JPS63185234A - Transmission/reception system for satellite broadcast - Google Patents

Abstract

PURPOSE:To adjust the phase of a TV signal at a ground station, by detecting a phase difference between a reference frame synchronizing signal in a satellite and the frame synchronizing signal of a television video signal sent from a ground transmission station, and sending it to the ground transmission station. CONSTITUTION:A broadcasting satellite 100 detects the phase difference between an i-th number of TV signal and a reference frame signal at a switch matrix 4, and sends it to an i-th number of zone via an antenna 8i. The ground transmission station 90 of the i-th number of zone, after receiving it with a reception antenna 91, demodulates a phase difference detecting signal with a receiver 92, and impresses it on the transmitter 93 of the TV signal. Thus, the TV signal outputted from the transmitter 93 is delayed by a delay time designated by the phase difference signal and is outputted. In such a way, in a stationary state, the phases of all of the TV signals are synchronized with the reference frame synchronizing signal, and the phase of the TV signal can be kept as it is even when it is switched by the switch matrix 4.

Description

[Detailed Description of the Invention] Technical Field The present invention relates to a satellite broadcasting transmission/reception system, and in particular has a function of switching each TV (television video) signal received by an on-board multi-beam antenna in phase synchronization with each other by a switch matrix. This relates to the transmission and reception method of multi-beam broadcasting satellites.

Conventional technology Direct satellite broadcasting using high-power transmission has the advantage of making receiving equipment more economical, and by converting the broadcasting area into multiple beams, it is possible to reuse frequencies, improve the efficiency of satellite power, and organize programs by region. It is possible to introduce

In view of this, a so-called multi-beam broadcasting satellite system has been proposed. In this system, a multi-beam antenna is mounted on a satellite, each having multiple irradiation areas as transmitting and receiving areas, and by combining frequencies, polarization methods, etc. multiple T
A V signal wave is obtained and each of these TV signal waves is amplified and relayed by a plurality of transponders provided correspondingly.

Furthermore, in order to increase the flexibility of broadcast programs across regions and zones, a configuration is adopted in which switch matrices are installed between each of the plurality of transponders so that signal paths can be selectively switched at will. In this case, the switching timing of the switch matrix is determined by instructions from the ground control station, but simply switching the route of each TV signal using the switching instruction command signal will result in discontinuous synchronization of the TV signals sent from the broadcasting satellite. Therefore, there is a drawback that the satellite broadcast receiving apparatus becomes out of synchronization and the image quality deteriorates.

Therefore, it is necessary to completely synchronize and control the switching of TV signals of a plurality of channels in a switch matrix, and for this purpose, it is necessary to synchronize frames with each other at the switching contact positions of the switch matrix. In order to match the frame synchronization with each other, there is a circuit that detects the phase of the frame synchronization signal of each TV signal, and a circuit that adjusts the TV signal phase to compensate for the phase difference between the frame synchronization signals detected by this detection. A variable delay circuit is required.

However, since these circuits, especially variable delay circuits, use the most human-sized memory circuits, they are disadvantageous in terms of unit size, power consumption, etc. when used as satellite-borne equipment. . Therefore, a method is conceivable in which these frame synchronization phase detection circuits, variable delay circuits, etc. are installed at the terrestrial transmitting station.

Purpose of the Invention The present invention has been made in view of such demands, and its purpose is to
It is an object of the present invention to provide a transmission and reception system for multi-beam satellite broadcasting that can be controlled at a ground transmitting station so that the frame synchronization phases of signal waves are perfectly matched.

Structure of the Invention The satellite broadcasting transmission system according to the present invention detects the phase difference between the reference frame synchronization signal in the satellite and the frame synchronization signal of the television video signal transmitted from the ground transmitting station, and transmits this detected information to the ground. It is characterized in that it is transmitted to a transmitting station.

The satellite broadcasting transmission and reception system according to the present invention detects the phase difference between a reference frame synchronization signal in the satellite and a frame synchronization signal of a television video signal sent from a ground transmitting station, and transmits this detected information to the ground transmitting station. The ground transmitting station receives this detection information, controls the frame synchronization signal phase of the television video signal of its own station according to the detection information, and transmits the signal.

Example Hereinafter, the present invention will be explained in detail using the drawings.

FIG. 1 is a block diagram of a broadcasting satellite used in an embodiment of the present invention. Receiving antenna 11 corresponding to r irradiation areas
Each TV signal received by ~1r is divided by splitter 2 into n
The signal is divided into n signals and supplied to n receivers 31 to 3, respectively. Each of these receivers performs signal processing such as amplification, frequency conversion, demodulation, and decoding in accordance with the signal modulation method, and then inputs the signal to n frame synchronization phase detection circuits 31 to 3, respectively.

Each of these frame synchronization phase detection circuits detects the phase difference between the reference frame synchronization signal generated from the reference frame synchronization signal generator 50 and the frame synchronization signal included in each input TV signal. The detected phase difference information is input to the transmitters 61 to 6, respectively, and each input TV signal that has passed through the frame synchronization phase detection circuits 51 to 5n is sent to the transmitters via the switch matrix circuit 4. 61 to 6n.

This switch matrix circuit 4 has n T
It is assumed that a switch network is configured that can selectively connect each of the V signals to any one of the n transmitters 61 to 6.

Each of the n transmitters 61 to 6n performs necessary signal processing such as encoding, modulation/two-frequency conversion, amplification, etc. on the output signal switched and selected by the switch matrix 4. It is also assumed that similar signal processing is performed on the phase difference detection information of the frame synchronization signal. The outputs of the respective transmitters are combined by the splitter 7 for each transmission irradiation area, and are transmitted from the respective transmitting antennas 81 and 8t. The switch control circuit 5 controls the switch matrix 4 based on the connection correspondence table signal and the switching command signal from the ground control station.

The reference frame synchronization signal generator 50 generates a reference frame synchronization signal for the TV signal from a stable and highly accurate oscillator, and supplies it to n frame synchronization phase detection circuits 51 to 5n. In these frame synchronization phase detection circuits, Fig. 2 (a
) From each input TV signal waveform shown in FIG. 2(b), a synchronization signal portion exceeding the pedestal level is extracted, and a synchronization signal is generated for each frame in which odd and even fields are detected. The phase difference t with respect to the reference frame synchronization signal shown in FIG. 2(C) is detected.

In addition, in FIG. 2(C), T indicates the period of the reference frame.

The thus detected phase difference information is output in the form of an analog voltage or digital quantity, and this information is signal-processed by each of the n transmitters 61 to 6n and then sent out.

FIG. 3 is a schematic block diagram showing the relationship with the broadcast W1 star for explaining the operation of the terrestrial transmitting station. Here, the broadcasting satellite 100 detects the phase difference between the first TV signal and the reference frame signal at the switch matrix 4, and transmits the first phase difference signal 16i (in this example, in combination with the TV signal transmitter). ) is modulated and amplified, and then transmitted through the antenna 81 toward the i-th zone.

The terrestrial transmitting station 90 in the i-th zone receives this signal with a receiving antenna 91, demodulates the phase difference detection signal with a receiver 92, and applies it to a TV signal transmitter 93. This transmitter 9
Reference numeral 3 includes a variable delay circuit (not shown) that can arbitrarily set the delay time of the TV signal over one frame or more. A variable delay circuit can be realized using a digital memory that can control the phase difference between writing and reading over one frame or more, but if the TV signal is an analog signal, A-D
(analog-digital) conversion circuit and A (digital-to-analog) conversion circuit may be added.

In this way, the TV signal output from the transmitter 93 is delayed by the delay time indicated by the phase difference signal and sent out. This transmission signal is transmitted from the transmitting antenna 94 toward the broadcasting satellite 100 and reaches the receiving antenna 11 of the satellite. This TV signal reaches the switch matrix 4 through the duplexer, receiver, etc. in the satellite 100, as described above. In this way, the broadcasting satellite 100 receives n TV signals from n zones, and the switch matrix 4
supplied to

With the above configuration, in the steady state, all the TV signals are synchronized in phase with the reference frame synchronization signal, and the switch matrix 4
Even if the signals are switched, the phases of the TV signals before and after switching are continuous.

In the present invention, several modifications can be made in addition to the embodiments described above. For example, the reference frame synchronization signal may be generated by the switch control unit 5 in the satellite, or it may be generated on behalf of any terrestrial transmitting station and become the reference signal when it reaches the satellite. It can also be defined as

Further, the phase difference detection signal between each TV signal and the reference frame synchronization signal may be transmitted to the ground via n phase difference signal transmitters provided for each zone, respectively.
Further, it can also be used in common with the transmitters 61 to 6n provided for each zone as shown in the above embodiment. Furthermore, it is also possible to multiplex the phase difference signals and transmit them using one transmitter and antenna provided for the global beam.

Effects of the Invention As described above, according to the present invention, each terrestrial transmitting station can adjust the phase of the TV signal to be transmitted using the phase difference information of each TV signal transmitted from the satellite. It is sufficient to install hardware such as a variable delay circuit at the upper station, and the effect is that there is no need to install such hardware on the broadcasting satellite. Therefore, in the switch matrix inside the satellite, switching is controlled at a timing when the frame synchronization phase always matches between the TV signals to be switched, and no synchronization loss will occur in the satellite broadcast receiver. Become.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of a broadcasting satellite according to an embodiment of the present invention, and FIG.
This figure is an operation time chart of the frame synchronization phase detection circuit shown in FIG. 1, and FIG. 3 is a system block diagram of a transmission/reception system according to an embodiment of the present invention. Explanation of symbols of main parts 4...Switch matrix 5...Switch control circuit 50...Reference frame synchronization signal generators 51-5
n...Frame synchronization phase detection circuit 90...
...Ground transmitting station 100...Broadcasting satellite

Claims (2)

[Claims] (1) The phase difference between the reference frame synchronization signal in the satellite and the frame synchronization signal of the television video signal sent from the ground transmission station is detected and this detected information is sent to the ground transmission station. Characteristic satellite broadcasting transmission method. (2) Detect the phase difference between the reference frame synchronization signal in the satellite and the frame synchronization signal of the television video signal sent from the ground transmitting station, and send this detection information to the ground transmitting station. 1. A satellite broadcasting transmitting/receiving system characterized by receiving lever detection information and controlling and transmitting a frame synchronization signal phase of a television video signal of its own station according to the detection information.