JPH0294743A - Dtmf signal receiver - Google Patents

Abstract

PURPOSE:To prevent a disabled reception and a malfunction by outputting a tentative reception signal representing a request of remote control when a specific frequency is detected. CONSTITUTION:The output of a BPF 11 for specific frequency is inputted to a specific frequency power detection section 12, which sends a signal to a control section 13 when the input is larger than a threshold level. A control section 13 outputs a signal representing the reception of the DTMF signal by a low- order group from a control output terminal 15 when the signal is consecutive for a prescribed time. The output is used as a tentative reception signal for remote control request from an opposite party and the output excludes the noise element at the reception of the DTMF signal. Then a remote control DTMF signal is received to prevent the occurrence of the malfunction or the like even in the equipment of a comparatively simple signal identification means.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention is directed to dual tone multi-frequency (D
The present invention relates to a DTMF signal receiving device that receives a DTMF signal for remote control of an answering machine or the like while outputting a voice response.

[Conventional technology]

Conventionally, such a DTMF signal receiving apparatus determines a DTMF signal only by identifying high group frequencies and low group frequencies.

FIG. 3 is a block diagram of a DTMF signal receiving apparatus for explaining an example of such a conventional technique.

As shown in FIG. 3, the input signal input from the telephone line to the input terminal 1 is level-adjusted by the input 11 adjustment section 2, and then input to the high group band pass filter 3 and the low group band pass filter 4. Each of these passes only high and low frequencies. This output is input to a high group zero cross detection section 5 and a low group zero cross detection section 8, respectively, and is outputted from these detection sections 5.8 when this input crosses the AC neutral point. The high group frequency determining section 6 and the low group frequency determining section 9 count the number of zero crosses, determine the frequency, and output it to the control section 13'. In addition, the outputs of each bandpass filter (BPF) 3.4 are also input to the high group power detection section 7 and the low group power detection section 10, respectively, and in these parts, when the input power is larger than a preset value, Each is output to the control section 13'. In the control section 13', when the signal input power is sufficiently large and the frequencies of the high group and the low group are appropriate, the DT
Assuming that the MF signal has been received, a DTMF decoded signal is output to the output terminal 14.

4 is a block diagram of an answering machine using the DTMF signal receiving device shown in FIG. 3.

As shown in FIG. 4, when an incoming call is received via a predetermined telephone line, it is detected by the ringing signal detection circuit 21, and the control unit 2
An incoming call detection signal is sent to 2'. The control section 22' outputs a predetermined control signal based on the incoming call detection signal, and the hook switch 43. It is sent to the response voice device 28 and the recording device 29. This hook switch 23 is closed via the control signal and the answering voice device 28 is activated. As a result, the predetermined response voice output from the response voice device 28 is transmitted from the speech circuit 26 to the dial circuit 2.
5. Via the bridge circuit 24 and the closed hook switch 23, it is sent to the other party via the telephone line.

At the same time as this response is sent, the recording device 29 also becomes operational.

On the other hand, when receiving remote control from the other party, the DTMF signal transmitted from the caller side is transmitted to the hook switch 23. DTMF signal receiving device 2 via bridge circuit 24, dial circuit 25 and speech circuit 26
7' and is decoded as digital data as explained in FIG. In addition, the DTMF signal receiving device 27
The DTMF decoded signal outputted from the recording device 2 is inputted to the control section 22', and the control section 22' outputs a predetermined control signal based on the DTMF decoded signal.
sent to. The recording device 29 is controlled by the control signal and performs operations such as sending out recorded contents.

[Problem to be solved by the invention]

The above-mentioned conventional DTMF signal receiving apparatus had the following problems when applied to the answering machine shown in FIG.

That is, the speech circuit 2 used in an answering machine
6 is a type of bridge circuit for separating and combining 2-4 wires, and is terminated by an approximation of the characteristic impedance of the telephone line. If this termination impedance is equal to the characteristic impedance of the telephone line, there will be no loss from the 2nd line side to the 4th line side, from the 4th line side to the 2nd line side, or there will be no reflection from the 4th line side to the 4th line side.

However, since the line impedance of a telephone line is not constant, it is normal to generate the above-mentioned reflection9. Therefore, if a DTMF signal is received from the other party while the response voice is being output, the voice signal due to the reflection The levels of the DTMF signals may be close to the same level. In this case, there is a drawback that the DTMF signal receiving device 27' may become unable to receive signals or may malfunction due to reception output errors.

The purpose of the present invention is to prevent such inability to receive data and malfunctions.
An object of the present invention is to provide a TMF signal receiving device.

[Means to solve the problem]

The DTMF signal receiving device of the present invention receives a multi-frequency signal from an input terminal and identifies high group frequencies and low group frequencies.
The MF signal receiving device includes means for identifying the high frequency group and the low group frequency, means for determining a specific DTMF signal, and means for outputting the determination result separately from the DTMF output during normal operation. It consists of

That is, the present invention includes a specific frequency bandpass filter that detects the presence or absence of a signal of a specific frequency in a DTMF signal, and a specific frequency power detection section, and when this specific frequency is detected, a request for remote control is issued. The provisional reception has a function that outputs a signal to indicate that there has been a reception.

〔Example〕

Next, embodiments of the present invention will be described with reference to the drawings.

FIG. 1 is a block diagram of a DTMF signal receiving apparatus for explaining one embodiment of the present invention.

As shown in FIG. 1, in this embodiment, a multi-frequency signal is input to an input terminal 1, and an input adjustment section 2. Takagun BPF3. Low group B
PF4. High group zero cross detection section 5, high group frequency determination section 6
．． High group power detection section 7°Low group zero cross detection section 8. Low group frequency determining section 9° low group power detecting section 10. Although it is the same as the conventional example described in FIG. 3 in that it includes a control section 13, it differs in that it is additionally provided with a specific frequency BPF II and a specific frequency power detection section 12.

In such a device, the operation when receiving a DTMF signal is similar to that of the conventional example described above.The present embodiment differs from the conventional example in that it includes a bandpass filter 11 for a specific frequency. For example, when using a bandpass filter for 941Hz (this corresponds to o, *+# of telephone number input), when this signal is input, it is obtained as the output of this filter 11, and the specific frequency (this Case 941
Hz) is input to the power detection section 12. This power detection section 12 outputs a signal to the control section 13 when the input is larger than a preset threshold value. Control unit 13
If this signal continues for a certain period of time (for example, 100 ms), a signal indicating that the low group has received a 941 Hz DTMF signal is output from the control output terminal 15. This output is used as a signal to temporarily accept a remote control request from the other party, and as described later, this output eliminates noise elements when receiving DTMF, and then receives the DTMF signal for remote control.
Malfunctions do not occur even in devices with relatively simple signal identification means, such as the zero-cross detection method of the conventional DTMF signal receiving device described above.

In the embodiment shown in FIG. 1, the specific frequency BPF
Although the embodiment has been described in which the II and the specific frequency power detection section 12 are placed in the low group block, malfunctions can be similarly prevented even if these are placed in the high group block.

FIG. 2 is a block diagram of an answering machine using the DTMF signal receiving device shown in FIG.

As shown in FIG. 2, this answering machine has a ringing signal detection circuit 21. Control unit 22. Hook switch 23. Bridge circuit 24. Dial device 25° speech circuit 26. D
TMF signal receiving device 27° response audio device 28. It is configured to include a recording device 29.

The operation of such an answering machine when a call is received is the same as that of the conventional answering machine described above, so a description thereof will be omitted. In short, the difference from the conventional method is that the response voice device 28 requests remote control while outputting, for example,
When the low group frequency is sent as a DTMF signal of 941 Hz, the 941 Hz received signal (the output of the terminal 15 in FIG. When signal 9 is input, the response audio device 28 is temporarily stopped as a DTMF signal is input.After that, if a DTMF signal is detected continuously, the above-mentioned control is performed on the recording device depending on the signal content. 29, and if no DTMF signal is received for a certain period of time after stopping at -
It is determined that the MF signal receiving device 27 has malfunctioned due to the impedance mismatch described above, and the response audio device 28 is operated again.

In this way, by having a function that temporarily stops the noise element (in this case, response audio output) and monitors the situation when a specific frequency is detected, it is possible to prevent malfunctions when receiving a DTMF signal. Can be done.

It is known that the probability that a specific frequency (941 Hz in this embodiment) is continued at a constant power for a certain period of time is low in a normal conversation in a fluctuating audio signal. Furthermore, even if a remote control request is tentatively accepted due to an abnormal occurrence, it can be eliminated by performing the above-described control.

〔Effect of the invention〕

As explained above, the present invention has a bandpass filter that detects only a signal of a specific frequency (941 Hz in this embodiment), and when this signal is detected, a signal is output to temporarily accept a remote control request signal. By this,
This signal makes it possible to eliminate external noise requirements,
Since the DTMF signal can be received in a clear state when receiving it, there is an effect that malfunctions in receiving the DTMF signal can be eliminated.

Determination unit, 10... Low group power detection unit, 11... Specific frequency band pass filter, 12... Specific frequency power detection unit, 13... Control unit.

[Brief explanation of drawings]

FIG. 1 is a block diagram of a DTMF signal receiving device for explaining an embodiment of the present invention, and FIG. 2 is a block diagram of a DTMF signal receiving device shown in FIG.
A block diagram of an answering machine using an F signal receiving device,
FIG. 3 is a block diagram of a DTMF signal receiving device for explaining a conventional example, and FIG. 4 is a block diagram of an answering machine using the DTMF signal receiving device shown in FIG. 3. 1... Input terminal, 2... Input adjustment section, 3... High group band pass filter (BPF), 4... Low group band pass filter (BPF), 5... High group zero cross detection section , 6... High group frequency determination section, 7... High group power detection section, 8... Low group zero cross detection section, 9... Low group frequency - Xianghui Hotaru

Claims (1)

[Claims] In a DTMF signal receiving device that receives a multi-frequency signal from an input terminal and identifies a high group frequency and a low group frequency, a means for identifying the high group frequency and the low group frequency;
A DTMF signal receiving device characterized by comprising means for determining a TMF signal and means for outputting the determination result separately from a DTMF output during normal operation.