JPS6215958A - Dtmf signal transmission equipment - Google Patents

Abstract

PURPOSE:To set variably a sound volume level by using a DTMF signal production circuit (DSP) to generate a DTMF signal. CONSTITUTION:When a high/low group frequency signal (monotone) is outputted from a sound source 25 of a DTMF signal to the DSP 28 in time division multiplex mode, the DSP 28 receives control information (kinds of selection signal to be sent, sound volume level and sending timing or the like) from a call processing control circuit 23, selects the component of an instructed selection signal,calculates the level based on the sound volume level in the control information and synthesizes it to the DTMF signal. The signal generated in the DSP 28 is subjected to timing conversion by the information from a call processing control circuit 23, sent to a trunk line interface circuit 26 through a PCM highway, where PCM inversion is applied and the signal is reproduced into an analog signal and sent.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a DTMF signal transmitting device for transmitting a DTMF signal to a central office line or private line in a private electronic exchange, key telephone device, etc. .

Prior Art FIG. 3 shows the configuration of a conventional DTMF signal sending device. In other words, in this case, a rotary telephone is used as the extension telephone, and from this telephone, the central office line (PB line) is connected.
It shows the connection of individual circuits and the relationship between signal transmission and reception when a selection signal is sent to a telephone and a telephone conversation is made. Extension telephone 11
The dial signal issued by the telephone is received, counted, and converted into a numerical code in the extension interface circuit 12, and then notified to the call processing control circuit 13. When the call processing control circuit 13 determines that this dial signal is a selection signal for the central office line 17, it instructs the central office line interface circuit 12 to make a call, and also sends a call to the central office line interface circuit 12.
In response to this, an instruction is given to send a DTMF signal corresponding to the dial signal issued from the extension telephone 11 to the office line interface circuit 16. Note that analog signals such as voice transmitted and received over the extension and office lines are PCM converted/inversely converted in the extension and office line interface circuits 12 and 16, and are handled as digital signals inside the electronic exchange. Further, a data bus (PCM highway) for transmitting and receiving digital signals is connected to a plurality of extension line/office line interface circuits 12 and 16, and is shared in a time division multiplexed manner. That is, each interface circuit 12, 16 has a predetermined time period for transmitting and receiving data.The time division switching circuit 14 receives the digital signal sent through the data bus, performs timing conversion, and converts the data again. It has a function to send out onto the bus. As a result, the time zone for transmitting and receiving data is converted, and data is converted and connected between terminals (telephones, office lines, etc.).

In addition, instruction and control of timing conversion within the time division switching circuit 14 is performed through the call processing control circuit 13.

Now, in FIG. 3, the DTMF signal sound source 15 is composed of a ROM in which a DTMP signal (analog signal) sent through a central office line or a dedicated line is previously converted into PCM and written in the form of a digital signal. . The DTMF signal is a mixed signal of a high group frequency signal and a low group frequency signal. For example, the selection signal "1" is a mixed signal of a high group frequency signal of 1209 Hz and a low group frequency signal of 697 Hz. By combining four high group frequency signals and four low group frequency signals, 4×4=16 types of DTMF signals can be obtained. Normally, 16 types of DTMF signals are written in the ROM. DTMF signal sound source 15 and time division switching circuit 1
4 are connected by a PCM highway, and a plurality of digitized DTMF signals are always sent to the time division exchange circuit 14 in a time division manner. As a supplementary note, the data series input to the time division exchange circuit 14 is finite, and only a portion of it is occupied.

The transmission of the DTMF signal to the office line interface circuit 16 and the office line 17 will be explained in detail again. The time division switching circuit 14 receives an instruction to send a specified DTMF signal from the call processing control circuit 13 to a certain central office line interface circuit 16, and converts the corresponding data (digital DTMF, signal) sent from the DTMF signal sound source 15. Timing conversion is performed and this data is sent to the office line interface circuit 16. The office line interface circuit 16 that receives and receives this data (digital DTMF signal) performs PCM inverse conversion and sends it to the office line as an analog signal. Also, D
The transmission time of the TMF signal is controlled by switching the connection with the central office line interface in the time division switching circuit 14 (for example, when not transmitting a DTMF signal, transmitting silence to the central office line interface circuit 16). .

Problems to be Solved by the Invention However, in the above-mentioned conventional DTMF signal transmission device,
Since the DTMF signal is converted to PCM in advance and a ROM in which it is written is used, the volume of the transmitted DTMF signal is treated as a constant, and the volume of the transmitted DTMF signal is treated as constant, and the volume is different from that of the installed electronic exchange and other exchanges (central line If there is a central office exchange, the distance from the central office exchange, or if it is a leased line, another private branch exchange), and if operations such as increasing the volume are required, it is difficult to do so easily. There was a problem.

In addition, the time division switching circuit 14 always transfers multiple DTMF signals.
As a result, the PCM highway is occupied and the number of PCM highways increases from the system's perspective, resulting in the problem that the PCM highway is not being utilized effectively.

The present invention solves these problems and provides a PC
The present invention aims to provide an excellent DTMF signal transmission device that can effectively utilize the M highway.
The output volume level of the DTMF signal can be changed by using the DIP and the PCM
The structure is such that the system can be used effectively.

Therefore, according to the present invention, D8P is used to prepare DTMF.
Signals can be mixed and generated, and in the process the volume level can be made variable.

By controlling the generation of DTMF signals as necessary, it is possible to efficiently utilize the PCM and -Iway.

Embodiment FIG. 1 is a block diagram showing an embodiment of the DTMF signal transmission device of the present invention. In order to avoid duplication with the explanation of the conventional example, the operation will be mainly explained with a focus on the process of generating the DTMF signal and sending it to the office line interface circuit. In FIG. 1, the sound source 25 of the DTMF signal is different from that in FIG. 3, and is not a mixed signal of a high group frequency signal and a low group frequency signal of the DTMF signal, but is converted into a digital signal by PCM conversion as each single tone signal. R written as
It shall be composed mainly of OM. From the sound source 25 of this DTMF signal, a high group/low group frequency signal (single tone) is
It is assumed that the signal is output to the TMF signal generation circuit 28 in a time division multiplexed manner. The DTMF signal generation circuit 28 receives control information (type of selection signal to be sent,
When receiving and receiving (volume level, sending timing, etc.), DTM
Among the high group/low group frequency signals sent from the F signal sound source 25, select the component of the designated selection signal, and
The signal is input to the SP 28, and the DSP 28 calculates it based on the volume level in the control information and synthesizes it into a DTMF signal. (See FIG. 2) The signal generated by the DSP 28 undergoes timing conversion based on information from the call processing control circuit 23, and is sent to the central office line interface circuit 26 via the PCM highway. Here, the signal is inversely converted to PCM' and reproduced and sent out as an analog signal.

Further, in the embodiment described above, the DTMF signal generation section is placed at a location separate from the time division exchange circuit 24, and is configured to perform timing conversion and transmission to the PCM highway separately from the time division exchange circuit 24. By adopting this configuration, the PC
It can be used efficiently without occupying the M Highway unnecessarily. Specifically, the timing converter 32 shown in FIG. 2 puts the DTMF signal on the PCM highway at the appropriate timing based on the control information from the call processing control circuit 31. The purpose of this is not to reduce the number of input sequences to the time division switching circuit.

Note that control of transmission time and the like is also performed here.

Effects of the Invention As is clear from the above embodiments, the present invention uses a DSP to generate a DTMF signal, and has the advantage that the volume level can be set variably. Then, by sending the digitized DTMF signal to the ■χ highway without passing through the time division exchange circuit, the DTM
This has the effect that the PCM highway can be used efficiently without being occupied only for the F signal.

[Brief explanation of drawings]

FIG. 1 is a schematic block diagram of an embodiment of the DTMF signal transmitting device of the present invention, FIG. 2 is a detailed block diagram of the same essential parts, and FIG. 3 is a schematic block diagram of a conventional DTMF signal transmitting device. It is. 21...Extension telephone (dial/pulse type), 22...
... Extension interface circuit, 23, 31... Call processing control circuit, 24... Time division switching circuit, 25.33.
...DTMF signal sound source circuit, 26... Office line interface circuit, 27... Office line, 28... DTMF signal generation circuit, 32... Timing converter, 34-DSP (
Digital Signaling Process
ssor) section, 35, 36...◆Data bus. Name of agent: Patent attorney Toshio Nakao and 1 other person No. 1
figure

Claims (1)

[Claims] The signals of the high group frequency and low group frequency components of the DTMF signal are PCM modulated and digitally encoded in advance, and the data is written into a ROM. This ROM is coupled to a digital signal processor, and the high group frequency and low group frequency components of the DTMF signal are encoded in advance. A DTM configured to mix frequency and low group frequency component signals to create a DTMF signal and send it to a private office line, etc.
F signal sending device.