JPS5915228B2 - Single channel codec monitoring device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION 15 The present invention relates to a device that constantly monitors the characteristics of a single channel coater and decoder used in a PCM encoding terminal station device.

Conventionally, codecs for PCM encoding terminal equipment are commonly installed on a plurality of communication paths.

A pilot monitoring system is generally used to monitor this type of codec (coater, decoder). The first communication path in the plurality of communication paths sends out a pilot signal while there is no call, and issues an alarm when the level of the received pilot signal falls outside a predetermined range. For this reason, it is necessary to generate a pilot signal, connect the coater and decoder, and determine whether there is a call or no call, and if this method is applied to a single channel codec, all communication paths There were drawbacks such as the need for 30 pieces of information to determine whether a call was made or not, and an analog switch was required to connect the pilot signal to each communication path. Therefore, the present invention aims to improve the above-mentioned drawbacks of the prior art, and aims to improve the above-mentioned drawbacks of the prior art by
It counts the number of 5-crosses and determines the quality of the coater and decoder based on the statistical properties of the audio.Its features include a coater that encodes analog signals into digital signals and a decoder that decodes digital signals into analog signals. A monitoring device for a single channel codec includes (5) means for selecting a monitored channel from the coater and decoder to be monitored; and (b) means for extracting a corresponding analog signal from the digital signal of the selected channel of the coater. a circuit that detects a voiced sound by detecting the level; a circuit that detects the frequency of the signal by counting the number of zero tolerances of the analog signal;
and (c) detecting voiced tones by detecting the analog signal level of the decoder output. a circuit that detects the frequency of the signal by logarithmizing the number of zero crossings of the analog signal; and a decoder alarm generation circuit that generates an alarm when voiced sound is detected and the signal frequency is outside the speech band. A single channel codec monitoring apparatus includes a decoder monitoring circuit.

Examples will be described below with reference to the drawings.

2. Fig. 1 shows an embodiment of the present invention, in which a PCM
A coater monitoring circuit is applied to the encoding terminal equipment. 1 is a coater monitoring circuit, 2 is an analog signal input terminal, 3
is a single channel coater, 4 is a timing circuit, 5 is a time division multiplexing circuit, 6 is a time slot selection circuit,
7 is a zero crossing counting circuit, 8 is a level detection circuit, 9 is a coater alarm generation circuit, 10 is a PCM signal output terminal, 11
is an alarm output terminal.

It is assumed that the coater and decoder have 8 kHz sampling, 83-bit quantization, and logarithmic companding μm1aw is μ=255, 15-line approximation type (CCITT recommendation G7ll).

Regarding the coater, the relationship between analog signals and digitally encoded values is shown in FIGS. 3A and 3B. Here, FIG. 3B is an enlarged view of the vicinity of the origin of FIG. 3A. 3. In the figure, the first bit A of the digitally encoded value represents the positive or negative sign of the analog signal, and when it is 1, it is positive, and when it is 0, it is negative.

The second to fourth bits represent segments, 000 is the segment, 001, 4010, 011
But 100, 101, 110 are I! , 111 represents I, the step width Δi of each segment i is Δ1=2
From then, Δi=21 is taken until Δ8=256.

From the 5th bit to the 8th bit of the digitally encoded value, W
XYZ is the segment IVC, with a step width of Δi, and represents the level within the segment using an inverted binary code. That is, the minimum level within the segment is WXY
Z-1111, the maximum level is WXYZ=0000. To operate the coater monitoring device, the circuit 6 selects the time slot corresponding to the channel containing the coater to be monitored from the primary group PCM signal, and 8
Extract the bit.

by selecting each channel in turn by circuit 6),
All coaters can be monitored in common. The operation of the monitoring circuit for one channel is described below.

The circuit 8 checks the first (sign bit), second (MSB), and third bit in one time slot and determines that the first bit is 1 and the second and third bits are at least 1.
When there are two O's (folding code), assuming that the input signal to the coater is a sine wave, the level is -35 dBm0 or higher. If 16 or more samples within 50 mS (400 samples) are at or above this level, it is determined that this channel is in a communication state and that voiced sound is being input.

The circuit 7 counts the number of zero crossings by focusing on the alternation of the first bit.

The counting time is set to 50 mS, which is shorter than the vowel duration and less susceptible to impulsive noise. The circuit 8 determines that a voiced sound is input, and the number of zero crossings is between 50 mS and 5 to 200 (signal frequency 1).
00H2 to 4KHz), the circuit 9 determines that the coater is defective and issues an alarm. With this configuration, it is possible to easily discover coater defects and generate alarms when the input level corresponds to a talking state but the periodicity is inappropriate, by just determining the 3 bits. . FIG. 2 shows an embodiment of the Tecoder monitoring device, in which 12 is a decoder monitoring circuit, 13 is a demultiplexing circuit, 14 is a decoder, 15 is a speech path selection circuit, 16 is an analog zero-crossing counting circuit, and 17 is an analog level detection circuit. circuit,
18 is a decoder alarm output terminal, 19 is an analog output terminal, and 20 is a PCM signal input terminal. To operate this, the circuit 15 sequentially switches the decoder to be monitored. The following explanation assumes that one channel is selected.

The circuit 17 changes the level of -35dBm0 or higher to 1 every 50mS.
When detected six times or more, a level signal is output to the circuit 9. Circuit 16 sends the number of zero crossings to circuit 9a. circuit 9a
The decoder alarm is sent out under the same judgment conditions as the pass/fail judgment conditions for the coater monitoring circuit. With the above configuration, a decoder failure is detected when the periodicity is inappropriate even though it is assumed that a voiced sound is being output based on the signal level. Well, this method is
Of course, other encoding rules (e.g. A-1aW
13 fold line).

Although the present invention has been described as a common monitoring method for multiple communication paths in the primary group, it is clear that it is also effective as a monitoring method for a single coater or decoder. As explained above, the monitoring method of the present invention is advantageous in that it is simple and economical because it performs monitoring in a normal call state without generating a pilot signal.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of a coater portion of a primary group terminal station including a coater monitoring circuit, and FIG. 2 is a block diagram of a decoder portion of the primary group terminal station including a decoder monitoring circuit. FIGS. 3A and 3B are diagrams showing the relationship between analog signal level and digital encoded value. 1... Coater monitoring circuit, 2... Analog signal input terminal, 3...
...Single channel coater, 4...Timing circuit, 5...Time division multiplexing circuit, 6...
. . . Time slot selection circuit, 7 . . . Zero crossing number counting circuit, 8 . . . Level detection circuit, 9 . .
...Coater alarm generation circuit, 10...PC
M signal output terminal, 11... Alarm output terminal,
12... Decoder monitoring circuit, 13...
Demultiplexing circuit, 14...decoder, 15...
. . . Communication path selection circuit, 16 . . . Analog zero crossing number counting circuit, 17 . . . Analog level detection circuit, 18 . . . Decoder alarm output terminal, 19
...Analog signal output terminal, 20...
PCM signal input terminal.

Claims (1)

[Claims] 1. In a single-channel codec monitoring device that includes a coder that encodes an analog signal into a digital signal and a decoder that decodes the digital signal into an analog signal, (a) means for selecting a monitored channel from the coder and decoder to be monitored; (b) a circuit for detecting voiced sound by detecting the level of the corresponding analog signal from the digital signal of the selected communication path of the coder; a coder monitoring circuit comprising a circuit for detecting the frequency and a coder alarm generating circuit for generating an alarm when voiced sound is detected and the signal frequency is outside the speech band; and (c) detecting the analog signal level of the decoder output. a circuit that detects a voiced sound by counting the number of zero crossings of the analog signal; a circuit that detects the frequency of the signal by counting the number of zero crossings of the analog signal; and a circuit that generates an alarm when a voiced sound is detected and the signal frequency is outside the communication band. 1. A single channel codec monitoring device comprising: a decoder monitoring circuit having a decoder alarm generation circuit;