JPS5946141B2 - Synchronous signal transmission method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a synchronization signal transmission method used when transmitting two audio signals simultaneously over a line for one audio channel by using, for example, audio pause time. The purpose is to do so.

FIG. 5 schematically shows a transmission system for simultaneously transmitting two audio signals over a line for one audio channel by using audio pause time.

As shown in FIG. 5, this audio transmission system compresses audio, synthesizes it, and transmits it via a one-channel line. On the receiving side, the transmitted signal is divided and each is expanded to restore the audio. That is, the level of one sector of the audio waveform a shown in A of FIG. 6 is detected, and when the level is greater than a certain value as shown at the beginning of FIG. As shown, sectors with a level value of 1 are cut out. Next, these signals are arranged every other sector as shown in FIG. 6-2. In this case, the pause information represents the pause length by the number of sectors and is incorporated into one sector. In the same way, the signal shown in Fig. 6 (e) and the signal shown in (2) obtained from the voice are combined to create the signal shown in Fig. 6 (b), and the signal is transmitted over a 1-channel line. On the receiving side, the frame signal is divided into sectors based on the frame signal, and divided into every other sector, and the audio sector is extracted from the audio sector a (sixth picture 1). 6th
The signals shown in Figure 6 are sequentially arranged with a pause signal inserted as shown in Figure 6H. The audio a shown in FIG. 6 is restored from the signal in FIG. The present invention relates to, for example, a synchronization signal transmission system for frame detection in such transmission.

An embodiment of the present invention will be explained below with reference to the drawings.

Reference numeral 1 denotes a bandpass amplifier that floods the input signal applied to the input terminal, 2 a delay circuit using a semiconductor delay element whose delay time can be varied by the clock frequency, 3 and 4 a delay circuit 2, and a bandpass amplifier 1. This is a zero-cross circuit that converts the output of each into a rectangular wave.

5 is an exclusive OR circuit which takes the exclusive OR of the output waveforms of zero cross circuits 3 and 4.

6 is a low frequency wave generator, and 7 is a comparator circuit.

8 is a pulse width switch that detects only a pulse signal of a desired pulse width.

9 is a frequency dividing circuit having a reset terminal, and 11 is a synchronizing signal output terminal.

Next, the operation of each part based on this configuration will be explained with reference to the waveform diagram shown in FIG.

In the case of a BS. When the K (phase shift key ink) wave enters, most of the noise or audio signal leakage is removed by the bandpass filter 1, resulting in the waveform shown at the beginning of FIG. This signal is then separately applied to the delay circuit 2 and zero cross circuit 4. Letting the frequency of the PSK wave be Fs, the output signal of the bandpass filter 1 is transmitted by the delay circuit 2 to τ=n
/Fs (n is a positive integer). This waveform is shown in FIG. 2C. The waveform signals shown in FIG. 2 (C) and 2 (E) are applied to the respective zero cross circuits 3 and 4, and the waveforms are converted into binary signals as shown in FIG. 2 (2) and (E). This circuit ensures that synchronization detection is not affected even if the amplitude of the PSK wave applied to the input terminal 10 fluctuates. The respective binary signals shown in FIG. This waveform is shown in FIG. By this circuit 5, the delay time τ of the delay circuit 2 from the synchronization sending point (change of phase) is 1.
If the signal is left as it is, a whisker-like waveform may appear due to the deviation of the elements as shown in Fig. 2. This is removed by the low-frequency wave generator 6. The waveform is shown in Fig. 2. This signal is again converted into a binary signal with a pulse width τSec by the comparator circuit 7. This waveform is shown in Fig. 2 (h). Fig. 2 (l) shows the time axis of This is a condensed drawing, and when the 42-value signal in Figure 2-H is taken as τ8e0, it shows a state where τ1 is smaller than τ800 or τ2 is larger than τ800 due to noise, voice leakage, etc. Output of comparator circuit 7 The pulse width switch circuit 8, which receives as input, is formed of a one-shot multi-channel circuit or a counter, and is configured to detect only pulses of .DELTA..tau.
Therefore, in the case of τ1 or τ2, no output is produced as shown by the waveform in FIG. 4 show waveforms at various parts when noise or audio signal leakage is too large to be removed by the bandgap converter 1.

In FIG. 4A, part A is the noise that could not be removed. In this case, the pulse width (τ1) of the pulse shown in FIG.
τ), it is not detected by the pulse width detection switch 8. FIG. 7 shows a case where the pulse width of the output of the comparator circuit 7 is larger than τ. 7th
When noise is added to the signal at the timing shown in A in the figure, the rise timing of the exclusive OR circuit 5 changes, and the pulse width τ2 of the output of the comparator circuit 7 becomes larger than τ. Note that A in FIG. 7 shows the P.I.
S. K waveform, the output waveform of the band wave generator 1, C the output waveform of the delay circuit 2, 2 and E the output waveforms of the zero cross circuits 3 and 4, and the output waveform of the exclusive OR circuit 5.
5 shows the output waveform of the comparator circuit 7. Note that FIG. 3 shows a state in which the pulse width switch 8 of FIG.

Therefore, when the pulse width of the waveform shown in FIG. 2C is disturbed due to noise or voice leakage, that signal will not be detected, and only the synchronization signal that is considered to be approximately accurate will be detected.

This waveform is shown in FIG. This signal is applied to the reset terminal of the frequency dividing circuit 9, and a synchronizing signal is output from the output terminal 11. The waveform of this synchronization signal is shown in Figure 2. As explained above with reference to the embodiments, according to the present invention, by using a semiconductor delay element for differential detection and appropriately determining the clock frequency, the pulse width of the detected output can be arbitrarily set as shown in FIG. Moreover, since a pulse width switch circuit is added, the signal that reaches the frequency dividing circuit is only a fairly accurate signal.

This signal also resets the frequency divider circuit, which is normally free-running, and outputs a synchronizing signal to the output terminal. For this reason, if it is necessary to send a synchronization signal to the audio signal and overlay to the radio, etc., the audio signal may be mixed in or the radio may be overlayed with a synchronization signal. D.
Because of the C characteristic, even if the synchronization signal is clipped by an audio signal, the synchronization signal generated at the output terminal is hardly disturbed. Furthermore, even if the S/N ratio sometimes becomes extremely poor as in radio equipment, the synchronization signal obtained when the S/N ratio was good can be maintained.

[Brief Description of the Drawings] Fig. 1 is a block diagram of an embodiment of the synchronous signal transmission system according to the present invention, Fig. 2 is a signal waveform diagram of each part of the configuration shown in Fig. 1, and Fig. 3 is a diagram of the signal waveforms of each part of the configuration shown in Fig. 1. Some specific configuration diagrams, FIG. 4 is a signal waveform diagram of each part when noise or audio signal leakage is large in the configuration shown in FIG. 1, and FIG. FIG. 6 is an explanatory diagram of the operation of the audio transmission method, and FIG. 7 is a signal waveform diagram of each part when noise is superimposed in the configuration shown in FIG. 1. 2... Delay circuit, 3, 4... Zero cross circuit, 5... Exclusive OR circuit,
8... Pulse width switch circuit, 9...
Frequency divider circuit.

Claims (1)

[Claims] 1. Receive a PSK (phase shift key ink) wave transmitted from a transmitting means, delay the received PSK wave, and then convert it into a first rectangular wave, and convert the received PSK into a second rectangular wave.
The first and second rectangular waves are added to an exclusive OR circuit, the pulse width of the pulse output from this exclusive OR circuit is detected, and this pulse width is determined to be a predetermined pulse width. A synchronous signal transmission method characterized by correcting the self-running of a free-running synchronous signal generation system only when the system is running. 2. The synchronization signal transmission system according to claim 1, wherein the received PSK wave is converted into a rectangular wave by a zero-cross circuit.