JPS609382B2 - Multi-beam satellite onboard relay device - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a satellite-mounted repeater used in a digital satellite communication system, and is particularly effective for a multi-beam satellite communication system that relays and amplifies burst signals of multiple carrier waves. This relates to a relay device.

Conventionally, the communication method most commonly used in satellite communication systems has been the FDM-FM-FDMA method.

However, in order to cope with the increase in the number of earth stations participating in the system and the increase in communication demand, consideration is being given to introducing digital satellite communication systems that have higher efficiency, larger capacity, and can flexibly follow traffic fluctuations. One of these is Satellites, which combines multi-beam satellites and TOMA technology, and is equipped with a dynamic switch on the satellite to switch beam connections at high speed in synchronization with the TDMA frame.
A method called Mtched TDMA (SS/TDMA) has already been put into practical use. Figure 1 shows SS/TDMA
Among the systems, an example of the configuration of a satellite repeater in the SS/TDMA system using multiple carrier waves, which has been proposed especially for small stations with a small amount of communication, is shown.

In the figure, RB, RB2, R& are the receiving beam elements of the satellite.
B, is for A, B, C stations, RB2 is for D, E, F stations, R&
is an example of accommodating one station of G and one day. Each earth station also has f. , et al., f3 are assigned. 2 is the receiver,
3 is a demultiplexer that is provided for each receiving beam and separates each received signal into frequencies f, , f2, and f3; 4 is a demodulator; Baseband signal times.

A baseband switch matrix that rearranges the baseband signal for each transmitting beam element, TB, T string, T& by exchanging the bits; 6 is a modulator provided corresponding to the transmitting beam element; TB, TB2, T&; is the receiving beam RB,,
Like R& and RB3, this is a transmission beam element accommodating stations A to 1. FIG. 2 is a diagram showing the operating procedure of this system, particularly the time slots assigned to each earth station.

The TDMA frame length T (usually set in the range of 2 to 3 hs) is divided into sections 7, 72, T3, and in section 7, the earth station accommodated in the receiving beam element RB, In section 2, the earth station housed in RB2 is in section 7.
3 is used by the earth station housed in RB3. Furthermore, in each section 73, each earth station uses each transmit beam element TB in each section.
,, The time slot of each earth station is determined so that the signals sent to TB2 and TB3 do not overlap on the time axis. The baseband switch matrix 5 collects signals for each transmission beam element TB, TB2, and TB3 and operates to generate a TDMA signal that is continuous on the time axis. Although the conventional technology has been described above, the following drawbacks can be pointed out regarding the conventional configuration.

'1} As is clear from FIG. 1, when the number of reception beams is 1, the number of frequencies is m, and the number of transmission beams is n, the baseband switch matrix 5 has (1×m) input pairs n
output, making the configuration complex. '2As is clear from Fig. 2, the operating rate of each demodulator 4 is 1' in the example of Fig. 2.
3, and 1×m demodulators are required, resulting in a lot of wasted power consumption. The present invention has been made in order to solve the above-mentioned conventional drawbacks, and provides a multi-beam satellite onboard relay device that reduces active circuits, saves power and improves reliability, and has a simple configuration. The purpose is to provide.

The present invention will be explained in detail below.

FIG. 3 shows an embodiment in which the present invention is applied to a system that replaces time slots in the baseband band similarly to FIG. 1.

In the figure, 7 is a synthesizer, and other symbols indicate the same parts as in the conventional example of FIG. 1, respectively. In this embodiment, before demodulating the received signal, signals of the same frequency are synthesized in advance by a synthesizer 7, and then demodulated. As is clear from FIG. 2, the received signals can be combined simply by power combining since time slots of the same frequency do not overlap on the time axis. According to the present invention, as is clear from the comparison between FIGS. 1 and 3, the baseband switch matrix 5
is simplified from a configuration of (1×m) inputs to n outputs to a configuration of m inputs to n outputs, the number of demodulators 4 is also reduced from (1×m) to m, and each demodulator In principle, the operation rate of the device 4 is approximately 100% when operated according to the procedure shown in FIG. In addition, since the synthesizer 7 can be configured with passive elements, high reliability can be achieved as a whole, and furthermore, power saving can be achieved. In addition, when power is combined by the combiner 7 in FIG. 3, a signal is input from one of the three inputs of the combiner 7, and noise is input from the other two inputs. There is a possibility that the signal-to-noise ratio of the signal at the output of 7 may deteriorate. In such a case, an amplitude limiter 8 may be provided between the demultiplexer 3 and the combiner 7, as shown in FIG. This amplitude limiter 8 can be constructed of a diode or the like having characteristics approximately as shown in FIG. 5, and the provision of this amplitude limiter has almost no effect on the effects of the present invention. Next, a case will be described in which the present invention is applied to a satellite-mounted repeater that switches time slots of signals in the microwave band.

First, a conventional example is shown in FIG.

In the figure, 9 is a frequency converter that converts the received frequencies f, , f3 to a predetermined frequency (').
cy/Convener), 10 is a microwave band switch matrix that switches the time slots of the IF signal, 11 is a transmitter that converts the IF signal to a predetermined transmission frequency, and sends out the signal with a predetermined power; Reference numerals indicate the same parts as those in FIGS. 1, 3, and 4, respectively. FIG. 7 shows an embodiment in which the present invention is applied to this conventional example.

In this embodiment as well, signals of the same frequency are synthesized in advance by the synthesizer 7, and then the frequency is converted by the frequency converter 9. As is clear from the comparison between FIG. 6 and FIG. By simplifying the switch matrix 10, reducing the number of frequency converters 9, and improving the operating rate, the same effects as the embodiment shown in FIG. 3 can be achieved. In this embodiment as well, in order to prevent signal quality deterioration during power combination by the combiner 7, an amplitude limiter 8 is installed between the demultiplexer 3 and the combiner 7, as in the embodiment shown in FIG. All you have to do is set it up. In the above embodiments of the present invention, the receiving beam is two beams, the number of earth stations accommodated in each beam is three earth stations, and the frequency used is three waves.
The implementation of the present invention is not limited to these numbers.

In addition, in the embodiment, a system that only exchanges time slots between received signals is taken as an example, but in the embodiments shown in FIGS. 3 and 4, in place of the baseband switch matrix 5, the received signal The present invention can also be applied to a system provided with a signal processing circuit that performs signal speed conversion processing and multiplexing processing. As described above, according to the present invention,
It is possible to realize a satellite-mounted relay device that has a simple configuration, high efficiency, high reliability, and low power consumption, and its effects are very large.

[Brief explanation of drawings]

1 and 6 are block diagrams showing conventional examples, FIG. 2 is a time chart for explaining the operation of the example in FIG. 1, and FIG.
4 and 7 are block diagrams showing embodiments of the present invention, and FIG. 5 is a characteristic diagram of the amplitude limiter according to the embodiment of FIG. 4. RB,,RB2,R&... Receive beam element, T
B,, TB2, TB3... Transmission beam element, 2...
receiver, 3. ．． …． Demultiplexer, 4... Demodulator, 5
...Baseband switch matrix, 6.
...Modulator, 7...Synthesizer, 8...
Amplitude limiter, 9... Frequency converter, 10... Microwave switch matrix, 11... Transmitter. Tsutomu 1 drawing Tsutomu 2 drawings High 3 drawings Multi 4 drawings Akira 5 drawings Poor 6 drawings Multi 7 drawings

Claims (1)

[Claims] 1. A plurality of receivers provided corresponding to a plurality of receiving beams, a plurality of branching filters that separate and output each output signal of the plurality of receivers by carrier frequency, and each of the plurality of branching filters. In a multi-beam satellite on-board relay device comprising at least a plurality of signal conversion means for individually converting output signals into signals of desired frequency bands, between the plurality of demultiplexers and the plurality of signal conversion means. A plurality of combiners are provided, and after each output signal of the plurality of demultiplexers is combined for each carrier frequency by a corresponding one of the plurality of combiners, the signal is converted into a desired frequency band by the plurality of signal conversion means. A relay device for use on a multi-beam satellite, which is characterized by converting signals into signals.