JP2812194B2 - Satellite communication earth receiving station equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a satellite communication earth receiving apparatus for receiving a signal relayed and transmitted by a satellite relay station, and more particularly to an AFC (automatic frequency control) and AGC.
(Automatic gain control).

[0002]

2. Description of the Related Art SCPC (Sin
In the frequency arrangement of the "gle Channel PerCarrier" system, audio channels are arranged at a frequency interval of 45 kHz, and the frequency interval of 45 kHz is extremely narrow for a radio frequency in the GHz (GHz) band at which these channels are transmitted. Demodulation at the earth receiving station is performed by PSK (Phase Shift Keyin).
g) Since demodulation of modulation is required and synchronous detection is required, there is an extremely strict requirement for frequency accuracy in reception.

Further, SPADE (SCPC PCM m
ultra Access De-mand assig
In the nment Equipment (Central Equipment) method, CSC (common signalli) for performing communication communication is used.
ng channel) is constantly transmitted from the controlling earth station via a satellite. The CSC is used to transmit communications (eg, channel assignment) from the controlling earth station to earth receiving stations belonging to the group. Note that the CSC is transmitted as a continuous wave for the convenience of AFC, but all other communication channels are transmitted as burst waves.

FIG. 2 is a block diagram showing the configuration of a conventional earth receiving station, in which a radio frequency (G
(Hz band) is converted into a signal of the first intermediate frequency by the first frequency converter 2 and distributed to the control receiver 5 and the channel receiver 6 via the distributor 3. The control receiver 5 and the channel receiver 6 have many identical parts in their constituent parts, and these identical parts are represented by the same reference numerals. Is connected by a hyphen. For example, reference numeral 41-5 represents the second intermediate frequency amplifier 41 in the control receiver 5.

[0005] The control receiver 5 receives the CSC, and
And generates a first local oscillation frequency that is phase-synchronized with the carrier frequency of the first frequency converter and supplies the first local oscillation frequency to the first frequency converter 2. For example, the frequency at the carrier frequency of the CSC and F _pr, is converted to the frequency of the first local oscillator (VCO 44) when the F _1, the carrier frequency at the output of the first frequency converter 2 is in F _pr -F ₁ . Assuming that the frequency synthesizer 48 of the control receiver 5 outputs the second local oscillation frequency of the frequency f _2p ,
At the input point of the second intermediate frequency amplifier 41, the carrier frequency of the CSC becomes F _pr −F ₁ −f _2p . Second intermediate frequency amplifier 4
_Assuming that the center frequency of 1 is F ₂ , F _pr −F ₁ −f _2p = F
_When f _2p is set to be ₂ ... (1), CS
The C signal is amplified and supplied to the demodulation unit 42.

[0006] phase detection is performed with respect to the signal of the demodulation unit 42 in the frequency F _2, if there is a frequency deviation F _1, it appears as a frequency deviation at the output of the second intermediate frequency amplifier 41-5, demodulator 42 Is detected as a phase error, and this phase error is supplied to VC through a low-pass filter 43.
Controls O 44, the output F ₁ of VCO44 to the carrier frequency F _pr of CSC to phase lock while maintaining the relation of equation (1). That is, the phase-locked loop is VCO44-first
Frequency converter 2-second frequency converter 40-second intermediate frequency amplifier 41-demodulator 42-low pass filter 43-VC
OCO 44 is used, but since the pull-in range of this phase locked loop is extremely narrow, a crystal oscillator with high frequency accuracy is used as VCO 44. The output level of the second intermediate frequency amplifier 41-5 is detected by the level detector 45, and the output of the level detector is supplied as a signal for feedback controlling the gain of the first frequency converter 2.

When the channel receiver 6 receives the radio frequency F _cr , the channel frequency becomes F _cr -F ₁ at the input point of the second frequency converter 40-6, and the frequency synthesizer 48-6 is changed to the frequency f _2c . And set F _cr −F ₁ −f _2c =
If so becomes F ₂ ···· _(2), it is possible to correctly receive the channel frequency of F _cr. Equation (1),
From (2), only the frequency of the frequency synthesizer 48 is set so that F _pr −F _cr = f _2p −f _2c , and the channel receiver 6 does not need AFC and AGC.

[0008] The channel receiver 6 is also always waiting for the CSC. When the reception frequency is designated by the CSC, the designation is input to the data processing unit 46 via the demodulation unit 42,
The data processing unit 46 controls the logic unit 47-6 to set the frequency of the frequency synthesizer 48-6 to a frequency corresponding to the specified reception frequency. When the number of channels simultaneously received by the earth receiving station increases, the number of channel receivers 6 is increased as shown in FIG.

[0009]

Since the conventional earth receiving station as described above has only one control receiver, there is a problem that if the control receiver fails, the operation of the entire earth receiving station stops. . If a spare is provided in the control receiver in order to avoid this problem, the spare control receiver becomes useless as long as the normal control receiver has no failure. The object of the present invention is to solve such problems in the prior art,
It is an object of the present invention to provide a satellite communication earth receiving station device in which the operation of the earth receiving station does not stop even when the control receiver fails.

[0010]

SUMMARY OF THE INVENTION A satellite communication earth receiving station according to the present invention comprises a plurality of receivers which can be used both as a control receiver and as a channel receiver. That is, a wideband frequency converter for converting a signal transmitted from a satellite relay station into a signal of a first intermediate frequency,
It receives the output of this wideband frequency converter, receives a continuously transmitted CSC signal, generates a first local oscillation frequency that is phase locked to the carrier frequency of this CSC, and sends it to the first frequency converter. A plurality of receivers that operate as a control receiver to supply or a channel receiver that receives an arbitrary communication channel transmitted as a burst signal, and one of the plurality of receivers is used as a control receiver. And means for operating the other as a channel receiver.

[0011]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram showing an embodiment of the present invention. In the drawing, the same reference numerals in FIG. 32 denote the same or corresponding parts, and a description of the same parts as those in FIG. 32 will be omitted. The first frequency converter 2 includes a low-noise amplifier 20 that amplifies a signal received by the antenna 1 at a radio frequency, and a first mixer 2
1 and a broadband intermediate frequency amplifier 22. The output of the first frequency converter 2 is supplied to a plurality of receivers 4a, 4b, 4c via a distributor 3. The output of the VCO 44 of each of the receivers 4a, 4b, 4c is supplied to the first selector 8a, and the output of the level detector 45 is supplied to the second selector 8a.
b.

Which of the plurality of receivers 4 is to be used as a control receiver and which is to be used as a channel receiver is determined, for example, from a host computer (not shown) through the terminal 7. Controlled. When the receiver 4a is a control receiver and the receiver 4b is a channel receiver, the host computer receives the signal from the receiver 4a via the terminal station 7a.
When a command to receive the CSC carrier frequency is given to the data processing unit 46-4a of the second unit, the logic unit 47-4 according to the command
a sets the second local oscillation frequency (f _{2p in} the example of the formula (1)) for receiving the frequency in the frequency synthesizer 48-4a.

At the same time, the selectors 8a and 8b are controlled so that the output of the VCO 44-4a of the receiver 4a and the level detector 45 are controlled.
-4a is connected to the first frequency converter 2. The phase error output generated by the demodulation unit 42 is
To form a phase locked loop of the VCO 44. On the other hand, when a command to receive CSC is given to the data processing unit 46-4b of the receiver 4b via the terminal station 7b,
The receiver 4b enters the CSC standby reception state.

When a specific channel is instructed by the CSC, the instruction enters the data processing unit 46-4b from the demodulation unit 42-4b, and the data processing unit 46-4b outputs the CS signal.
C through the logic unit 47-4b so as to receive the specific channel designated by C.
control b. While the receiver 4b is receiving a specific channel, the receiver 4c waits for and receives the CSC.

If the receiver 4a fails, the receiver 4b is used as a control receiver under the control of the host computer. At this time, the receiver 4c waits for and receives the CSC. That is, in this case, the number of channel receivers is reduced by one from the earth receiving station, but the entire receiving station does not become inoperable unlike the conventional apparatus. Note that the failure of the receiver 4a is, for example, the VCO 44
In the case where the failure is -4a, the receiver 4a can be used as a channel receiver, so that the receiver 4b is used as a control receiver, and the receiver 4a is only used as a channel receiver. The function of the earth receiving station does not decrease at all.

[0016]

As described above, in the satellite communication earth receiving station apparatus of the present invention, the control receiver for receiving the carrier frequency of the CSC and generating the first local oscillation frequency at the satellite communication earth receiving station has failed. Even in this case, there is an effect that the entire earth receiving station can be prevented from becoming inoperable.

[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 a configuration of a conventional device.

FIG. 3 is a block diagram showing a configuration of a conventional device.

[Explanation of symbols]

 Reference Signs List 2 first frequency converter 3 distributor 4 receiver 7 terminal device 8a first selector 8b second selector 40 second frequency converter 41 second intermediate frequency amplifier 42 modulator 43 low-pass filter 44 VCO 45 level detector 46 Data processing unit 47 Logic unit 48 Frequency synthesizer

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁶ , DB name) H04B 7/14-7/22

Claims (2)

(57) [Claims] 1. A method for receiving a signal transmitted from a satellite relay station.
For receiving a radio frequency signal transmitted from a satellite relay station in a first intermediate
A first frequency converter for converting the signal into a frequency signal; an output of the first frequency converter being input and used for satellite communication
SCPC (Single Channel Pe)
r Carrier) C that is continuously transmitted in the system
SC (Common Signaling Chan)
nel), and the position is relative to the carrier frequency of this CSC.
Generating a phase locked first local oscillation frequency to generate the first local oscillation frequency;
As a control receiver to supply to the frequency converter, or as S
Channel receiver for receiving an arbitrary channel of the CPC system
A plurality of receivers operating as a receiver, and one of the plurality of receivers is controlled as described above.
Operating as a receiver, and the other as the channel receiver
Means to operate asEquipped,Each receiver of the plurality of receivers, A second input from the first frequency converter via a distributor;
1 The signal of the intermediate frequency is converted into the second intermediate frequency by the second local oscillation frequency.
A second frequency converter that converts the signal into an inter-frequency signal; A predetermined frequency of the signal from the second frequency converter
A second intermediate frequency amplifier for amplifying the band signal, Demodulation for demodulating the signal from the second intermediate frequency amplifier
Department, The oscillation frequency of the VCO that generates the first local oscillation frequency
Is fed by the phase error signal detected by the demodulator.
Means to control the back, A level for detecting an output level of the second intermediate frequency amplifier;
Detector A data processing unit to which an output of the demodulation unit is input; A frequency synthesizer for generating the second local oscillation frequency
The, The oscillation frequency of this frequency synthesizer is processed by the data processing.
Means for setting by a signal from the unit,  A satellite communication earth receiving station device comprising: And means for operating one of the plurality of receivers as the control receiver and operating the other as the channel receiver from a host computer operating as a control receiver. Sending a signal to a data processing section of the dual-use receiver to control the synthesizer of the receiver to generate a second local oscillation frequency for receiving the carrier frequency of the CSC;
Is connected as the first local oscillation frequency of the first frequency converter via a first selector, and the output of the level detector of the receiver is connected to the gain of the first frequency converter via a second selector. connecting a as a signal for feedback controlling the satellite earth receiving station apparatus as in claim 1, wherein said.