JPH08163059A - Fault diagnostic device for single channel coding circuit - Google Patents

Abstract

PURPOSE: To obtain a fault diagnostic circuit for a single channel coding circuit in which a fault of the coding circuit is detected even when a channel is busy. CONSTITUTION: A transmitter side analog signal and a test signal outputted from a test signal generating section 7 are added by an adder 4 and the sum signal is converted into a digital signal at an A/D converter 6 and a test signal component is extracted from the digitally converted signal by a BPF 11. Furthermore, the test signal is converted into a digital signal at an A/D converter 9. The test signal component and the digitally converted test signal are compared by a test signal detection section 12, and when they are dissident, it is diagnosed that the A/D converter 6 failed. Moreover, a test signal erasure section 13 erases the test signal from the sum signal between the digitally converted transmitter side analog signal and the test signal.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fault diagnosis apparatus for a single channel coding circuit, and more particularly to a fault diagnosis apparatus for a single channel coding circuit when a channel is used.

[0002]

2. Description of the Related Art In early PCM terminal equipment, a coding / decoding circuit (CODEC) was expensive, so that a common CODEC for coding / decoding after multiplexing a plurality of speech paths was used.
Was often used. In the common CODEC, a monitoring signal (pilot signal) is inserted into an unused communication path among a plurality of communication paths to be accommodated, and the failure of the common CODEC is detected by detecting the monitoring signal.

On the other hand, in the current PCM terminal equipment, codes
Since the decoding circuit (CODEC) has been downsized and inexpensive, a single channel CODEC that performs encoding and decoding for each single channel has been widely used. In addition, in the case of a single communication channel CODEC, since encoding and decoding are performed by the CODEC for each communication channel, the influence of a failure is limited to the corresponding communication channel, there is no influence on other communication channels, and the monitoring circuit is not used. Single communication path CODEC
In general, failure detection is not performed.

In recent years, however, the construction of corporate networks has become popular, and the demand for leased lines has expanded, and their reliability has become more important. By the way, the new high-speed digital leased line is constantly monitored (parity or the like) for each line, so that failure detection is easy and, therefore, it has high reliability.

[0005] On the other hand, analog dedicated lines can be introduced at a lower cost than digital dedicated lines, and the demand for them is considerably large due to their data capacity. In this analog dedicated line,
A single communication path CODEC is also used for a line terminating device that accommodates a dedicated line for a voice band item. Therefore, reliability is also important for this analog dedicated line, and it is desired that a failure can be easily detected.

Accordingly, (1) Japanese Patent Application Laid-Open No. 62-254538
Japanese Patent Application Laid-Open Publication No. H10-157, discloses a method in which a test signal is applied to an encoder / decoder in a loop when a communication path is in an idle line state, and as a result, it is determined whether or not the test signal has been correctly encoded, thereby preventing a failure of the encoder / decoder. A monitoring apparatus for a single speech codec adapted to detect is disclosed.

(2) Japanese Patent Application Laid-Open No. 61-208936 discloses a method in which a test signal is applied to an encoder when a communication path is in a non-communication state, and this test signal is detected by a decoder output on a receiving side. A single-speech coding / decoding system is disclosed in which a failure of an encoder and a decoder is detected by checking whether a signal has been transmitted within a predetermined time.

(3) JP-A-56-44237 discloses that
The transmission / reception PCM signal is monitored for a predetermined time to detect an empty line, a monitoring signal is sequentially input to the empty line, and the monitoring signal is returned through a codec corresponding to the line and received. A codec monitoring method for monitoring the function of encoding / decoding is disclosed.

[0009]

However, these prior arts (1) to (3) cannot detect a fault in the encoding / decoding circuit unless the relevant line is unused. .

SUMMARY OF THE INVENTION It is an object of the present invention to provide a failure diagnosis apparatus for a single speech path coding circuit capable of detecting a fault in the coding circuit even when using a line.

[0011]

In order to solve the above-mentioned problems, the present invention provides a test signal in a PCM terminal station device for converting a voice signal into a PCM code for transmission and a line termination device for a voice band item dedicated line. A test signal generating means, a test signal superimposing means for superimposing an output of the test generating means on a transmission input signal, a transmitting side encoding means for encoding an output of the test signal superimposing means, and the test signal. Test signal coding means for coding, and whether or not the test signal is included in the output of the transmitting side coding means based on the output of the transmitting side coding means and the output of the test signal coding means And a test signal erasing means for erasing the test signal from the output of the transmitting side coding means.

[0012]

The test signal is superimposed on the transmission input signal, and the superimposed signal is digitally converted by the transmission side coding means.
Then, the monitoring means checks whether or not the digitally converted signal contains a test signal. Then, the test signal is deleted from the digitally converted signal and output to the receiving side.
Then, if it is found by the monitoring means that the test signal is included in the digitally converted signal, the transmitting side encoding means is diagnosed as normal.

[0013]

Embodiments of the present invention will be described below with reference to the accompanying drawings. FIG. 1 is a block diagram of an embodiment of a failure diagnosis device for a single channel coding circuit according to the present invention.

The failure diagnosis device for the single channel coding circuit is
An ammo jack 1 to which a transmission-side analog input signal (4WSIN) is input, a transmission-side transformer 2, a transmission-side variable resistor 3, an analog adder 4, a transmission-side amplifier 5, and a transmission-side encoding circuit ( An A / D converter 6 and a test signal generator 7
, A test signal amplifier 8, and a test signal coding circuit (A
/ D converter) 9 and a failure diagnosis unit 10.

Further, the failure diagnosis unit 10 includes a band-pass filter (BP) for extracting a test signal from the output of the transmitting side coding circuit 6.
F) 11, a test signal detecting unit 12, and a test signal erasing unit (echo canceller) 13 for erasing a test signal from the output of the transmitting side encoding circuit 6.

The transmission side analog input signal input to the bullet jack 1 is input to the analog adder 4 via the transmission side transformer 2 and the transmission side variable resistor 3. On the other hand, the test signal of the predetermined frequency generated by the test signal generator 7 is also input to the analog adder 4. Then, the analog input signal and the test signal on the transmission side are added by the analog adder 4, amplified by the amplifier 5 on the transmission side, converted to a digital signal by the encoding circuit 6 on the transmission side, and become a pseudo digital input signal for transmission. .

The test signal generated by the test signal generator 7 is converted into a digital signal by a test signal encoding circuit 9 via a test signal amplifier 8.

Next, the transmission digital pseudo input signal and the digitally converted test signal are input to the fault diagnosis unit 10.

FIG. 2 is a block diagram of the failure diagnosis unit. The test signal detector 12 detects a level of the test signal extracted by the bandpass filter 11 and detects a level of the pseudo test signal.
A test signal level detecting section 22 for detecting the level of the digitally converted test signal, the level of the pseudo test signal detected by the pseudo test signal level detecting section 21 and the level of the test signal detected by the test signal level detecting section 22. And a test signal detection determination unit 23 that determines whether or not there is a test signal.

When the level comparison results in a match, the test signal is present, that is, the operations of the transmission-side amplifier 5 and the transmission-side encoding circuit 6 are determined to be normal. Is output.

On the other hand, if the level comparison shows that the levels do not match, there is no test signal, that is, it is determined that the transmitting amplifier 5 or the transmitting encoding circuit 6 has failed, and a failure notification signal is output from the test signal detection / determination section 23. You.

Note that a band-pass filter (not shown) is provided on the transmission side of the transmission-side encoding circuit 6, and this filter outputs an audio signal of 300 to 3400 Hz. Therefore, the frequency of the test signal is lower than 300 Hz or higher than 3400 Hz so as not to affect the transmission input signal. However, since the test signal is easily attenuated by this band-pass filter, the test signal detection unit 1
The second pseudo test signal level detection unit 21 adjusts the sensitivity.

The test signal erasing section 13 is a so-called "echo canceller" comprising a subtracting section 24 and an echo estimating section 25. The test signal erasing unit 13 subtracts the digitally converted test signal from the transmission digital pseudo input signal. However, since a slight time difference occurs between the transmission digital pseudo input signal and the digitally converted test signal, the test signal elimination unit 13 simply outputs the test signal. The test signal cannot be erased only by subtraction. Therefore, this echo canceller 13 is used.

The echo canceller 13 estimates a pseudo echo signal in the echo estimating unit 25 from the digitally converted test signal and the residual echo signal output from the subtracting unit 24, and converts the pseudo echo signal into a transmission digital pseudo signal. The test signal is erased by subtracting it from the input signal. The signal from which the test signal has been deleted is output as a normal transmission digital signal output (VFS OUT).

FIG. 3 is a block diagram of an embodiment of the decoding device on the receiving side. Normal processing is performed in the receiving side decoding device. That is, the received digital input signal (VFR I
N) is decoded into an analog signal by the receiving side decoding circuit (D / A converter) 14, and further received via the receiving side amplifier 15, the receiving side variable resistance attenuator 16, the receiving side transformer 17, and the ammunition jack 18. Side analog output signal (4WR OU
Is output as T).

As described above, if the transmitting side amplifier 5 or the transmitting side encoding circuit 6 on the transmitting side is abnormal, it is diagnosed as a failure and a failure notification signal is output. If the configuration is switched to the transmission-side amplifier 5 or the transmission-side encoding circuit 6, high reliability can be obtained even with an analog dedicated line.

[0027]

According to the present invention, a test signal is superimposed on a transmission input signal, the superimposed signal is digitally converted, and it is checked whether or not the digitally converted signal contains a test signal. Since the test signal is erased from the digitally converted signal, it is possible to detect a failure of the single channel coding circuit even when using a line.

[Brief description of drawings]

FIG. 1 is a configuration diagram of an embodiment of a failure diagnosis device for a single channel coding circuit according to the present invention.

FIG. 2 is a configuration diagram of a failure diagnosis unit of the failure diagnosis device.

FIG. 3 is a configuration diagram of an embodiment of a receiving side decoding device of the failure diagnosis device.

[Explanation of symbols]

 Reference Signs List 4 analog adder 5 transmission side amplifier 6 transmission side coding circuit (A / D converter) 7 test signal generation unit 8 test signal amplifier 9 test signal coding circuit (A / D converter) 10 failure diagnosis unit 11 Bandpass filter (BPF) 12 Test signal detection unit 13 Test signal erasure unit (echo canceller) 23 Test signal detection determination unit 24 Subtraction unit 25 Echo estimation unit

Claims (3)

[Claims] 1. A test signal generating means for generating a test signal, a test signal superimposing means for superimposing an output of the test generating means on a transmission input signal, and a transmission side encoding for encoding an output of the test signal superimposing means. Means, a test signal coding means for coding the test signal, and the test signal at the output of the sending side coding means based on the output of the sending side coding means and the output of the test signal coding means. Failure of the single channel coding circuit, including a monitoring means for monitoring whether or not the test signal is included, and a test signal erasing means for erasing the test signal from the output of the transmitting side coding means. Diagnostic device. 2. The monitoring means according to claim 1, wherein said monitoring means extracts said test signal from an output of said transmitting side coding means, and compares a test signal extracted from said extraction means with an output of said test signal coding means. 2. The fault diagnosis apparatus for a single channel coding circuit according to claim 1, further comprising: a comparing unit that performs the comparison. 3. The test signal erasing unit receives the output of the transmitting side encoding unit and the output of the test signal encoding unit, and subtracts the test signal from the output of the transmitting side encoding unit. 3. A failure diagnosis apparatus for a single channel coding circuit according to claim 1, wherein said failure diagnosis apparatus is an echo canceller apparatus for outputting a signal.