JPS61258553A - Frequency signal generator - Google Patents

Abstract

PURPOSE:To simplify comparatively the constitution by providing a processing device means for receiving a command of generation of a frequency signal and outputting a digital signal having a repetitive frequency and a waveform shaping means for shaping the generated digital signal and outputting it to an analog line as an analog waveform. CONSTITUTION:When a main processor 10 sends a called number incoming data to a bus 12 together with a calling command, frequency signal generating processor 14 responds thereto and outputs sets of digital signals having a repetitive frequency in response to a number constituting each digit of a called party number to output ports 16 and 18. The digital signals are subjected to high-frequency component elimination by a low group filter 20 and a high group filter 22 respectively, the level is adjusted and inputted to an adder 28. The adder 28 synthesizes signals of both inputs 24, 26 and outputs the result to an output 30 as a multi-frequency signal, that is, a MF signal and the MF signal is sent to a line via a transformer.

Description

DETAILED DESCRIPTION OF THE INVENTION Technical Field The present invention relates to a frequency signal generator, in particular a multi-frequency (MP)
The present invention relates to a frequency signal generator that transmits a signal tone (1.--tone) such as a signal.

BACKGROUND OF THE INVENTION MF multiplication signals are often used in place of dial pulses to transmit, for example, a called party number from a customer premises equipment to a central office or between central offices.

Conventional MF signal generators have used integrated circuits specifically designed as tone tires.

This has a microprocessor that controls the generation of the MF multiplier signal, and requires a large number of control lines, for example, eight input/output ports.

Such a processor naturally outputs the signal that is the source of the MF multiplied signal as a digital waveform, so
In order to send the signal to the telephone line as a signal, it was necessary to install a waveform shaping circuit such as a filter. Therefore, in addition to the dual dedicated integrated circuits, various circuit components such as dedicated operational amplifiers and transistors were required.

OBJECTS It is an object of the present invention to eliminate such drawbacks of the prior art and to provide a frequency signal generator with a relatively simple configuration.

Configuration In order to achieve the above object, the present invention provides a frequency signal generator connected to an analog line and for sending a frequency signal to the line, upon receiving an instruction to generate a frequency signal, generates a repetition frequency corresponding to the frequency signal. The invention is characterized by a frequency signal generating device including a general-purpose processing device means for outputting a digital signal having a frequency signal, and a waveform shaping means for shaping the generated digital signal and outputting it as an analog waveform to an analog line. Hereinafter, a detailed explanation will be given based on one embodiment of the present invention.

Referring to FIG. 1, an embodiment of the frequency signal generation device according to the present invention has a processing device 14 for frequency signal generation connected to a main processing device 10 by a system bus 12, and the image processing devices IO and 14 are For example, it is advantageously implemented in a general-purpose microprocessor system.

The wood flow side device is for transmitting the called party number as an MF signal to an analog communication line such as a telephone line.

Therefore, the main processing device 10 gives the processing device 14 a call instruction command and a signal generation instruction including called party number data.

Processor? 2f14 operates as a slave processor for the main processing device 10. It has output ports 16 and 18 and outputs a digital waveform at a repetition rate corresponding to the called party number data to the output ports 18 and 18.

As is well known, the MF frequency signal consists of a low frequency group and a high frequency group, and the digits of the called party number are represented by a selective combination of two of these frequency signals.

In this embodiment, the processing device 14 outputs a digital signal with a repetition frequency corresponding to the low group frequency signal to the output port 16, and outputs a digital signal with a repetition frequency corresponding to the high group frequency signal to the output port 18. to output,
programmed. The repetition frequency of the output signal is set by its program sequence.

Output capacitors 1B and 18 are connected to a low-group low-pass filter 20 and a high-group low-pass filter 22, respectively. Both low pass filters 20 and 22 each have input 1
It has a function of removing high-frequency components of the digital waveforms, ie, rectangular waves, received at 6 and 18 and shaping them into analog waveforms.

The respective outputs 24 and 26 of the low-pass filters 20 and 22 are connected to an adder 28, which combines the frequency signals obtained from both the low-pass filters 20 and 22 and outputs them as a multi-frequency signal at an output 30. It has a function to output. This multi-frequency signal, or multiple signal tone (dual tone),
The signal is sent from the output terminal 30 via a transformer to a line such as a subscriber line accommodated in a switched network such as a public switched telephone network.

Referring to FIG. 2, a specific example of the configuration of each of the power blocks shown in FIG. 1 is shown. The output port 16 of the processing device 14 is connected to a voltage divider consisting of voltage dividing resistors R1 and R2 connected to a power supply Vcc. It is connected to the low-pass filter 20 from its partial voltage connection point 50 . Similarly, the output port 18 has a voltage dividing resistor R connected to the voltage rAVcc.
3 and R4, and its voltage dividing connection point 51 is connected to the low-pass filter 22.

These voltage dividers are connected to the corresponding output ports 16 and 18.
, which is ultimately used advantageously to adjust the level of the output signal at the output 30 of the device. In other words, by setting the constant of the voltage divider to a desired value, the output signal 3 can be
The level of 0 can be adjusted arbitrarily.

The low-pass filter 20 includes a general-purpose operational amplifier OP1.
It forms the following low-pass filter: operational amplifier OP
The output 52 of 1 is connected to one input 24 of adder 28 via a high-pass filter consisting of capacitor C1 and resistor R5. The reason why such a high-pass filter is provided is as follows. That is, the low-pass filter 20 using the operational amplifier OPI has a high frequency dependence of the signal level output to the output 52, and the output level decreases in a relatively high frequency range. The frequency dependence of the level is removed.

Similarly, the low-pass filter 22 also forms a third-order low-pass filter including a general-purpose operational amplifier OP2.
The output 54 of is connected to the other input 26 of the adder 28 via a high-pass filter consisting of a capacitor C2 and a resistor R6. This high-pass filter is also provided for the reason of eliminating the frequency dependence mentioned above.

Adder 38 also includes a general purpose operational amplifier OP3 and also has a low pass filter consisting of resistor R7 and capacitor C3. This low-pass filter has a function of removing harmonic distortion superimposed on the signal to be synthesized.

Explain the operation. When the main processing unit 10 sends the called party number data along with the calling command to the bus 12, the frequency signal generation processing unit 14 responds by repeating the number data corresponding to each digit of the called party number. output ports 16 and 18 respectively.
Output to. The high frequency components of these digital signals are removed by the low group filter 2o and the high group filter 22, respectively, and the levels thereof are adjusted and input to the adder 28. The adder 28 combines the signals of the two inputs 24 and 26 to produce a multi-frequency signal, that is, an MF multiplied signal, and outputs this as an output 30. This MF multiplied signal is sent to the line via a transformer.

The device can also be advantageously applied to other applications, such as the generation of single frequency tones or single tones. In such an application, processing unit 14 is programmed to output a corresponding digital signal to only one output port 16 or 18 in response to the instruction commands of main processing unit IO. The repetition frequency range of the output signal is advantageously set by its programming sequence.

Such signal tones include, for example, a busy tone, a ring tone, a common line signal, and various other control signals for controlling in-home devices. For example, the embodiment described above was applied to an MF-N dialer in a telephone line. However, in addition to such applications for telephones, it is also advantageous to generate a wake-up signal for a leased line that wakes up a home device that is in automatic reception mode and is on standby, such as in an automatic facsimile machine. Applicable. Also, for example, C
Some of the functions of the modem applied to G2 standard facsimile equipment according to the CITT recommendation, such as the generation of ornate tones and random tones used for training, are effectively applied to handshaking with the other party's terminal. .

As described above, according to this embodiment, a general-purpose processing device and an operational amplifier can be effectively applied without requiring an integrated circuit specially designed as a 1-1 dialer. Further, since the type of frequency signal to be generated is defined by the program of such a general-purpose processing device, it can be effectively applied not only to MF multiplied signals but also to various applications. Furthermore, a two-tree tree is sufficient for the input/output ports interfaced with the processing device, simplifying the device configuration.

Effects According to the present invention, there is no need for an integrated circuit specifically designed as a tone dialer, and a general-purpose processing device or operational amplifier can be effectively applied. Further, the type of frequency signal to be generated is defined by the program of such a general-purpose processing device. Therefore, not only the MF multiplied signal,
Effectively applied to various applications. In addition, a two-tree tree is sufficient for the input/output ports interfaced with the processing device, and the device configuration is simplified.

[Brief explanation of the drawing]

FIG. 1 is a schematic block diagram showing an embodiment of a frequency signal generator according to the present invention, and FIG. 2 is a functional diagram showing a specific configuration example of each functional block in the embodiment shown in FIG. Explanation of symbols of main parts 10.14. , processing device 20.22. , low-pass filter 28, , adder

Claims (1)

[Claims] 1. A frequency signal generating device connected to an analog line and for sending a frequency signal to the line, wherein the device receives an instruction to generate a frequency signal and generates a repetition signal corresponding to the frequency signal. A frequency signal generating device comprising: a general-purpose processing device for outputting a digital signal having a frequency; and a waveform shaping device for shaping the generated digital signal and outputting it as an analog waveform to the analog line. . 2. In the apparatus according to claim 1, the waveform shaping means has a low-pass filter means including a general-purpose operational amplifier, and the digital signal is shaped into an analog waveform by the low-pass filter means. A frequency signal generator characterized by: 3. The apparatus according to claim 1, wherein the frequency signal is a multi-frequency signal, and the processing device means generates a repetition frequency corresponding to a selective combination of a plurality of frequencies constituting the multi-frequency signal. It has two output ports that output digital signals, and the waveform shaping means combines two low-pass filter means connected to the two output ports, respectively, and the outputs of the two low-pass filter means. and adder means for outputting a multi-frequency signal. 4. The apparatus according to claim 3, wherein the analog line is connected to a switching network, and the instruction for generating the frequency signal includes a digit of a called party number in the switching network. Frequency signal generator. 5. The apparatus according to claim 1, wherein the frequency signal is a single frequency signal, and the processing device means has one output for outputting a digital signal with a repetition frequency corresponding to the frequency of the single frequency signal. A frequency signal generating device, comprising: a port; and the waveform shaping means has a low-pass filter means connected to the output port.