JPH05336524A - Satellite communication television transmission system - Google Patents

Abstract

PURPOSE:To provide the satellite communication television transmission system which reduces beatlike interference between adjacent channels when plural television signals are transmitted by sharing a communication satellite. CONSTITUTION:For the transfer of plural television signals by the communication satellite, a specified reference ground station is equipped with a reference signal generating circuit 1 and a transmitter 2 for the transmission of a reference television signal and respective transmitting ground stations have a receiver 7 which restores the reference television signal and a transmitter 6 which supplies the restored reference television signal to a GEN lock function or TV camera 3 and a VTR 4 having clock synchronizing inputs and sends a video signal.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a satellite communication television transmission system, and more particularly to frequency division of one or more satellite repeaters mounted on a communication satellite to transmit a plurality of television signals transmitted from an earth station. The present invention relates to a relay transmission method.

[0002]

2. Description of the Related Art Conventionally, in this type of satellite communication television transmission system, one or a plurality of satellite repeaters of a communication satellite are frequency-divided into N channels as shown in FIG. A plurality of television signals to be transmitted. The television signals from this earth station individually transmit TV signals, and the signals are transmitted asynchronously with each other. In addition, the frequency band assigned to each earth station is made as narrow as possible by, for example, the # 3 channel in FIG. The program is being transmitted. In this case, it is usual to use 100% utilization within the occupied bandwidth for transmission.

[0003]

Since this conventional satellite communication television transmission system performs transmission under the severe conditions as described above, when the attenuation characteristic of the band limiting filter in the transmitting / receiving earth station is poor, the transmission from the adjacent channel is started. In particular, in the case of transmitting a television signal, there is a drawback that the line frequencies of both channels are different and beat components due to asynchronism appear as a loop in a received image. .

[0004]

In the satellite communication television transmission system of the present invention, in the satellite communication television transmission system for transmitting a plurality of television signals from the earth station by the communication satellite, the designated reference earth station is A reference television signal generation circuit and a transmitter are provided, and each transmitting earth station has a receiver for restoring the reference television signal and a GEN lock function or a clock synchronization signal input for the restored reference television signal. A transmitter for supplying the reference signal input to the television signal generating device and transmitting the output signal of the television signal generating device.

[0005]

The present invention will be described below with reference to the drawings. FIG. 1 shows a block diagram (a) of a reference earth station and a block diagram (b) of each transmitting earth station according to an embodiment of the present invention. First, a reference earth station designated from among earth stations that perform television transmission by jointly using communication satellites has a reference television signal generation circuit 1 with high time accuracy, and outputs this output signal to a transmitter 2. After that, it always transmits to other earth stations via communication satellites. As the reference signal, a composite television signal, a black burst signal, or a vertical synchronizing blanking signal can be used in the case of analog FM transmission, and a clock synchronizing signal is used in the case of digital transmission. For each of the multiple transmitting earth stations,
The receiver 7 shown in (b) receives and restores the reference signal from the reference earth station, and the television camera 3 and VTR 4
Supply to GEN lock input of TV camera 3 or VTR
The signal is transmitted to the satellite repeater at the transmitter 6 via the video switcher 5 for signal switching. This reference signal is supplied as a clock synchronization signal to the video encoder in the case of digital transmission. On the other hand, in one or more satellite repeaters of communication satellites, as shown in FIG.
If the transmission channel of the reference earth station is the #N channel, both the reference signal program and the program N-1 are relayed. Also, although each earth station is relayed by TV using the channels # 1 to # N-1, all are synchronized with the reference signal program, so that the obstacle causing the beat interference can be eliminated.

[0006]

As described above, according to the present invention, the frequency array on the communication satellite is divided into narrow bands, and in the worst case, all the programs that are used in common in television transmission even if they interfere with other channels. Since the common reference signal is used for synchronization, the line frequencies of the program between adjacent channels are also synchronized, so that beat interference does not occur and interference fringes do not occur in the received image.

[Brief description of drawings]

FIG. 1 is a configuration diagram (a) and (b) of a reference earth station and a transmitting earth station according to an embodiment of the present invention, respectively.

FIG. 2 is a channel frequency allocation diagram of the satellite repeater of the present embodiment.

FIG. 3 is a channel frequency allocation diagram of a conventional satellite repeater.

[Explanation of symbols]

 1 Reference Signal Generation Circuit 2, 6 Transmitter 3 Television Camera 4 Video Tape Recorder (VTR) 5 Video Switch 7 Receiver

Claims (1)

[Claims] 1. In a satellite communication television transmission system for transmitting a plurality of television signals from an earth station by a communication satellite, a designated reference earth station includes a reference television signal generating circuit and a transmitter, The transmitting earth station receives the receiver for restoring the reference television signal and the restored reference television signal by G
A satellite provided with a transmitter for supplying a reference input signal of a television signal generating device having an EN lock function or a clock synchronization signal input and transmitting an output signal of the television signal generating device. Communication television transmission system.