JPS6294046A - Digital transmission equipment - Google Patents

Abstract

PURPOSE:To prevent malfunction at the reception side by changing a part of voice signal forcibly when the voice signal at the sending side is coincident with a transmission signaling consecutively for a prescribed number of times or over. CONSTITUTION:A comparator circuit 7 compares the content of a shift register 3 with that of a shift register 11. When the contents of the registers 3, 11 are coincident consecutively, a coincidence signal is sent from the circuit 7 and a counter 15 counts the signal. When the counter 15 counts the coincidence signal for a prescribed number of times, the output of the counter 15 goes to logical 1 and its output signal is inputted to an EX OR gate 17. The gate 17 inverts the least significant bit LSB of the register 11. In this case, the digitized voice signal outputted via a P/S converting circuit 5 and the OR gate 19 is converted into a signal different from an off-pattern signal of the transmission signaling. Thus, the malfunction at the reception side is prevented.

Description

[Detailed Description of the Invention] [Technical Field of the Invention] The present invention relates to a digital transmission bag d that converts audio signals and signaling signals into digital signals and transmits them, and in particular, the present invention relates to a digital transmission bag d that converts audio signals and signaling signals into digital signals and transmits them. This paper relates to the adoption of an in-band transmission method for signaling signals that are transmitted over the network.

[Technical Background of the Invention] Conventionally, there is a transmission system as shown in FIG. 3, in which audio signals and signaling signals are converted into digital signals and transmitted and received using the same digital signal line. As shown in the figure, the transmission signaling signal (S
After the S signal) and the audio signal are respectively digitized and converted into a digital SS signal and a digital audio signal,
The signals are multiplexed onto the same line and output as digital output signals.

To explain this transmission system in more detail, the digitization of the SS signal is performed only for the off-signal of the SS signal, and the digital SS signal is obtained only when the SS signal is off. Since the SS signal is in the OFF state until a call is made, this OFF signal is digitized and sent out as a digital output signal (FIG. 3(C)). When a call is made, the SS signal turns on, and along with this, the digital SS
No signal will be sent. Next, when the caller dials, a dial pulse signal is sent from the SS signal, which is digitally converted into a -C digital SS signal and output as a digital output signal.

When the receiving side receives the dial pulse signal, it calls the called party using a bell, etc. When the called party answers, the audio signal line is connected, and when the calling party makes a call, the audio signal is digitized and digital voice is generated. It is converted into a signal and output as a digital output signal.

(Problems with the Background Art) However, in such a digital transmission system, if the digitized audio signal matches the digitized SS signal, a malfunction occurs on the receiving side, and for example, in the above case, the SS signal is considered to be off. There were problems such as the line being disconnected.

[Purpose of the invention]

SUMMARY OF THE INVENTION An object of the present invention is to provide a digital transmission device capable of supplementing the digital audio signal even if it coincidentally coincides with the digital SS (No. 8) in order to solve the above-mentioned problems.

[Summary of the invention]

In order to achieve the above object, the present invention provides a digital transmission device that digitizes and transmits audio signals and signaling signals, compares the digitized audio signal and the jig touring signal, and as a result of the comparison, the digitized The present invention is characterized by comprising means for forcibly changing a part of the digitized audio signal related to the matching when the number of matches between the digitized audio signal and the signaling signal reaches a predetermined value.

[Embodiments of the invention]

Examples of the present invention will be described in detail below. FIG. 1 is a circuit diagram of the transmitting side according to this embodiment, in which the audio signal is digitized by a pulse code modulation (PCM) conversion circuit 1 and becomes a 3-bit parallel signal.
Parallel-to-serial conversion circuit (P/S
(conversion circuit) 5 and comparison circuit 7.

The off signal generator 9 outputs the A of the transmission signaling (SS) signal.
An 8-bit parallel signal indicating a pattern is generated, and this signal passes through a 3-bit shift register 11.
The signal is input to the comparison circuit 7 and the parallel-to-serial conversion circuit (P/S conversion circuit) 13.

Comparison circuit 7 compares the contents of shift register 3 and shift register 11. If the contents of both match, it sends a match signal to counter 15, and if they do not match, it clears counter 15.

The counter 15 counts the coincidence signals, and when the count of the coincidence signals reaches a predetermined value, its output becomes 1'.

The output of the counter 15 and the output of the least significant bit (LSB) of the shift register 11 are input to an exclusive OR (EX OR) gate 17, and the output of this EX OR gate 17 is input to the least significant bit (LSB) of the shift register 3. is input.

The P/S transformation circuit 13 receives the SS signal, and when the SS signal is off, it converts the contents of the shift register 13 into a serial signal and sends it to the OR gate 19. When the SS signal is on, it does not send out the signal. .

The OR gate 19 receives the digital audio signal converted into a serial signal by the P/S conversion circuit 5 and the off signal of the SS signal converted into a serial signal by the P/S conversion circuit 13.

Next, the operation on the transmitting side will be explained. PCM conversion circuit 1
The digitized audio signal passes through the shift register 3, is converted into a serial signal by the P/S conversion circuit 5, and is input to one OR gate. On the other hand, the off pattern signal generated by the off signal generator 9 is passed through the shift register 11, converted to a serial signal by the P/S conversion circuit 13, and inputted to the OR gate 19.
is output as a digitized output signal.

The output signals of the shift register 3 and shift register 11 are input to a comparison circuit 7. Comparison circuit 7 compares the contents of shift register 3 and shift register 11, and if they match, sends a match signal to counter 15, and if the contents of both registers do not match, clears counter 15. When the contents of shift register 3 and shift register 11 match consecutively, a match signal is sent from comparator circuit 7, and counter 1
5 counts this coincidence signal. When the counter 15 counts a predetermined number of matching signals, the output of the counter 15 is 1'
This output signal is input to the EX OR gate 17. When one input of the EX OR gate 17 is 1', its output is the inverted version of the other input signal, so when the output of the counter 15 is 1', the output of the EX OR gate 17 is the highest output of the shift register 11. The least significant bit LSB of the shift register 3 is rewritten by this inverted signal.

That is, when the contents of shift register 3 and shift register 11 match for a predetermined number of consecutive times, the least significant bit LSB of shift register 3 is inverted.

At this time, the digitized audio signal outputted via the P/S conversion circuit 5 and one OR gate is converted into a signal different from the off pattern signal of the SS signal.

FIG. 2 is a circuit diagram showing a schematic configuration of the receiving side.

The received digital signal is input to an inverse PCM conversion circuit 21, a coincidence circuit 23, and a mismatch circuit 25. Reverse PCM
A conversion circuit 21 generates an audio signal from the received digital signal.A matching circuit 23 compares the off pattern of the signaling signal with the received digital signal.
・If there is an off pattern in this digital signal, a signal is output to the counter 27. Counter 27 is matching circuit 2
When the number of signals output from the circuit 3 is counted by a predetermined number, a signal is sent to the latch 29.

The mismatch circuit 25G compares the received digital signal and the A pattern of the signaling signal, and sends a signal to the counter 31 if they do not match. counter 3
1 counts the output signal of the mismatch circuit 25 and sends a signal to the latch 29 when the count reaches a predetermined number of times. The latch 29 outputs a reception signaling (SR) signal that turns off when a signal is input from the counter 27 and turns on when a signal is input from the counter 31.

When an off-pattern signal indicating that the original SS signal is turned off is input from the transmitting side, a matching signal is output from the matching circuit 23, and the counter 27 receives this signal as a count value exceeding the set value. Then, the output of the latch 29 is turned off, and the off state of the SS signal is transmitted to the receiving side. Further, when a signal different from the oats pattern signal is input, the mismatch circuit 25 operates, and when the count value of the counter 31 exceeds a set value, the latch 29 outputs an on signal.

Note that since it is the least significant bit LSB of the audio signal that is forcibly changed on the transmitting side, there is no problem of audio signal deterioration.

Furthermore, in this embodiment, an example in which audio signals are digitized using the PCM method is taken up, but it goes without saying that the present invention can also be applied to digitization using other methods such as the AI') PCM method. It is.

〔Effect of the invention〕

As explained in detail above, according to the present invention, if the audio signal matches the SS signal consecutively for a predetermined number of times or more on the transmitting side, a part of the audio signal is strongly changed and sent to the receiving side. Therefore, even if the Fuse signal coincides with a predetermined SS signal by chance, this will not cause a malfunction on the receiving side.

[Brief explanation of drawings]

Figure 1 shows the transmission (7 side circuit diagram, 2nd side circuit diagram) of the digital transmission equipment.
The figure is a circuit diagram of the receiving side, and FIG. 3 is a time chart of transmission signaling signals and audio signals. 1...l] CM conversion circuit, 3.11... Jit register, 5.13... P/S conversion circuit, 7... Comparison circuit, 9... Off pattern signal generator, 15・・・Counter, 17...[×OR gate, 21...Reverse P C
M conversion circuit, 23... Match circuit, 25... Mismatch circuit, 27.31... Counter, 29... Wrap-0
Figure 1

Claims (1)

[Claims] In a digital transmission device that digitizes and transmits an audio signal and a signaling signal, the digitized audio signal and the signaling signal are compared, and as a result of the comparison, the number of matches between the digitized audio signal and the signaling signal is determined. A digital transmission device comprising means for forcibly changing a part of the digitized audio signal related to the coincidence when a predetermined value is reached.