JPS63190434A - Repeater for satellite - Google Patents

Abstract

PURPOSE:To transmit both a TDMA signal and an SCP signal or the like without deterioration in transmission by providing an amplitude limit circuit clipped by two variable gain means to the prestage of a switch matrix, and an amplitude limit circuit having the variable gain means at the pre-stage to the post- stage of the switch matrix. CONSTITUTION:The switch matrix 4 connecting switchingly an output of receivers 41-4M to the input of transmitters 51-5N is provided, at least one receiver includes a 1st amplitude limit circuit 3 having a 1st variable gain means 10 at its pre-stage and having a 2nd variable gain means 11 at its post- stage, and at least one transmitter includes a 2nd amplitude limit circuit 6 having a 3rd variable gain means 12 at its pre-stage. Then the 1st, 2nd and 3rd variable gain means are controlled in response to a reception signal by remote control. Thus, even when the reception signal consists of the mixture of a time division multiple access (TDMA) signal and a Single Channel Per Carrier(SCPC) signal or only the SCPC signal, the switch matrix input level is controlled to attain transmission without deteriorating in transmission.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a satellite repeater equipped with a switch matrix and using multi-beams, and particularly to a case where signals with different level differences are simultaneously transmitted. This article relates to a satellite repeater that enables transmission without causing interference deterioration or deterioration due to nonlinear characteristics.

[Conventional technology]

FIG. 2 is a block diagram showing an example of a conventional satellite repeater using multiple beams. This conventional example includes M receivers 21, 22, .
．． 32, . . . , 3N, and a switch control circuit 5 that is connected to the switch matrix 4 and controls it. The receivers 21, 22, . . . , 2M each include a receiving antenna 1, an amplification/frequency conversion circuit 2, and an amplitude limiting circuit 3, and the transmitters 31, 32, . It includes a frequency conversion/amplification circuit 7, a high-output amplification circuit 8, and a transmission antenna 9.

In Fig. 2, a signal received at frequency F from a satellite communication earth station is amplified by an amplification/frequency conversion circuit 2 via receivers 21, 22, . . . , 2M receiving antennas 1. , converted to frequency f. And this frequency f
The converted signal is input to the amplitude limiting circuit 3. This amplitude limiting circuit 3 functions to keep the output level constant even if the reception level changes due to rain or the like. The signal limited to a certain level is connected to one or more of the N output terminals in the switch matrix 4 by a control signal from the switch control circuit 5.

The level of the output signal from the switch matrix 4 fluctuates depending on the connection path within the switch matrix 4.

In order to suppress this level fluctuation, the amplitude limiting circuit 6 maintains the level at a constant level. This signal is then frequency converted and
The signal is sent to a transmitting antenna 9 via an amplifier circuit 7 and a high-output amplifier circuit 8 .

[Problem that the invention seeks to solve]

In the conventional satellite repeater mentioned above, TDMA (
In addition to signals that do not require linear characteristics such as time division multiple access (time division multiple access) signals (hereinafter referred to as TDMA signals),
Single Channel Per Ca
When attempting to transmit a signal (hereinafter referred to as a 5cpc etc. signal) that requires linear characteristics such as a To avoid characteristic effects, it must be backed off and used in the linear region. In this case, the input level must be reduced, and as a result, the switch matrix input level of the switch matrix 4 is reduced.

Now let the isolation between paths in the switch matrix 4 be I (dB), and there are M-1 equal amplitude signals.

Considering the case of transmitting one signal with a C (dB) level lower than this, D = tox due to multiple wave input
log+o(M1) (dB) ---
---- (1) Isolation deterioration occurs, and due to the input level difference, isolation deterioration of C (dB) occurs. As a result, the D/U ratio (desired signal to interfering signal ratio) between the low-level signal and the interference wave deteriorates to a value given by the following equation.

D/U = I - (D + C) (dB) - - - Song (2) If there is a level difference C in the switch matrix input level as shown above, there is no isolation for low level signals. This method has the drawback of causing transmission degradation due to interference waves caused by the degradation.

An object of the present invention is to eliminate the above-mentioned drawbacks by controlling the switch matrix input level when M received signals are a mixture of TDMA etc. signals and 5cpc etc. signals or consist only of 5cpc etc. signals. The object of the present invention is to provide a satellite repeater that enables transmission without causing transmission deterioration.

Means for Solving Problem C] The present invention provides a satellite repeater including a plurality of receivers, a plurality of transmitters, and a switch matrix that switches and connects the output of the receiver to the input of the transmitter. At least one of the receivers includes a first amplitude limiting circuit having a first variable gain means at a front stage and a second variable gain means at a rear stage, and at least one of the transmitters includes a third amplitude limiting circuit at a front stage and a second variable gain means at a rear stage. a second amplitude limiting circuit having variable gain means, the first, second and third variable gain circuits including control means controlled in response to a received signal or by remote control; .

Further, in the present invention, it is preferable that the variable gain means is a variable attenuator.

[Operation] The first gain variable means, for example, a variable attenuator, allows TDMA
In a receiver receiving an equal signal, the input level is controlled so that the first amplitude limiting circuit operates in the amplitude limiting characteristic region, and in a receiver receiving a 5 cpc equal signal, the first amplitude limiting circuit is controlled in a linear manner. In order to operate in the characteristic region, the amount of attenuation is made larger than in the case of TDMA or other signals to control the human power level. Then, in the case of a signal such as 5 cpc, the second variable gain means, for example, a variable attenuator, reduces the amount of attenuation by an amount greater than that in the case of a signal such as TDMA with the first variable attenuator, and T D, M A signal and 5cpc
Even in the case of equal signals, the input levels to the switch matrix are made equal.

On the other hand, in the transmitter, the third variable gain means
In the case of a signal such as TDMA, controlling the input level so that the second amplitude limiting circuit operates in the amplitude limiting characteristic region,
In the case of a signal such as 5 cpc, the input level of the second amplitude limiting circuit is controlled so that the second amplitude limiting circuit and the high output amplifier circuit operate in a linear characteristic region.

Therefore, even if the M received signals include a mixture of TDMA signals and 5CPC signals, the switch matrix input levels become equal, and transmission deterioration due to level differences can be eliminated. Furthermore, in the case of a 5CPC signal, it is also possible to eliminate transmission degradation due to nonlinear characteristics in the amplitude limiting circuit and high output amplifier circuit in the transmitter.

Thus, according to the present invention, the TDMA etc. signal and 5 cpc
It becomes possible to transmit both equal signals with reduced transmission deterioration.

Note that the first, second, and third variable gain means are configured to adjust the gain for the 5 cpc signal based on the receiver and transmitter for the TDMA signal, for example, when the reception and transmission of the TDMA signal are fixed. It is sufficient to match the above-mentioned levels of the receiver and transmitter, and in this case, it is sufficient to provide only the receiver and transmitter for signals such as 5 cpc.

〔Example〕

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a professional configuration diagram showing an embodiment of the present invention. In this embodiment, a plurality of M receivers 41, 42...4
M, a plurality of N transmitters 51, 52, . . . , 5N,
The outputs of the receivers 41, 42, . . . , 4M are sent to the transmitters 51, 42, .
A switch matrix 4 having a scale of MXN is switched and connected to inputs of 52, . . . It also includes a variable attenuator control drive circuit 13 for controlling the variable attenuator.

Each of the receivers 41, 42, . . . , 4M includes a receiving antenna 1, an amplification/frequency conversion circuit 2 that amplifies the received signal and performs a predetermined frequency conversion, and an output of the amplification/frequency conversion circuit 2. a variable attenuator 10 as a first variable gain means that applies a predetermined amount of attenuation to the output; an amplitude limiting circuit 3 that limits the amplitude of the output of the variable attenuator 10; variable attenuator 1 as a second variable gain means which gives and inputs into switch matrix 4
1. In addition, each transmitter 51, 52,...
, 5N are respectively connected to the output terminal of the switch matrix 4, and a variable attenuator I2 as a third variable gain means which gives a predetermined amount of attenuation to the input signal, and a predetermined amount to the output of the variable attenuator 12. an amplitude limiting circuit 6 that limits the amplitude of the amplitude, a frequency converting/amplifying circuit 7 that performs predetermined frequency conversion and amplification on the output signal of the amplitude limiting circuit 6, and a power amplifying circuit that converts the output of the frequency converting/amplifying circuit 7. The high-power amplifier circuit 8 includes a high-power amplifier circuit 8 and a transmitting antenna 9 that transmits an output signal from the high-power amplifier circuit 8. The output of the variable attenuator control drive circuit 13 is for each variable attenuator 10.1.
1 and I2 control terminals.

A feature of the present invention is that in FIG.
1 and 12, and a drive circuit 13 for controlling the variable attenuator.

Next, the operation of this embodiment will be explained. The basic reception and transmission operations of this embodiment are the same as those of the conventional example shown in FIG.

First, for TDMA and other signals where nonlinear characteristics are not a problem, in order to keep the switch matrix input level constant against reception level fluctuations due to rain, etc., the amplitude limiting circuit 3 operates as an input that operates in the amplitude limiting characteristic region. So that
The amount of attenuation of the variable attenuator 10 is set. Let the amount of attenuation at this time be /'z (dB). Also, if the output level of the amplitude limiting circuit 3 at this time is P z (dBm), and the attenuation amount of the variable attenuation P, 11 is 81 (dB), the switch matrix person Kareher P3 is P 3 = P z B + ( dBm)
−−−−−−−−−・−−−−−−(3).

On the other hand, for a receiver on a path that transmits a signal such as 5 cpc that requires linear characteristics, the input level is adjusted so that the attenuation amount of the variable attenuator 10 is increased so that the amplitude limiting circuit 3 operates in the linear characteristic region. Set. The amount of attenuation at this time is A,
(dB), and the output level of the amplitude limiting circuit 3 is assumed to be Pza. If the attenuation amount of the variable attenuator 10 is set as described above and at the same time the attenuation amount of the variable attenuator 11 is set to Bz (dB), the switch matrix input level P , a (
dam) is given by the following formula.

P, a = Pza B2 (dBm) --
−−−−−−−−(4) When attempting to transmit the two types of signals mentioned above at the same time, the DZU ratio is not degraded by interference waves generated by coupling between paths within the switch matrix 4. In order to achieve this, it is sufficient to make the multiple input levels input to the switch matrix 4 equal. This corresponds to reducing the value of C in equation (2), and equation (3)
), and the switch matrix input levels P3 and P3a shown in (4) may be made equal. That is, 5
When transmitting a signal such as CPC, the amount of attenuation of the variable attenuator 11 may be controlled to be reduced by ΔB (dB) shown below compared to when transmitting a signal such as TDMA.

ΔB=B, -Bz =pz -Pza (dB) -
-(5) On the other hand, on the output side of switch matrix 4,
There are level fluctuations due to path deviations within the switch matrix 4. For signals such as TDMA that have relatively strong nonlinear characteristics, the amplitude limiting circuit 6 is operated in the amplitude limiting characteristic region, and the input level of the high output amplifier circuit 8 is controlled to a constant value. For signals such as 5cpc that require linear operation,
The input of the amplitude limiting circuit 6 is made small, and the amount of attenuation of the variable attenuator 12 is controlled so as to operate linearly. At this time, the high output amplifier 8 is also made to operate linearly.

In the above embodiment, each receiver and each transmitter are provided with a variable attenuator, but if the receiver and transmitter that handle TDMA or other signals are fixed, this fixed reception The same effect can be obtained by providing variable attenuation only for the receiver and transmitter that handle signals such as 5CPC, without providing variable attenuation for the receiver and transmitter.

Further, although a variable attenuator is used as the variable gain means, the same effect can be obtained by using a variable gain amplifier and controlling its gain.

Furthermore, the variable gain means can also be controlled by remote control from the earth station.

Furthermore, automatic control is possible by controlling the variable gain means according to the received signal level.

〔Effect of the invention〕

As explained above, the present invention includes an amplitude limiting circuit sandwiched between two variable gain means at the front stage of a switch matrix,
By including an amplitude limiting circuit with variable gain means at the front stage after the switch matrix, the amplitude limiting function can keep the switch matrix input level constant even if the received signal level of the TDMA signal changes due to rain, etc. Even when the received signal is a mixture of multiple TDMA signals and multiple 5cpc signals, interference degradation due to coupling between paths in the switch matrix and nonlinear characteristics in amplitude limiting circuits and high output amplifier circuits can be avoided. This has the effect of making it possible to transmit both TDMA and other signals and 5CPC and other signals without suffering from transmission deterioration.

Furthermore, even in the case of only a plurality of 5 cpc signals, transmission is possible without suffering from transmission deterioration due to nonlinear characteristics in the amplitude limiting circuit and high output amplifier circuit.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing an embodiment of the present invention. FIG. 2 is a block diagram showing a conventional example. ■... Reception antenna, 2... Amplification/frequency conversion circuit, 3.6... Amplitude limiting circuit, 4... Switch matrix, 5... Switch control circuit, 7... Frequency conversion/amplification Circuit, 8... High output amplifier circuit, 9... Transmission antenna, 10.11.12... Variable attenuator, 13...
・Drive circuit for variable attenuator control, 21.22, -・-12
M, 41.42, -14M...receiver, 31.32,
-13N, 51.52, -15N...Transmitter.

Claims (2)

[Claims] (1) Multiple receivers (41 to 4M) and multiple transmitters (
51 to 5N) and a switch matrix (4) for switching and connecting the output of the receiver to the input of the transmitter, wherein at least one of the receivers has a first variable gain at the front stage. means (10), a first amplitude limiting circuit (3) having a second variable gain means (11) at a subsequent stage; at least one said transmitter comprises a first amplitude limiting circuit (3) having a third variable gain means (12) at a preceding stage; a second amplitude limiting circuit (6) having a control means (13) in which the first, second and third variable gain circuits are limited in response to a received signal or by remote control;
) A satellite repeater characterized by comprising: (2) The satellite repeater according to claim (1), wherein the variable gain means is a variable attenuator.