JPS5840862B2 - Synchronous signal transmission method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a synchronization signal transmission system that can accurately transmit synchronization signals.

When PSK is used as a synchronization signal, if temporal discontinuity or phase shift occurs in the middle of the line, a single synchronization malfunction will occur.

For example, if the same radio wave is received at two or more locations,
In the case of a system in which the signal is collected centrally through a line and the signal with the best S/N is selected and switched, if there is a difference in the amount of delay between the receiving location and the center, an apparent phase change may occur when switching. , resulting in synchronization malfunction.

The present invention eliminates this drawback by adding a pseudo synchronization signal in addition to the regular synchronization signal in a time-division manner, and conversely detecting the regular synchronization signal by verifying the time series of the signal on the receiving side. This is what I did.

Examples thereof will be described below.

In FIG. 1, 11 is a signal source that generates a regular synchronization signal, 12 is a signal source that generates a pseudo synchronization signal, and 13 is the second one.
a signal source that generates a signal for selectively controlling two synchronization signals; 1;
Numeral 4 is a multiplex that selectively combines two synchronization signals using its control signal, and 15 is a PSK modulator.

16 is a PSK demodulator, 18 is a timing signal generation circuit, and 17 is a synchronization signal verification circuit.

11 to 15 constitute a transmitter, and 16 to 17 constitute a receiver.

Next, the operation will be explained.

The synchronization signal source 11 generates the original synchronization signal shown in FIG. 2A, and the synchronization signal source 12 generates the pseudo synchronization signal shown in FIG.

These two synchronization signals are selected by a control signal of the signal source 13 (shown in FIG. 2C).

When the control signal is at H level, a regular synchronization signal is selected, and when it is at L level, a pseudo synchronization signal is selected by multiplex 14, and a composite signal shown in FIG. 2B is created.

This composite signal is modulated by the PSK modulator 15 and sent to the transmission path.

On the receiver side, the transmitted signal is demodulated by a PSK demodulator 16, and if a phase change occurs in the received signal, a test circuit 1T tests the phase change before and after the phase change.

That is, now, let us assume that the verification time width is ±t2 based on the output of the generation circuit 18, and the pseudo phase change width is 11, so that t2>
Set it to 2tl.

In this case, the `l'H'' section of the control signal shown in FIG. 2C is made larger than t2.

In this way, the verification circuit 17 is configured to ``if there is no change in the amount of ±t2 before and after the phase change, it is regarded as a regular synchronization signal and a pulse is generated at the desired time.''

This way, even if a line change occurs in the pseudo synchronization section and a phase change occurs as shown in Figure 2, or if one pseudo phase change is missing as shown in Figure 2, malfunctions will not occur. Must not be.

- Of course, when a line change occurs during a regular synchronization interval, the regular synchronization signal will not be detected, but if the above composite signal is sent repeatedly in time, synchronization will be detected again after synchronization is achieved. All you have to do is let it run on its own.

Note that FIG. 2H shows an example of line changes in a conventional transmission system, where a malfunction occurs at the arrow.

Figure 3 shows the specific configuration of the verification circuit 17 in Figure 1, which verifies whether or not there is a phase change before and after ±t2 when there is a phase change in the input signal. Generates output at times.

First, the input signal a is delayed using the shift register 21 for a time slightly longer than t2.

With this delayed output, when an exclusive OR is performed on the input signal a at the gate 22, a pulse c is generated when both phases are different.

That is, by verifying whether the pulse width of this pulse C is greater than or equal to t2, it is possible to verify whether there is no phase change within ±12 hours.

The output d of the decoder 23 generates a pulse at time t2 after the rise of the pulse, and this sets the R-8 flip-flop 24.

If the pulse width of the pulse C is 12 or more, a signal d is generated, the output e becomes 11'', the reset function of the vinyl counter 25 is stopped through the gate 26, and the output g is generated through the decoder 27 at the desired time. Reset the flip-flop 24 and return to the original state.

Further, if the pulse width of pulse C is less than t2, the counter 25 is immediately reset.

Therefore, no output is generated with a pseudo synchronous signal, but an output is generated with a regular synchronous signal.

Further, FIG. 4 shows signal waveforms of main parts of FIG. 3, and corresponding parts are given the same symbols a to g.

As is clear from the above embodiments, according to the present invention, a signal obtained by time-divisionally adding a regular synchronization signal and a pseudo synchronization signal is sent from the transmitting side, and the receiving side detects the temporal change in the signal and synchronizes. Since the signal is detected, the synchronization signal can be detected accurately even if there is a phase change in the transmission path.

[Brief explanation of drawings]

Fig. 1 is a block diagram of an embodiment embodying the synchronization signal transmission method of the present invention, Fig. 2 is a signal waveform diagram thereof, Fig. 3 is a block diagram showing the detailed configuration of the main part, and Fig. 4 is its signal waveform diagram. It is a signal waveform diagram. 11... Synchronous signal source, 12... Pseudo synchronous signal source, 14... Multiplex, 17.
... Verification circuit.

Claims (1)

[Claims] 1. Sends a composite sync signal that is obtained by time-divisionally adding a regular sync signal and a pseudo sync signal, and performs an exclusive OR of the delayed composite sync signal obtained by delaying the received composite sync signal and the composite sync signal to generate a pulse signal. A synchronization signal transmission system characterized in that a regular synchronization signal is detected by determining whether the pulse width of this pulse signal is equal to or greater than a predetermined value.