JPH0783345B2 - Signal transmission method - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a signal transmission system for synthesizing and transmitting an information signal together with a digital voice signal, and in particular, the digital voice signal is adaptive digital modulation (hereinafter referred to as ADM). ) Related to the signal transmission method encoded by the method.

(Prior Art) A conventional signal transmission system is configured as shown in FIG. 4, for example. In FIG. 4, 1 is a microphone and 2 is
ADM encoder, 3 synthesis circuit, 4 transmitter, 5 transmission press switch, 6 operation unit, 7 ST / information signal generation circuit, 8 receiver, 9 delay circuit, 10 ADM decoder , 11 is a switch, 12 is a speaker, 13 is a start pattern detection circuit, 14 is an information signal reading circuit, 15 is a display, 16 is a timer, 17 is a squelch signal detection circuit, and 18 is an AND gate.

In FIG. 4, the transmitting side 100 includes a microphone 1, an ADM encoder 2, a synthesizing circuit 3, a transmitter 4, a transmitting press switch 5, an operating section 6, and an ST / information signal generating circuit 7. It stands.

On the other hand, the receiving side 200 has a receiver 8, a delay circuit 9 and an ADM.
Decoder 10, switch 11, speaker 12, start pattern detection circuit 13, information signal reading circuit 14, and indicator
15, a timer 16, a squelch signal detection circuit 17, and an AND gate 18.

In FIG. 4, the transmitting side 100 operates as follows.

That is, the audio signal input from the microphone 1 is
It is converted into a digital voice signal by the ADM encoder 2.
On the other hand, the information signal is obtained as follows. In the operation unit 6, the data input by the key is generated as information. In the ST / information signal generation circuit 7, not only the start pattern but also the information signal pattern is selected according to the information input from the operation unit 6. Since the memory is used for the ST / information signal generating circuit 7, the state of the transmission press switch 5 is detected and output. That is, when the transmission press switch 5 notifies the end of the call, the ST / information signal generating circuit 7 outputs a start pattern and an information signal.

This signal pattern is an NRZ signal. The same explanation can be applied to the system that outputs the start pattern and the information signal at the beginning of the summer. In the synthesis circuit 3,
The output of the ST / information signal generating circuit 7 and the output of the ADM encoder 2 are combined and sent to the transmitter 4. When the transmission press switch 5 is pushed down, the transmitter 4 transmits the output of the synthesis circuit 3.

The format of the transmitted signal is configured as shown in FIG. 5, and the start pattern and the information signal are transmitted at the end of the digital voice signal.

Next, the receiving side 200 operates as follows.

That is, the output of the receiver 8 passes through the delay circuit 9 and is decoded by the ADM decoder 10 into an analog voice signal. Switch 11 is set to off when receiver 8 is not receiving,
During reception, the start pattern and the information signal are also set to OFF when being output from the delay circuit 9 to prevent the speaker 12 from outputting as voice. The squelch signal detection circuit 17 determines whether or not the receiver 8 is in the reception state. When not receiving, "0" is output from the squelch signal detection circuit 17. Whether or not the start pattern and the information signal are being received is determined by the start pattern detection circuit 13 and the timer 16. When the start pattern is detected by the start pattern detection circuit, the timer 16 operates for a certain period of time. The output is held at “0”. When either the squelch signal detection circuit 17 or the timer 16 is in the state of "0", that is, it is judged that it is not receiving, or is a non-voice signal even during receiving, the AND gate 18 outputs To “0”
Then turn off the switch 11.

The information signal is processed as follows. When the start pattern detection circuit 13 determines that the start pattern is detected, the information signal output from the receiver 8 is read by the information signal reading circuit 14. The contents of the information signal reading circuit 14 are displayed on the display unit 15, and the operation unit 6 of the transmitting side 100 is displayed.
The key pressed by is revealed.

(Problems to be Solved by the Invention) As described above, in the conventional signal transmission method, when the information signal is transmitted together with the digital voice signal, the start pattern is not detected under the condition that the bit error rate is high. The pattern matching is performed so that even if there is some error, it can be tolerated.

Therefore, since it cannot be easily identified whether it is a digital voice signal or an information signal, the receiving side erroneously determines the voice signal as an information signal and closes the voice path, or vice versa. Therefore, there is a drawback that it may output an unpleasant sound and generate an unpleasant sound.

When the error tolerance is low in the detection of the start pattern, the probability that the start pattern cannot be detected (non-detection rate) increases due to a bit error in the transmission path. When the start pattern is not detected, the switch 11 is on. At this time, the start pattern decoded by the ADM decoder 10 and the information signal are output from the speaker 12 through the switch 11. In particular, when the NRZ signal is an information signal, there is a drawback in that a humming sound or a buzzing sound can be heard as a very loud sound, which is very annoying.

On the other hand, if the error tolerance is increased in the detection of the start pattern, the probability that the digital audio signal will be mistaken for the start pattern and detected will increase (error detection rate). There is a drawback that there is a risk of being destroyed.

The object of the present invention is to transmit an information signal by using a binary pulse phase modulation method when the information signal is synthesized and transmitted in a signal transmission system for converting a voice signal into a digital voice signal by the ADM system and transmitting the digital voice signal. By doing so, it is an object of the present invention to provide a signal transmission system configured to eliminate the above-mentioned drawbacks and to reliably detect a start pattern.

(Means for Solving Problems) A signal transmission system according to the present invention comprises a transmitting side and a receiving side for converting a voice signal into a digital voice signal by an adaptive digital system and transmitting the digital voice signal.

The transmitting side transmits an information signal different from the digital voice signal at the start or end of the transmission of the digital voice signal.
It is provided with a phase modulator for phase-modulating a pulse signal according to the Manchester code of the value.

On the other hand, the receiving side is equipped with a phase demodulator for demodulating a phase modulated wave by a pulse signal.

(Example) Next, this invention is demonstrated with reference to drawings.

FIG. 1 is a block diagram showing an embodiment for realizing the signal transmission system according to the present invention. In FIG. 1, 1
Is a microphone, 2 is an ADM encoder, 3 is a synthesis circuit, 4 is a transmitter, 5 is a transmission press switch, 6 is an operating unit, and 7 is
ST / information signal generation circuit, 8 is a receiver, 9 is a delay circuit, 10
Is an ADM decoder, 11 is a switch, 12 is a speaker, 13 is a start pattern detection circuit, 14 is an information signal reading circuit, 15 is an indicator, 16 is a timer, 17 is a squelch signal detection circuit, and 18 is
An AND gate, 19 is a phase demodulator, and 20 is a phase modulator.

The transmitting side 100 includes a microphone 1, an ADM encoder 2, a synthesizing circuit 3, a transmitter 4, a transmitting press switch 5, an operating unit 6, an ST / information signal generating circuit 7, and a phase modulator 20. Consists of.

The receiving side 200 includes a receiver 8, a delay circuit 9, and an ADM decoder 10.
A switch 11, a speaker 12, a start pattern detection circuit 13, an information signal reading circuit 14, a display 15, a timer 16, a squelch signal detection circuit 17, and an AND gate 18.
And a phase demodulator 19.

On the transmitting side 100, the difference from FIG. 4 of FIG. 1 is that the start pattern and the information signal output from the ST information signal generating circuit 7 are directly the NRZ signal, and the combining circuit 3
The point is that they are not synthesized by the above, but are synthesized after being modulated by the phase modulator 20. Assuming that the 1-bit time of the output of the ADM encoder 2 is T, the 1-bit time of the output of the ST / information signal generating circuit 7 is 2nT (n = 1,2,3 ...) Time at the output of the phase modulator 20. Is supported. That is, the output pattern of the ST / information signal generating circuit 7 is either 1010 ... 10 or 0101 ... 01 at the time of 2nT.

FIG. 2 is a timing chart showing an actual example of the information signal when n = 1. In this case, the waveform shows a rising edge corresponding to “1” of the information signal and a falling edge corresponding to “0” of the information signal at the center point in the 2T section. Transmission using such a waveform is called Manchester code. In the present invention, the Manchester code has the highest information signal transmission efficiency.

On the receiving side, what is different from FIG. 4 in FIG. 1 is a phase demodulator 19 for obtaining an information signal. Phase demodulator 19
Performs a reverse operation unlike the phase modulator 20, and generates and outputs an NRZ signal by exchanging from an input waveform represented by a time unit of 2nT. ADM decoder at receiver 200
The output of 10 behaves in a completely different manner to the start pattern and the information signal. The ADM decoder 10
An analog signal is obtained by theoretically integrating the input digital signal.

Explaining the spectrum, the NRZ signal has energy concentrated in the low frequency component. However, in the binary phase modulation method in which 1 bit is expressed by 2nT as shown in the present invention, the low frequency component There is little energy. In particular, the energy of the low frequency component decreases as the value of n increases.

From the properties of the spectrum described above, the following can be said.

Since the ADM decoder 10 extracts the energy of the low frequency component of the input digital signal by the integration characteristic, when the NRZ signal is used for the start pattern and the information signal as shown in FIG. Similarly, it outputs a waveform with a large amplitude. On the other hand, when transmitting the start pattern and the information signal by the binary phase modulation method as in the present invention, the amplitude of the output of the ADM decoder 10 is small. In particular, the larger n is, the smaller the amplitude is. Therefore, in the present invention, due to the influence of noise on the transmission line, etc.
Even when the start pattern in 200 cannot be detected, the output level of the ADM decoder 10 is small, so that hearing the information signal as a sound does not cause annoyance. This means that depending on the system, the error tolerance can be lowered by detecting the start pattern. That is,
There are multiple receivers 200 for the same sender 100,
It is assumed that some of them do not require the function of receiving the information signal. In such a system, there is no practical problem even if the detection rate of the start pattern is low.

According to the present invention, even when the information signal sound is output from the speaker, the volume is low, so that there is no annoyance. The fact that the error tolerance can be lowered in the detection of the start pattern means that the rate of falsely detecting the start pattern by error can be made extremely smaller than that of the digital voice signal. Actually, the phenomenon of instantaneous interruption of the voice signal is stochastically ignored. To be done.

In particular, in a system in which the signal quality during silence does not have to be taken into consideration, there is no practical problem even if the delay circuit 9 and the timer 16 are omitted. In particular, when the value of n is large as the phase modulation method, the output level of the ADM decoder 10 becomes very small, so the delay circuit 9 and the timer 16 are unnecessary.

(Effect of the invention) As described above, the present invention transmits an information signal by a phase modulation method that hardly contains low frequency components,
In the coding method that extracts the low frequency component using the integration characteristic like the ADM decoder, it is said that even if the sound recording signal is output from the speaker on the receiving side, the level is low and there is no annoyance. There is.

Also, depending on the system, some receivers do not need to receive the information signal, and in this case, the probability that the voice signal will be interrupted because it is not necessary to lower the error tolerance of the start pattern more than necessary. Has the effect that it is practically ignored.

[Brief description of drawings]

FIG. 1 is a block diagram showing an embodiment for realizing the signal transmission system according to the present invention. FIG. 2 is a timing diagram showing an example of an information signal adopted in the signal transmission system according to the present invention. FIG. 3 is a timing diagram showing an example of a signal transmission method that does not employ phase modulation / demodulation. FIG. 4 is a block diagram showing an example of realizing a signal transmission system according to the related art. FIG. 5 is an explanatory diagram showing an example of a signal format composed of a digital voice signal and an information signal. 1 ... Microphone, 2 ... ADM encoder 3 ... Synthesis circuit, 4 ... Transmitter 5,11 ... Switch 6 ... Operating section 7 ... ST / information signal generation circuit 8 ... Receiver 9 ... Delay circuit, 10 …… ADM decoder 12 …… Speaker 13 …… Start pattern detection circuit 14 …… Information signal reading circuit 15 …… Display, 16 …… Timer 17 …… Squelch signal detection circuit 18 …… AND gate 19 ...... Phase demodulator, 20 …… Phase modulator 100 …… Sending side, 200 …… Reception side

Claims (1)

[Claims] 1. A signal transmission system comprising a transmitting side and a receiving side for converting a voice signal into a digital voice signal by an adaptive digital system and transmitting the digital voice signal, wherein the transmitting side starts transmission of the digital voice signal. At the end of transmission or at the end of transmission, a phase modulator for phase-modulating an information signal different from the digital audio signal into a pulse signal of a binary Manchester code is provided, and the receiving side demodulates a phase modulation wave of the pulse signal. A signal transmission system characterized by being configured with a phase demodulator for performing.