JPH0837486A - Mobile body communication system - Google Patents

Abstract

PURPOSE:To enable signal transmission even when a signal is interrupted by installing a 1st delay means delaying an original signal by a prescribed time at a transmission station, a means demodulating the original signal and a 2nd delay means delaying the signal by the same time as that of the 1st delay time at a mobile station. CONSTITUTION:When a reception electric field fault takes place in a, time slot (-1, (D), 1) equivalent to a time slot 2 of a signal 116, a demultiplexer 10 receives a signal 109 and demultiplexes the faulty slot into the signals 110, 111. The signal 110 is a forward part of the time slot being the synthesized signal 109 and a backward part of the signal 111. The signal 111 not delayed is given to a delay device 11 and the signal is delayed by the same time as the delay time at the delay device 2 to be a signal 112. A signal 113 is a synchronization discrimination signal of a demodulator 9 to detect a time slot of the signal 109 to be in error and an asynchronous detection signal is outputted after one time slot. A signal 114 is selected by a changeover device 12 according to a level of the signal 113 and not failed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to wireless communication, and more particularly to a mobile communication system for transmitting data such as TV signal transmission from a transmitting station to a mobile station.

[0002]

2. Description of the Related Art A conventional mobile communication system will be described below with reference to FIG. In the configuration shown in the figure, on the transmission side, a video signal 101, which is an output signal of the TV camera 1, is modulated by a modulator 4 and then converted to a radio frequency by a transmission high-frequency unit 5 and provided to a transmission antenna 6. The radio signal 106 output from the transmitting antenna 6 is received by the receiving antenna 7 and
After being amplified by, the signal is demodulated by the demodulator 9 through the frequency conversion processing and becomes the video signal 109.

In mobile communication such as reception by a receiving device mounted on a vehicle, when there is an obstacle such as a tree or a building, a shadow wing phenomenon in which radio waves are greatly attenuated occurs (hereinafter, shadow wing). A line break occurs. In this case, there is a problem that the demodulated image is disturbed because the correct video signal cannot be obtained on the receiving side. As a means for solving the disturbance of the received image due to the shadow wing, there is a method of repairing information loss by using a resending means which is carried out in normal data transmission. Had the drawback of losing. Therefore, conventionally, during the line disconnection, the storage unit 1 uses the out-of-sync signal output from the synchronization determination signal 113.
4 is controlled to switch to the immediately preceding video signal 115 stored in the storage unit 14 in advance, thereby preventing image disturbance. Further, when there is no shadow wing, the switch 12 outputs the determination signal 113 as a normal synchronization signal and switches the switch 12 so that the output signal of the demodulator 9 becomes the output signal 114 as it is.

The above prior art is disclosed in, for example,
No. 5081.

[0005]

In the conventional method, it is possible to prevent the disorder of the restored image, but since it was not possible to prevent the loss of information at the time of a momentary disconnection of the line due to shadow wings, etc. Was becoming. It is an object of the present invention to provide a transmission method that does not cause loss of information even if a circuit group is generated.

[0006]

A mobile communication system according to the present invention is a mobile communication system in which a signal (original signal) is transmitted from a transmitting station to a mobile station via a wireless line. First delay means for delaying the original signal by a predetermined delay time, and the signal delayed by the first delay means within a predetermined time and the original signal do not overlap at the same time as the predetermined time. And a receiving unit that receives the signal transmitted from the transmitting station to the mobile station, and a combining unit that transmits the output signal of the combining unit. Demodulation means for demodulating the combined signal of the combining means from the received signal, separation means for separating the output of the demodulation means into the signal delayed by the first delay means and the original signal, and the separation means. The converted original signal with the first delay means A second delay means for delaying by one hour and a signal delayed by the first delay means when the received signal is normal, and the original signal when the received signal is abnormal. And switching means for switching to select the signal delayed by.

[0007]

Embodiments of the present invention will be described with reference to the drawings. FIG. 1 shows a first embodiment of the present invention at the time of live TV broadcasting. The video signal 101 (original signal) output from the TV camera 1 is converted into a digital signal by the A / D converter 20 and then delayed for a predetermined time by the delay unit 2 to obtain a delayed signal 102. In the synthesizer 3, the output signal 116 of the A / D converter 20 is output.
And the delay signal 102 are synthesized. After the signal 103 synthesized by the synthesizer 3 is modulated by the modulator, the signal 103 is converted into a radio frequency by the transmission high frequency unit and supplied to the transmission antenna 6. The radio signal 106 output from the transmission antenna 6 is received by the reception antenna 7 of the reception station, amplified by the reception high frequency unit 9, frequency-converted, demodulated by the demodulator 9 and separated by the separator 10.
The signal is divided into a signal 111 input to the delay unit 11 and a signal 110 input directly to the switch 12. Demodulated signal 1 separated
11 is delayed by the same time as the transmission side by a delay unit 11 and input to the switch 12 together with the output signal of the separator 110.
The switch 12 outputs a synchronization determination signal 11 output from the demodulator 9.
3 when the demodulated signal is synchronized, the output signal 1
10 is selected, and the delay unit 112
Output signal 112 is selected. The output signal of the switch outputs the received video signal 114, and the analog video signal (original signal) is restored by the D / A converter 21.

FIG. 2 shows the temporal changes in the signal waveform of each part of the present invention.

In the figure, reference numeral 116 is an A / D converter 20.
, And the time slots 2, 3, and 4 are provided for each time slot at an equal interval T (sec).

Reference numeral 102 denotes an output signal 1 of the A / D converter 20.
16 is delayed by the delay device 2 by 2T (sec). 1
03 denotes an output signal of the synthesizer 3 and the signal 102 is 2
A signal processed at twice the speed and a signal processed at twice the speed of the signal of the A / D converter 20 are synthesized.
As a result, the signal 103 includes, for example, the time slot 0 and the time slot 2 in the time slot 3 of the signal 116.
Are synthesized at T / 2 (sec).
In the case of time slot 2 of signal 116 and time slot 0 (D) of signal 103, for example,
(D), 2).

Reference numeral 109 denotes an output signal of the demodulator on the receiving side. In this figure, the delay time in the wireless transmission path is omitted for simplification.

Here, for example, it is assumed that the reception electric field failure occurs in the time slot (-1 (D), 1) corresponding to the time slot 2 of the signal 116 due to the shadow of the reception electric field.

The separator 10 receives the signal 109 and outputs the time slot (−1 (D), 1) in which the failure has occurred to the signal 11.
0 and signal 111 are separated.

Here, the signal 110 is on the front side (delayed signal) of the combined time slot of the signal 109,
The signal 111 is after the time slot of the signal 109 (a signal that is not delayed).

The undelayed signal 111 is delayed by the same amount of time as it is input to the delay device 11 and delayed by the delay device 2 (two time slots in this example) to become a signal 112.

A signal 113 is a synchronization determination signal of the demodulator 9 and is a time slot (−1) of the signal 109 in which a failure has occurred.
(D), 1), and outputs an asynchronous detection signal after one time slot.

A signal 114 is an output signal of the switch 12. When the output of the signal 113 is at a low level, the signal 110 is selected.
When the signal 110 is at the high level, the signal 110 is selected, and when the output of the signal 113 to be asynchronous is at the high level, the signal 112 is selected. As a result, as the signal 114, a signal which is not affected at all is continuously obtained.

In the present embodiment, the delay units 2 and 11 are, for example,
Since a digital delay circuit using a D flip-flop that is normally used can be used, it is easily configured.

In the above embodiment, the case where the video signal is converted into a digital signal and digitally processed is described. However, when the original signal is a digital data signal, it need not be converted into a digital signal.

FIG. 3 shows a second embodiment of the present invention, which has a data generator 31 and a data receiver 32 and an A / D.
The configuration is the same as that of FIG. 1 except that the converter 20 and the D / D converter 21 are not provided. That is, in this example, the delay processing is performed on the digital signal as it is.

Further, the signal waveform of each part of this embodiment is the same as that of the time slot of FIG.

[0022]

As described above, according to the present system, signal transmission can be performed without loss of information even when a momentary interruption occurs in the transmission line due to shadowing or the like. In this embodiment, the TV relay is described as an example, but it is clear that the present invention is effective for all systems that transmit data in real time.

[Brief description of drawings]

FIG. 1 is a block diagram of a first embodiment of the present invention.

FIG. 2 is a timing chart of the first embodiment of the present invention.

FIG. 3 is a block diagram of a second embodiment of the present invention.

FIG. 4 is a block diagram of a conventional example.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 TV camera 2 Delay device 3 Synthesizer 4 Modulator 5 Transmission high frequency part 6 Transmission antenna 7 Transmission antenna 8 Reception high frequency part 9 Demodulator 10 Separator 11 Delay device 12 Switcher 13 TV receiver 14 Storage device 20 A / D conversion Device 21 D / A converter 31 Data generator 32 Data receiver

Claims (4)

[Claims] 1. A mobile communication system for transmitting a signal from a transmitting station to a mobile station via a (original signal) wireless line, wherein the transmitting station delays the original signal by a predetermined delay time. An output signal of the synthesizing means; a synthesizing means for synthesizing the signal delayed by the first delay means within a predetermined time and the original signal so as not to overlap at the same time as the predetermined time. Receiving means for receiving the signal transmitted from the transmitting station to the mobile station, and demodulating means for demodulating the combined signal of the combining means from the received signal obtained by the receiving means. Separating means for separating the output of the demodulating means into the signal delayed by the first delay means and the original signal, and the original signal separated by the separating means at the same time as the first delay means. Second delaying means for delaying only Switching means for switching the signal delayed by the first delay means when the received signal is normal, and selecting the signal delayed by the second delay means for the original signal when the received signal is abnormal A mobile communication system comprising: 2. The control device according to claim 1, wherein the switching unit controls the demodulation unit by outputting a determination signal for determining that the received signal is synchronized when the received signal is synchronized and outputting an abnormal signal when the received signal is asynchronous. The mobile communication system according to claim 1, wherein 3. The mobile communication system according to claim 1, wherein said synthesizing means temporally compresses the first delayed signal and the original signal by processing at a high speed. 4. The mobile station according to claim 1, wherein the transmitting station includes analog-to-digital conversion means when the original signal is an analog signal, and the mobile station includes digital-to-analog conversion means. Body communication system.