JPH04196638A - Satellite communication system - Google Patents

Abstract

PURPOSE:To simplify the circuit scale and to prevent production of a block error by correcting an error based on majority decision in response to the quality state of a transmission line. CONSTITUTION:A transmission terminal station equipment uses a synthesis section 12 to synthesize a transmission information signal T from a ground transmission line and repetitive number (n) information K designated in response to the quality of a transmission line to form a synthesis information signal TA. Then a modulation section 16 modulates the transmission data signal TB by a transmission clock E to send the result to a satellite transmission channel as a transmission signal TC in which each bit of the transmission information signal T is repeated by n-times. Then a majority decision section 24 of a reception terminal station equipment applies majority decision to the n-bit data and outputs the result of discrimination as a majority decision output signal RE. Thus, the circuit scale is simplified and a block error due to consecutive correction mistake is eliminated.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a satellite communication system, and more particularly to a satellite communication system that guarantees the communication quality of digital signals against deterioration of transmission path conditions due to rain attenuation and the like.

[Conventional technology]

2. Description of the Related Art Conventionally, as a means for ensuring the communication quality of digital signals in satellite communications, there has been an error correction method using Viterbi or the like. FIG. 2 is a diagram showing an example of a conventional satellite communication system, and shows a transmitting terminal device and a receiving terminal device of an earth station that transmits information signals via a communication satellite. The transmitting terminal device includes an encoding section 31, a transmission speed converting section 32, an oscillating section 33,
The receiving terminal device includes a modulation section 34, and a demodulation section 41.
, a reception speed conversion section 42 and an error correction section 43.

The transmitting end station device receives the information signal T from the terrestrial transmission line and the terrestrial transmission lock A, and the encoder 31 performs encoding processing for error correction to generate an encoded information signal T1 and an encoded clock B. Output. In addition, the transmission speed conversion section 32 allows the oscillation section 3 to be faster than the terrestrial transmission lock A.
The signal is converted into a data signal T2 synchronized with the transmission clock I from No. 3, and further modulated by the transmission clock I by the modulation section 34, and sent to the satellite transmission path as a transmission data signal T3.

In the receiving end station device, a demodulating section 41 demodulates the received data signal R1 received via the satellite transmission path and outputs the data signal R2 and the receiving clock J, and a receiving speed converting section 42
The encoded received data signal R3 is converted into an encoded received data signal R3 synchronized with the decoding clock D from the error correction unit 43 and outputted, and the encoded received data signal R3, which has been speed-converted, is further error-corrected by the error correction unit 43 and transmitted on the ground. The information signal R is decoded into an information signal R synchronized with the lock C and sent to the terrestrial transmission line.

[Problem to be solved by the invention]

In the conventional satellite communication system described above, in order to perform error correction, encoding and decoding are performed based on the mutual relationship of each bit of information signal data, which not only makes the circuit configuration complicated and increases the circuit scale. If a correction error occurs in a state where the satellite transmission path is significantly degraded, continuous correction errors occur and block errors occur.

An object of the present invention is to simplify the circuit scale by enabling error correction by majority decision according to the quality state of the transmission path without performing encoding and decoding processing for error correction. Another object of the present invention is to provide a satellite communication system in which block errors do not occur due to continuous correction errors as in the prior art.

[Means to solve the problem]

The satellite communication system of the present invention includes means for generating and transmitting a transmission signal in which each bit of an information signal is repeated by a number of repetitions set according to the quality state of a transmission path, and a means for generating and transmitting a signal indicating the number of repetitions. means for detecting the number of repetitions by receiving a signal including information on the number of repetitions sent from the sending side; The receiving side is provided with means for reproducing the information signal by making a majority decision for each bit repetition number. Further, the configuration may be such that the transmitting side includes means for combining the signal indicating the number of repetitions with the transmission signal and transmitting the signal, or the signal indicating the number of repetitions is transmitted using a line different from that for the transmission signal. The configuration may be such that the transmitting side is provided with a means for doing so.

〔Example〕

Next, the present invention will be explained with reference to the drawings.

FIG. 1 is a diagram showing an embodiment of the present invention, and shows a transmitting end station device and a receiving end station device of an earth station. The transmitting terminal device includes a repetition number setting section 11, a combining section 12, a transmission speed converting section 13, an oscillating section 14, a transmitting frequency dividing section 15, and a modulating section 1.
6, and the reception terminal device also includes a demodulation section 21, a serial-parallel conversion section 22, a latch section 23, a majority decision section 24, a repetition number detection section 25, a reception frequency division section 26, and a reception speed conversion section 27. We are prepared.

Next, the operation will be explained.

The transmitting terminal device receives the transmission information signal T from the terrestrial transmission path, the terrestrial transmission lock A, and the repetition number information K designated according to the quality state of the transmission path, and sets the repetition number information K to the repetition number setting section 11. At the same time, the combining section 12 combines the transmission information signal T and the repetition number information to form a combined information signal T^. Now, the number of repetitions n (n is a positive integer)
is set in the repetition rate setting unit 11, the transmission frequency division unit 15 receives the transmission clock E from the oscillation unit 14, which is at least n times faster than the terrestrial transmission lock A, and divides it into 1
/n and outputs the divided clock F. The transmission speed converter 13 receives the composite information signal T^, the terrestrial transmission lock A, the transmission clock E, and the divided clock F, and outputs the repetition number information part of the composite information signal TA in synchronization with the transmission clock E. , by outputting the transmission information signal portion of the composite information signal TA in synchronization with the divided clock F,
The speed of the composite information signal TA is converted to obtain the transmission data signal Ts. The modulator 16 modulates the transmission data signal TB using the transmission clock E and sends it to the satellite transmission path as a transmission signal Tc. By the way, in the modulation section 16, by modulating the transmission information signal part synchronized with 1/n of the transmission clock E with the transmission clock E, a signal in which each bit of the transmission information signal is repeated once is obtained. Output. Further, since the repetition number information part is synchronized with the transmission clock E, it is output as is.

In the receiving end station device, a demodulator 21 demodulates the received signal R^ received via the satellite transmission path, and outputs the received data signal RB and the received clock L. The repetition number detection unit 25 is
The receiver detects the number of repetitions n of the received data signal R, which includes repetition number information, generates, holds, and outputs a signal G indicating the number of repetitions n. The reception frequency divider 26 receives the signal G indicating the number of repetitions n and the reception clock L, divides the signal into 1/n, and outputs the divided clock H. The serial-parallel converter 22 is composed of a shift register circuit, converts the received data signal Ra from the demodulator 21 into a parallel signal Rc, and outputs the parallel signal Rc. The latch unit 23 latches n-bit data of the parallel signal RC in accordance with the frequency divided clock H and sends a latch output signal RD to the majority decision unit 24. The majority decision section 24 receives the latch output signal Ro and the signal G indicating the number of repetitions n, makes a majority decision on n-bit data, and outputs the decision result as a majority decision output signal RE.

The reception speed converter 27 receives the majority decision output signal RE.

It receives the frequency divided clock H and the terrestrial transmission lock C, outputs a majority decision output signal RE synchronized with the terrestrial transmission lock C, and sends it out as a reception information signal R to the terrestrial transmission line.

As can be seen from the above operation, as the number of repetitions n increases, the number of bits of the latch output signal Rn increases, and the data error rate decreases due to majority decision.

In addition, the quality of the satellite transmission path is monitored by monitoring signals from communication satellites, and the number of repetitions n is determined depending on the quality of the satellite transmission path.
By setting , error correction can be performed by majority decision according to the quality of the satellite transmission path.

In this embodiment, the repetition number information is combined with the transmission information signal as a means of transmitting it to the other station, but the repetition number information is transmitted to the other station using a line different from the transmission information signal. can be implemented in the same way.

〔Effect of the invention〕

As explained above, according to the present invention, the transmitting side repeatedly transmits each bit of the information signal according to the quality state of the transmission path, and also transmits a signal indicating the number of repetitions, while the receiving side Detects the number of repetitions by receiving an information signal in which each bit is repeated from the transmitting side and a signal indicating the number of repetitions,
Since the information signal is reproduced by making a majority decision on each bit of the received information signal for each number of repetitions, it not only simplifies the circuit scale, but also eliminates block errors caused by continuous correction mistakes that occur during encoding and decoding processing. disappears.

Furthermore, since a signal indicating the number of repetitions is transmitted to the other station, the other station can recognize the number of repetitions of the incoming information signal, and each station can independently set the number of repetitions when transmitting to the other station. This eliminates the need for a monitoring station to control each station that joins the network, simplifying network operation.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing an embodiment of the present invention, and FIG. 2 is a diagram showing an example of a conventional satellite communication system. 11... Repetition number setting unit, 12... Combining unit, 13°32... Transmission speed converting unit, 14.33... Oscillating unit,
15... Transmission frequency divider, 16. '34 --- Modulation section, 2
1゜41...-Demodulation section, 22... Serial-parallel conversion section, 23... Latch section, 24... Majority decision section, 25... Repetition number detection section, 26... Reception frequency division Department,
27.42...Receiving speed converter, 28..., 31...
... Encoding unit, 43... Error correction unit, T... Transmission information signal, R... Reception information signal, Tc... - Transmission signal,
RA...-received signal, K...repetition number information, n...
Number of repetitions.

Claims (1)

[Claims] 1. Means for generating and transmitting a transmission signal in which each bit of an information signal is repeated by a repetition number set according to the quality state of a transmission path, and generating and transmitting a signal indicating the repetition number. means for detecting the number of repetitions by receiving a signal indicating the number of repetitions sent from the sending side; and means for receiving the transmission signal sent from the sending side and detecting each bit. A satellite communication system characterized in that a receiving side is provided with means for reproducing the information signal by making a majority decision for each of the number of repetitions. 2. The satellite communication system according to claim 1, further comprising means on the transmitting side for combining the signal indicating the number of repetitions with the transmission signal and transmitting the signal. 3. The satellite communication system according to claim 1, further comprising means on the transmitting side for transmitting the signal indicating the number of repetitions using a line different from that for the transmission signal.