JPH06284452A - Identifying circuit for audible sound signal returned from telephone line network - Google Patents

Abstract

PURPOSE:To exactly identify an audible sound signal including a modulated wave which is returned from a telephone line network by individually detecting an intermittent carrier signal and an intermittent modulated signal by a separation detecting circuit, comparing it with a prescribed audible sound mode pattern, and identifying the audible sound signal. CONSTITUTION:Audible sound signals transmitted from telephone lines L1 and L2 are balance/unbalance converted by a coupling transformer 10, and transmitted through an amplifier 11 and a BPF 12, and a 400Hz audible sound signal is rectified and inputted to a smoothing circuit 14 with a large time constant, and a smoothing circuit 16 with a small time constant. A smoothed signal P3, from the circuit 14 is waveform- prepared by a waveform preparing circuit 15, and a signal P4, from the circuit 15 is inputted to a microprocessor 20. On the other hand, an output signal from the circuit 16 is transmitted through a BPF 17, a 16Hz waveform signal P5 is smoothed by a smoothing circuit 18, a signal P6 is transmitted through a waveform preparing circuit 19, and the square wave of a signal P7 is inputted to the microprocessor 20. In the microprocessor 20, the signals P4 and P7 are compared with the prescribed audible sound mode pattern, and the kind of the audible sound signal is identified.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is an improved circuit for identifying an audible sound signal returned from a telephone line network, and in particular, an improved circuit for checking the state of the other party by the returned audible sound signal or performing a predetermined operation. The present invention relates to an audible sound signal identification circuit.

[0002]

2. Description of the Related Art For testing an exchange used for a telephone line, a pseudo call origination / termination device as disclosed, for example, in Japanese Patent Laid-Open No. 2-23761 is used. This is to send various signals to the exchange and detect various signals returned from the exchange to test the operating state of the exchange.

As disclosed in the above publication, this pseudo call originating / receiving apparatus is provided with an audible sound detector for detecting audible sound signals of various mode patterns transmitted from the exchange.

FIG. 4 shows 400 H of the audible sound signal.
A z-system mode pattern is shown, and horizontal or diagonal bands indicate signal continuity.

As shown in FIG. 4, the mode pattern of the audible sound signal is defined by the discontinuity of the signal. Therefore, the conventional audible sound detector detects the discontinuous pattern of the audible sound signal and determines the type of the audible sound signal. (Mode pattern) was identified.

[0006]

However, when the types of audible sound signals increase, there is a problem that the types cannot be defined only by the intermittent pattern of the audible sound signals.

Therefore, in addition to the intermittent pattern, the presence or absence of a modulated wave is added to define the type of the audible sound signal to cope with the increase in the types of the audible sound signal. That is, in the case of the audible sound signal shown in FIG. 4, a part of the carrier signal of 400 Hz is 16 Hz.
Of the band shown in FIG. 4, the carrier signal of 400 Hz in which the horizontal line portion is not modulated, and the shaded portion of the band shown in FIG.
A carrier signal of 0 Hz is shown.

As a result, in some cases, the audible signal differs only in the presence or absence of a modulated wave, and the intermittent pattern becomes the same.

In this case, the above-mentioned conventional audible sound detector can detect the intermittent pattern of the audible sound signal, but cannot detect the presence or absence of the modulated wave, so that it may not be possible to identify the type of the audible sound signal. Is a problem.

For example, the signals (a) to (f) in FIG. 4 can be distinguished from each other only by the intermittent pattern of the audible sound signal even with the conventional audible sound detector, but the signal (g)
And (b) have the same intermittent pattern and cannot be distinguished by the conventional audible sound detector.

In addition, regarding the signal (h) in FIG. 4, the signal continues for the first 0.5 seconds, the signal is interrupted for 4 seconds, and thereafter, the signal continues for 0.05 seconds at intervals of 0.45 seconds. Signals are sent intermittently. However, in the case of a normal audible sound detector, in order to perform signal detection accurately, the first incoming signal is truncated and detection is performed from the next incoming signal. In the case of the audible sound detector of the above publication, the signal sampling is 64
It is performed every millisecond (0.064 seconds). Therefore, when detecting the signal (h), the time (0.
(05 seconds) is too short for the conventional audible sound detector to accurately detect the intermittent pattern of the signal.

Further, in the case of the signal (f), 40
Since the carrier signal of 0 Hz is modulated by the modulated signal of 16 Hz, there is a portion where the amplitude of the carrier signal becomes small even while the signal continues. In this portion, the amplitude of the signal may be lower than the threshold level of the audible sound detector, and the audible sound detector recognizes that the signal is not continuous, so that the intermittent pattern is erroneously detected.

The present invention has been made in view of the above conventional problems, and an object thereof is to provide an audible sound signal identification circuit which can reliably identify an audible sound signal returned from a telephone line network and containing a modulated wave. Especially.

[0014]

In order to achieve the above object, the present invention provides a separation detection circuit for separately detecting an intermittent carrier signal and an intermittent modulation signal included in an audible sound signal, and an intermittent carrier signal and an intermittent modulation signal. A microprocessor for comparing the combination with the signal to a predetermined audible sound mode pattern to identify the audible sound signal.

[0015]

According to the above arrangement, the separation detection circuit detects the intermittent carrier signal and the intermittent modulation signal separately, and the audible sound signal is identified by comparison with the predetermined audible sound mode pattern. Can be accurately identified.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT A preferred embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 shows an embodiment of the audible sound signal discrimination circuit of the present invention. In FIG. 1, a telephone line network L1,
The audible sound signal sent through L2 is balanced and unbalanced by the coupling transformer 10 and then amplified by the amplifier 11. An audible sound signal of 400 Hz system including a carrier signal of 400 Hz is separated from the audible sound signal by passing through the band pass filter 12 of 400 Hz.
The separated 400 Hz audible sound signal is rectified by the rectifier circuit 13 and input to the smoothing circuit 14 having a large time constant and the smoothing circuit 16 having a small time constant.

Here, as the rectifier circuit 13, either a full-wave rectifier circuit or a half-wave rectifier circuit can be used.
In the case of this embodiment, the time constant of the smoothing circuit 14 is 2.2.
It is about milliseconds. Further, the time constant of the smoothing circuit 16 is about 0.2 milliseconds in this case.

The smoothing circuit 14 having a large time constant causes
The carrier signal of Hz is smoothed, and the smoothed audible sound signal is input to the waveform shaping circuit 15 including a Schmitt trigger or the like, and is input to the microprocessor 20 as a shaped square wave signal.

On the other hand, the smoothing circuit 16 having a small time constant outputs a signal having the waveform of the envelope of the carrier signal of 400 Hz which is modulated by the modulation signal of 16 Hz. This signal is separated by passing through a 16 Hz band-pass filter 17, is input to a smoothing circuit 18 having a large time constant, and is smoothed. The time constant of the smoothing circuit 18 is 1
It is about 0.5 milliseconds. The smoothed signal is input to a waveform shaping circuit 19 such as a Schmitt trigger similar to the above, and the microprocessor 2 produces a shaped square wave.
Input to 0.

Here, the circuits from the coupling transformer 10 to the waveform shaping circuit 15 and the waveform shaping circuit 19 constitute the separation detection circuit of the audible sound signal discrimination circuit of the present invention.

The characteristic feature of the present invention is 400H.
The z carrier signal and the 16 Hz modulated signal are separately smoothed during the duration of each signal, and the waveform is shaped into a square wave for detection. Therefore, it is possible to distinguish between a signal containing a modulated wave and a signal not containing a modulated wave. Also, since the signal pattern is identified not by the modulated signal but by shaping it into a square wave, the amplitude of the modulated signal may be below the threshold level of the detector. There is no misidentification of the signal.

Furthermore, since it is not necessary to sample the signal intermittently for signal detection, accurate detection can be performed even when the signal continues for a short time.

FIG. 2 shows how the signals of various parts of the circuit shown in FIG. 1 change. In FIG. 2, the output signal of the bandpass filter 12 is indicated by P1. Signal P1
Indicates a case where a 400 Hz carrier signal modulated with a 16 Hz modulation signal continues for 1 second. This signal P1 is rectified by the rectifier circuit 13, and its output signal is indicated by P2. In the case of this embodiment, a half-wave rectifier circuit is used as the rectifier circuit 13.

The signal after the signal P2 is smoothed by the smoothing circuit 14 is shown as a signal P3. At this stage of the signal P3, the waveform is almost a square wave, but in order to further shape the waveform, the signal P3 is further input to the waveform shaping circuit 15 and is shaped into a clean square wave P4. This signal P4
Is during continuous carrier signal of 400Hz (1 second)
It is a square wave that turns on.

On the other hand, the signal input to the smoothing circuit 16 is
At the exit of the bandpass filter 17, the signal P5 having a waveform of 16 Hz is obtained. The signal P5 is further applied to the smoothing circuit 18 to be smoothed, and the waveform of its output signal is shown by P6. The signal P6 shows how the signal P5 is smoothed. Next, the signal P6 passes through the waveform shaping circuit 19 and then the signal P6.
It is output as a square wave shaped as shown in FIG. This signal P7 is output as a square wave which is turned on only when the audible sound signal includes a modulation signal of 16 Hz.

Here, the bandpass filters 12 and 17 of 400 Hz and 16 Hz are inserted so that an erroneous output signal is not output to the microprocessor due to noise mixed in from the telephone line network.

Next, in order to identify the type of the audible sound signal, the output signals P4 and P7 of the smoothing circuit 14 and the smoothing circuit 19 are connected to the input terminals of the microprocessor 20 shown in FIG.
Enter. In the microprocessor 20, the signal P
4 and P7 to carrier signal of 400Hz and 16Hz
The presence or absence of the modulated signal and the continuous time of the signal are detected and compared with a predetermined audible sound mode pattern to identify the type of the audible sound signal.

That is, as shown in FIG. 4, the audible sound signal sent from the telephone line network is 400 H due to the intermittent carrier signal of 400 Hz and the modulated signal of 16 Hz.
The type is defined by the presence or absence of modulation of the z carrier signal. Therefore, the audible signal is not modulated and 400H
When it is composed of only the z signal, the output of the separation detection circuit is only the signal P4 from the waveform shaping circuit 15. Therefore, the microprocessor 20 can identify the type of the audible sound signal from the intermittent pattern of the square wave of the signal P4.

On the other hand, when the audible signal is composed of the carrier signal of 400 Hz which is modulated by the signal of 16 Hz, the output of the separation detection circuit is the waveform shaping circuit 15.
2 of the signal P4 from the waveform shaping circuit 19 and the signal P7 from the waveform shaping circuit 19
Will contain two square wave signals. Therefore, the microprocessor 20 can identify the type of the audible sound signal from the intermittent pattern of the two signals P4 and P7.

FIG. 3 shows another embodiment of the audible sound signal identifying circuit of the present invention. The same members as those in the embodiment of FIG.

A feature of this embodiment is that the retrigger type one-shot multi 21, 22 is used as a means for extracting the square wave signals P4 and P7 from the signal P2 output from the rectifier circuit 13. By using this retrigger type one-shot multi 21 and 22,
For the carrier signal component of 400 Hz, the square wave signal P4 can be obtained directly from the signal P2. For the 16 Hz modulated signal component, a signal P7 that is a square wave is directly obtained from the signal P5. The microprocessor 20 discriminates the type of the audible sound signal from these signals as described above.

In this case, the quasi-stable period of the retrigger type one-shot multis 21 and 22 may be adjusted to the signal period of 16 Hz, that is, 1/16 seconds. that way,
Even if the 400 Hz carrier signal is modulated at 16 Hz, the retrigger type one-shot multi 21, 22 is always retriggered because the signal peaks every 1/16 second. Therefore, it is not possible to mistakenly recognize that the signal does not continue while the signal continues.

[0034]

As described above, the separation detection circuit detects the intermittent carrier signal and the intermittent modulation signal separately,
Since the audible sound signal is identified by comparison with a predetermined audible sound mode pattern, accurate identification can be performed even if the audible sound signal includes a modulated wave. As a result, it is possible to provide an audible sound signal identification circuit that can reliably identify an audible sound signal that is returned from the telephone line network and that includes a modulated wave.

[Brief description of drawings]

FIG. 1 is a block diagram showing a preferred embodiment of an audible sound signal identification circuit according to the present invention.

FIG. 2 is a waveform diagram showing how a signal changes in each part of the circuit shown in FIG.

FIG. 3 is a block diagram showing another embodiment of the audible sound signal identification circuit according to the present invention.

FIG. 4 is an explanatory diagram of a pattern of an audible sound signal of 400 Hz system.

[Explanation of symbols]

 10 coupling transformer 12, 17 band pass filter 13 rectifier circuit 14, 16, 18 smoothing circuit 15, 19 waveform shaping circuit 21, 22 retrigger type one-shot multi

Claims (1)

[Claims] 1. A separation detection circuit for separately detecting an intermittent carrier signal and an intermittent modulation signal included in an audible sound signal, and a combination of the intermittent carrier signal and the intermittent modulation signal are compared with a predetermined audible sound mode pattern. A discrimination circuit for an audible sound signal returned from a telephone network, comprising: a microprocessor for recognizing the audible sound signal;