JP3039046B2 - Receiver for satellite communication - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a receiver for satellite communication, and more particularly to a receiver for receiving a signal from a satellite received by an antenna.
The present invention relates to a satellite communication receiver in which a conversion unit for converting a signal and a demodulation unit for demodulating an IF signal are separated via a coaxial cable.

[0002]

2. Description of the Related Art Conventionally, this type of satellite communication receiving apparatus has
As shown in FIG. 2, a conversion unit 40 installed on the antenna side and a demodulation unit 50 installed indoors are connected by a coaxial cable 30.

[0003] A conversion unit 40 includes a low-noise amplifier 41 for amplifying a received signal received by an antenna, and a mixer 43 for converting the received signal into an IF signal by mixing with a local oscillation signal from a local oscillator 42. , An IF amplifier 44 for amplifying the IF signal to a predetermined level, and an IF signal Si to the coaxial cable 30 and a frequency reference signal Sf and power supply current transmitted from the demodulation unit 50 via the coaxial cable 30. It has a demultiplexing / synthesizing unit 45 for separating each power supply, and a power supply unit 46 for receiving the separated power supply current and supplying power to each unit in the unit.

Here, the local oscillator 42 generates a highly stable local oscillation signal based on the frequency reference signal Sf sent from the demodulation unit 50. In this case, the frequency reference signal S
f is set to a frequency sufficiently lower than that of the IF signal so as not to interfere with the IF signal.

The demodulation unit 50 includes a demodulation section 51 for demodulating an IF signal, a reference signal generation section 52 for generating a frequency reference signal Sf, a power supply section 53, and a coaxial cable 30.
And a splitter 54 that separates the IF signal Si sent from the conversion unit 40 via the frequency converter 40 and superimposes the frequency reference signal Sf and the power supply current and sends the signal to the coaxial cable 30.

[0006]

In the above-mentioned conventional satellite communication receiver, the length of the coaxial cable changes depending on the installation location of the conversion unit and the demodulation unit, and the cable loss also changes. For this reason, when the device is installed, the I
The F signal output level is adjusted. However, when the installation location of each unit is changed, level adjustment is required each time. Also, if the coaxial cable is too long, an auxiliary amplifier (booster) must be added,
Conversely, if the coaxial cable is too short, the input level of the IF signal to the demodulation unit exceeds the allowable value, so that there is a problem that an attenuator must be inserted on the input side of the demodulation unit.

[0007] It is an object of the present invention to provide a satellite communication receiver capable of always keeping the level of an IF signal input to a demodulation unit constant even when the length of a coaxial cable changes.

[0008]

According to the present invention, there is provided a satellite communication receiving apparatus in which a conversion unit for converting a received signal into an IF signal and a demodulation unit for demodulating the IF signal are separately installed via a coaxial cable. In the receiving device, the conversion unit is configured to transmit the IF signal at an output level corresponding to an IF level control signal, and an output signal of the IF amplification unit to the coaxial cable and to output the IF signal from the demodulation unit. A demultiplexing unit that separates the transmitted frequency reference signal; and an IF level control unit that detects the level of the frequency reference signal separated by the demultiplexing unit and generates the IF level control signal. The demodulation unit detects a level of an IF signal sent from the conversion unit and a reference signal generation unit that generates the frequency reference signal. I for generating a reference level control signal Te
An F level detection unit, a reference level control unit that controls the level of a frequency reference signal output from the reference signal generation unit according to the reference level control signal, and an IF signal transmitted from the conversion unit. A demultiplexing unit for transmitting a frequency reference signal output from the reference level control unit to the coaxial cable.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, the present invention will be described with reference to the drawings.

FIG. 1 is a block diagram showing one embodiment of the present invention, in which a conversion unit 10 installed on the antenna side,
Coaxial cable 3 with demodulation unit 20 installed indoors
Connected by 0.

Here, the conversion unit 10 includes a low-noise amplifier 11 for amplifying the received signal, a mixer 13 for mixing the local signal from the local oscillator 12 and frequency-converting the received signal into an IF signal, An IF amplifier 14 for amplifying the signal to an output level corresponding to the control signal C1, an IF signal Si to the coaxial cable 30, a frequency reference signal Sf transmitted from the demodulation unit 20 via the coaxial cable 30, Demultiplexer 1 for separating power supply current
5, a reference level detector 16 for detecting the level of the frequency reference signal Sf separated by the splitter / synthesizer 15 to generate the control signal C1, and a buffer for amplifying the separated frequency reference signal Sf to a constant level. It has an amplification unit 17 and a power supply unit 18 that receives the separated power supply current and supplies power to each unit in the unit.

Here, the local oscillation section 12 generates a highly stable local oscillation signal based on the frequency reference signal Sf sent from the demodulation unit 20. The frequency reference signal Sf is
In order not to interfere with the IF signal Si, the frequency is set to be sufficiently lower than that of the IF signal.

The demodulation unit 20 includes a reference signal generator 21 for generating a frequency reference signal and a coaxial cable 30.
A splitter / synthesizer 22 that separates the IF signal Si transmitted through the multiplexing unit, superimposes the frequency reference signal Sf and the power supply current, and sends the signal to the coaxial cable 30; A demodulation unit 23 for demodulating Si and an IF signal S separated by the demultiplexing unit 22
IF level detector 24 for detecting the level of i to generate a control signal C2, and reference level control for receiving the frequency reference signal output from reference signal generator 21 and controlling the level of the frequency reference signal in accordance with control signal C2 And a power supply unit 26 for supplying power.

Next, the operation will be described.

The IF level detector 24 of the demodulation unit 20
Detects the level of the IF signal Si sent from the conversion unit, and generates a control signal C2 to increase the level of the frequency reference signal Sf sent to the conversion unit when the IF signal level decreases, When the IF signal level rises, a control signal C2 is generated so as to lower the level of the frequency reference signal Sf sent to the conversion unit 10 and sent to the reference level control unit 25.

On the other hand, the reference level detection section 16 of the conversion unit 10 detects the level of the frequency reference signal Sf sent from the demodulation unit 20, and when the level of the frequency reference signal decreases, the IF amplification section 14 A control signal C1 is generated so as to increase the output level and, when the level of the frequency reference signal rises, so as to decrease the output level of the IF amplifying section, and sends it to the IF amplifying section.

In this way, even if the length of the coaxial cable changes, the level of the IF signal input to the demodulation unit can always be kept constant.

[0018]

As described above, according to the present invention, on the demodulation unit side, the level of the IF signal transmitted from the conversion unit via the coaxial cable is detected.
The level of the frequency reference signal is controlled in accordance with the level of the F signal and transmitted to the conversion unit, and the conversion unit detects the level of the frequency reference signal transmitted from the demodulation unit via the coaxial cable, By controlling the output level of the IF signal according to the level of the frequency reference signal, the level of the IF signal input to the demodulation unit can be kept constant regardless of the length of the coaxial cable. Therefore, it is not necessary to adjust the level of the IF signal each time the apparatus is installed or whenever the installation location of each unit is changed.

[Brief description of the drawings]

FIG. 1 is a block diagram showing one embodiment of the present invention.

FIG. 2 is a block diagram showing an example of a conventional satellite communication receiver.

[Explanation of symbols]

 Reference Signs List 10 conversion unit 14 IF amplifying unit 15, 22 demultiplexing unit 16 reference level detection unit 20 demodulation unit 21 reference signal generation unit 24 IF level detection unit 25 reference level control unit 30 coaxial cable C1, C2 control signal Si IF signal Sf frequency Reference signal

Continuation of the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) H04B ^7/ 14-7/22 H04B 3/04

Claims (1)

(57) [Claims] 1. A satellite communication receiver in which a conversion unit for converting a received signal into an IF signal and a demodulation unit for demodulating the IF signal are separately installed via a coaxial cable, wherein the conversion unit converts the IF signal into An IF amplifying section for transmitting at an output level corresponding to the IF level control signal;
A demultiplexing unit for transmitting an output signal of the F amplifying unit to the coaxial cable and separating a frequency reference signal transmitted from the demodulation unit; and determining a level of the frequency reference signal separated by the demultiplexing unit. Detect the IF
An IF level control unit for generating a level control signal, wherein the demodulation unit includes a reference signal generation unit for generating the frequency reference signal, and an I / O signal transmitted from the conversion unit.
An IF level detector for detecting a level of an F signal to generate a reference level control signal; a reference level controller for controlling a level of a frequency reference signal output by the reference signal generator in accordance with the reference level control signal. A demultiplexing unit that separates an IF signal sent from the conversion unit and sends a frequency reference signal output by the reference level control unit to the coaxial cable. .