is not secured. In this case, the IF signal of the high-frequency unit 1 can be properly amplified, and the S / N of the IF signal reaching the control unit can be secured well.

Further, since the AGC voltage may be compared with a reference value and output as the detection voltage, the IF input detection circuit 2-1 can be constituted by a very small and simple circuit. Moreover, it is possible to provide a relay so that an amplifying transistor can be cascade-connected to the final stage of the IF amplifier 1-3 in the high-frequency section by the control signal, and it is also possible to amplify and output by about 10 dB. , Since the IF signal arrival level in the control unit 2 becomes high,
A predetermined S / N is ensured, while the IF input detection circuit 2-1 is provided with a 15 dB hysteresis circuit,
The chattering phenomenon caused by the operation of the above circuit can be effectively avoided.

The IF signal level to the IF amplification means 2-5 having the AGC function is detected, and if the level is equal to or less than a predetermined value, a control signal is output after the IF signal level detection means 2-1. IF signal level detecting means 2
-1 in a high-frequency section receiving a control signal from -1
Since the display means 2-3 for displaying that the control signal to the C-3 is being output is provided, it can be easily known that the cable length is operated in the extension mode.

[0020]

According to the present invention, as described above, if the value of the IF signal level to the control unit falls below a predetermined value and the required S / N is not ensured, the high frequency unit IF output power is increased. This allows
The S / N of the IF signal reaching the control unit is secured.

Further, it is possible to know from the display means that the apparatus is operating in the cable length extension mode.

[Brief description of the drawings]

FIG. 1 is a block diagram showing one embodiment of a two-casing separate FPU receiving apparatus according to the present invention.

FIG. 2 is a graph showing a relationship between a cable length of a coaxial cable and an IF reaching level to a control unit.

FIG. 3 is a block diagram illustrating an example of a conventional two-casing separated FPU receiving apparatus.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 High frequency part 1-1 Telemeter 1-2 Mixer means 1-3 IF amplification means 1-4 Demultiplexing-synthesis means 2 Control part 2-1 IF input level detection means 2-2 Telemeter 2-3 Display means 2-4 Demultiplexing Synthesizing means 2-5 IF amplifying means having AGC function 3 Coaxial cable

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) H03G 1/00-3/34

Claims (4)

(57) [Claims] 1. A method for converting an SHF reception signal into an IF signal.
To demodulate the high-frequency part and IF signal to video signal etc.
A control unit, wherein the high-frequency unit and the control unit are coaxial cables.
Cable-separated FPU reception with two cables
In the device,Based on the predetermined hysteresis, Demultiplexed by the control unit
IF signal level detection meansButDetectionDo
Steps and The IF signal level detecting means detects Predetermined
If it is less than the value,The control signal is transmitted to the I
Towards F amplifierControl unit and high-frequency unit
ThroughOutputting, In response to the control signal, an IF amplifier in the high frequency section
 Control output levelHaving stepsCharacterized by
A two-case separated FPU receiving method. (2)The two-body separated FPU receiving method includes: The display means displays information indicating that a control signal is being output.
Having the step of 2. The method according to claim 1, whereinToDescription
2. The FPU receiving method of the two cases separated from each other. 3. A method for converting an SHF reception signal into an IF signal.
To demodulate the high-frequency part and IF signal to video signal etc.
A control unit, wherein the high-frequency unit and the control unit are coaxial cables.
Cable-separated FPU reception with two cables
In the apparatus, the control unitIsFrom the high-frequency section via a coaxial cable and a demultiplexer
To amplify the input IF signal to a certain signal level
An IF amplifying means having an AGC function; and
IF frequency and another frequency IF 'to communicate between
(Telemeter signal),Based on a predetermined hysteresis, the signal is split by the control unit.
Detected IF signal level, and the detected value
If it was below, IF signal level for outputting control signal
Detection meansAnd  The high frequency sectionIsMixer means for inputting the SHF signal and converting it to an IF signal;Based on the control signal, Output from the mixer means
IF amplifying means for amplifying the IF signal to a predetermined output, and transmitting the state of the high-frequency unit to the control unit.
Destination IF frequency and another frequency IF '(telemeter signal
), An IF signal amplified by the IF amplifying means, a DC voltage,
The telemeter signal output from the telemeter means is 1
Multiplexing means for multiplexing on a single coaxial cableWith
DoA FPU receiving apparatus with two separate housings, characterized in that: (4)The two-body separated FPU receiving apparatus includes: Display means for displaying that the control signal is being output This
4. The method according to claim 3, whereinToFPU receiver with two separate housings as described
Communication device.