KR100205063B1 - A pcm tone generator - Google Patents

Abstract

The present invention relates to a PCM tone generating apparatus that can easily generate various audible tones to be sent to the telephone subscriber from the exchange side in connection with subscriber line matching. The PCM tone generating apparatus according to the present invention is an individual PCM tone output from the first PCM tone generator 10a and the second PCM tone generator 10b for generating individual PCM tones from a preset sampling period and counter value of the PCM. It is characterized by comprising an adder 20 for generating the various audible tones by adding the data, wherein the first PCM tone generator 10a and the second PCM tone generator 10b are a predetermined number of PCMs. An up / down counter 12 for generating tone data having a periodic waveform by maintaining an up count state for a half cycle and a down count state for the other half cycle to generate a pulse corresponding to a sampling period of The LSB generates a clock corresponding to half of the above counter value according to the counter value set in the above, and each time a pulse corresponding to the sampling period of the PCM occurs, A clock counter 11 for providing a clock signal to the operation counter 12 and a state counter for controlling the up / down counter 12 to operate in an up count state for a half cycle and a down counter state for the other half cycle. (13) and a toggle control unit 14 for controlling the state counter 13 to alternate between the up state and the down state every time the count counter 13 counts to generate pulses corresponding to a predetermined number of PCM sampling cycles for a half period. It is composed of

Description

A PCM tone generator

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pulse code modulation (PCM) tone generating device. In particular, a PCM tone generating device capable of simply generating various audible tones to be sent to a telephone subscriber from an exchange side in connection with subscriber line matching. It is about.

1 is a block diagram showing a subscriber line matching device of an exchanger including a PCM tone generating device according to the prior art, wherein the configuration from the subscriber line matching device of the current exchange to the telephone gangja is the same as that shown in FIG. Do. That is, as a block diagram showing the subscriber line matching device of the exchange, the configuration from the subscriber line matching device of the current exchange to the telephone subscriber is the same as that shown in FIG. That is, the path from the subscriber line matching device to the telephone subscriber of the exchange is inputted to the PCM codec (4) through the MUX (3), converted into an analog signal, and then connected to the subscriber matching controller (5). Is passed through the subscriber loop to the receiver of the telephone subscriber 6, which is output as voice back to the subscriber's ear. Conversely, the voice of the telephone subscriber 6 is inputted to the subscriber matching controller 5 through the transmitter of the telephone and the subscriber loop, and then again to the PCM codec 4 to be converted into PCM voice data, and then the MUX 4 Are multiplexed and passed to the switch in the exchange. At this time, the basic tone to be provided to the telephone subscriber 6 at the exchange side is dial tone, ring tone and busy tone, and may provide various services by generating a special tone according to the exchange. do.

In the related art, these various tones are converted into PCM data using a special device, and stored in a specific area inside the dedicated ROM 2, and, if necessary, the PCM of the required tones using the address and read signal generator 1 is required. The PCM tone data in which the data is stored is read and provided to the PCM codec 4 through the MUX 4, so that the method of delivering the data to the telephone subscriber 6 is mainly used.

In the case of the above-described conventional technique, not only a special device for PCM data of various tones to be provided to the telephone subscribers on the exchange side is required, but also the addition and deletion of additional services using the tones require PCM tone data. Not only needs a special device for data conversion, but also adds and deletes additional services using tones. In addition to the dedicated ROM where PCM tone data is stored, the program for controlling them is replaced. There was a problem to stop the system. In addition, since a dedicated memory such as a ROM is used, it is difficult to make an ASIC and has a problem of low economic efficiency.

After all, the present invention is to solve the above problems of the prior art, the object of the present invention, there is no need for a special additional device, there is no need to stop the system even when adding and deleting additional services using the tone, Not only can it be easily ASIC, but also provides a PCM tone generator that can easily generate tone data with various frequencies.

1 is a block diagram showing a subscriber line matching device of an exchange including a PCM tone generating device according to the prior art.

2 is an overall block diagram of a subscriber line matching device of an exchange including a PCM tone generating device according to a preferred embodiment of the present invention.

3 is a block diagram of a PCM tone generator of the PCM tone generator of the present invention.

* Explanation of symbols for main parts of the drawings

1: Address and read signal generator 2: PCM tone data storage ROM

3: multiplexer (MUX) 4: PCM codec (CODEC)

5: subscriber line matching controller 6: telephone subscriber

10a, 10b: PCM tone generator 11: clock counter

12: up / down counter 13: status counter

14 toggle control 20 adder

PCM tone generating apparatus according to the present invention, which achieves the above object, various audible tones including dial tone, ringback tone and busy tone to be provided to telephone subscribers at the exchange side. A PCM tone generator for generating a digital signal, comprising: a first PCM tone generator and a second PCM tone generator for generating individual PCM tones from a preset sampling period and a counter value of a PCM, and the first PCM tone generator and the second PCM And an adder for generating the various audible tones by adding the individual PCM tone data output from the tone generator.

In this case, the first PCM tone generator and the second PCM tone generator maintain the up count state for half a period and maintain the down count state for the other half period so that pulses corresponding to a predetermined number of PCM sampling cycles are generated. An up / down counter for generating tone data having a waveform and a clock corresponding to half of the above counter value in its least significant bit (LSB) according to a preset counter value are generated in the PCM sampling period. A clock counter for providing the clock signal of the up / down counter whenever a corresponding pulse occurs, and for controlling the up / down counter to operate in an up count state for a half cycle and a down counter state for the other half cycle. Status counter and pulses corresponding to the sampling cycles of a certain number of PCMs are generated during a half cycle. For it is preferred to consist of a toggle for controlling to alternately change control up state and a down state whenever the above-mentioned state counter count.

Hereinafter, a preferred embodiment of the PCM tone generating apparatus according to the present invention will be described in more detail with reference to the accompanying drawings.

The frequencies used in the various tones provided to the telephone subscribers at the exchange side are shown in Table 1 below. As shown in Table 1 below, each tone comprises two combinations of four frequencies.

FIG. 2 is a block diagram of an entire subscriber line matching device of an exchange including a PCM tone generating device according to a preferred embodiment of the present invention.

As shown in FIG. 2, the PCM tone generator according to the present invention includes a first PCM tone generator 10a and a second PCM tone generator for generating individual PCM tones from preset sampling periods and counter values of the PCM. 10b, and an adder 20 for generating the various audible tones by adding the individual PCM tone data output from the first PCM tone generator 10a and the second PCM tone generator 10b. That is, the adder 20 is used to add two tone data values, since the general tones are used by combining two frequencies.

3 is a block diagram of PCM tone generators 10a and 10b in the PCM tone generator of the present invention.

Typically, PCM is sampled at a cycle of 8KHz, or 125μsec, which is 2857μsec at 350Hz, and 22.856 8KHz pulses are generated within this period. However, most PCM codecs 4 are composed of 8-bit A / D and D / A converters. In this case, there are 256 quantize levels, so that each tone is represented by the sum of two tones. The tone can be thought of as having 128 quantization levels.

The various tones described above do not matter whether they are sinusoidal, triangular, or square, but are sensitive only to the frequency of the human ear signal, and continue during the half cycle using the up / down counter 12. Maintaining the up state and keeping it down during the rumination can produce a triangular tone with a simple circuit configuration. For example, in the case of 350KHz, since 22..856 / 2 = 11.428 8KHz pulses are generated during the half cycle, the up / down counter 12 must add or subtract 11 levels when one 8KHz pulse is generated. . That is, eleven clocks should be provided for every 8 KHz pulse to the up / down counter 12.

This function is performed by the clock counter 11 shown in FIG. 3. The operation principle is to write a value to the clock counter 11 so that the clock counter 11 can count 22 every 8 KHz. 11 clocks are generated in the LSB bit of 11). In this case, since the up / down counter 12 needs to operate in an up count state for half a cycle and a down counter state for the other half cycle, a signal for controlling this is required, which is controlled by the state counter 13. . Since 11.428 8KHz pulses are generated during the half period, the state counter 13 can count 11, and each time, the coggle control unit 14 is configured to alternate between the up state and the down state.

With the above configuration, the up / down counter 12 generates individual tone data in the form of periodic triangle waves having about 128 levels.

The output of the up / down counter 12 of the PCM tone generator 10a is sent to the adder 20 at a period of 8 KHz, and is input from another PCM tone generator 10b having the same configuration. It is added with the output of the down counter 12 to generate various tones.

In the present invention, the data value written to the clock counter 11 and the data value written to the state counter 13 are determined by the method described above, and the operation of writing the value to the counter itself is performed by the PCM tone generators 10a and 10b. Since it is not configured by a memory but simply by a plurality of counters, it has the advantage of being able to control the system without stopping the system externally by a processor or a switch, thereby adding and deleting additional services by tone. It can be done easily.

In addition, unlike in the case of using a memory as in the prior art, it is not necessary to have a special additional device for acquiring PCM tone data, and since it is composed of a plurality of simple counters, it is easier to make ASIC and provides a PCM tone generating device economically. can do.

As described in detail above, the present invention, unlike the conventional method, can easily generate a variety of tones having a variety of frequencies, easy to change the frequency of the tone to enable additional services using a variety of tones, easy ASIC It is possible to economically provide a PCM tone generating device. In addition, the switch or the processor can be changed without stopping the system when necessary for various audible tones, it has the effect that does not require a separate special device for generating PCM tone data.

Therefore, the PCM tone generating apparatus of the present invention can be effectively applied not only to the subscriber service of the existing exchange, but also to a service such as a newly emerging wireless subscriber network.

Claims (2)

In the PCM tone generating apparatus for generating various audible tones including dial tone, ringback tone and busy tone, which must be provided to telephone subscribers at the exchange side, sampling of a PCM set in advance The first and second PCM tone generators for generating individual PCM tones from periods and counter values, and the individual PCM tone data output from the first PCM tone generator and the second PCM tone generator, are added to the various audible signals. PCM tone generating device, characterized in that consisting of an adder for generating a tone. The apparatus of claim 1, wherein the first PCM tone generator and the second PCM tone generator maintain an up count state for half a period so as to generate pulses corresponding to a predetermined number of PCM sampling cycles, and maintain a down count state for the remaining half cycle. An up / down counter for generating tone data having a periodic waveform, and a clock corresponding to half of the above counter value in its LSB according to a preset counter value, and corresponding to the sampling period of the PCM. A clock counter for providing the clock signal of the up / down counter whenever a pulse is generated, and a state for controlling the up / down counter to operate in an up count state for a half cycle and a down counter state for the other half cycle. To generate counters and pulses corresponding to sampling cycles of a predetermined number of PCMs for half a cycle And a toggle control unit for controlling the state counter to alternate between an up state and a down state each time the count is counted.