KR100251730B1 - Apparatus and method for detecting dtmf signal in digital trunk - Google Patents

Abstract

PURPOSE: An apparatus and a method for detecting a DTMF(Dual Tone Multi-Frequency) in a digital trunk are provided to remove a channel part of an optical transmission device in the trunk of a switching center, and make the switching center connected directly to the transmission device, by enabling the DTMF to be detected in an UDLC manner. CONSTITUTION: A line decoder(310) decodes the channel data received in a time sharing manner. A multiplexor(312) selects the decoded channel data in response to a counted value, and then outputs the channel data selected. A counter(314) counts a clock using a synchronization signal, and outputs the counted value. A latch part(316) latches the output from the multiplexor(312) so that this output can have a predetermined frequency and a duty cycle. A digital-to-analog counter(318) converts the data signal applied from the latch part(316) to an analog signal. A DTMF reception part(320) detects a DTMF signal from the analog data applied from the counter(318). A buffer(324) stores the DTMF detected by the part(320) and the counted value inputted from the counter(314). A CPU(326) converts the data stored in the buffer(324) to signaling data.

Description

D.M.F detection device and method in digital trunk

TECHNICAL FIELD The present invention relates to an interface apparatus and method of a transmission equipment and an exchange, and more particularly, to an apparatus and method for detecting DTMF in a digital trunk of an exchange.

In general, a transmission system including an exchange and an optical transmission device has a configuration as shown in FIG. 1. The process of transmitting data generated from the subscriber side to the exchange through the optical transmission device will be described below.

The data generated from the subscriber station is converted into optical data through the optical transmitter channel unit 150 and the common unit 140 and output to the optical transmitter common unit 130. Optical data is transmitted between the common unit 140 and the common unit 130 through the optical transmission path STM-1, and the common unit 130 converts the optical data into electrical data and converts the optical data into electrical data through the E1 channel unit (E1). 120). Meanwhile, the channel unit 120 transmits the electrical data received through the E1 to the switch 110 through the telephone line.

In this case, as shown in FIG. 2, since the E1 connection is usually present in the switch 110, the 11-inch rack 4 to 5 size optical transmission device channel unit 120 for interfacing the E1 and the telephone line is unnecessary. This can be called.

However, the reason for the continuous use of the channel unit 120 is that even in the case of E1, the signaling (signalling) between the exchange (signalling) using the CCS method, the optical transmission device to handle only the hook-on / off by signaling (signalling) Use the UDLC method.

For this reason, the switching between the switching unit 110 and the channel unit 120 connected by a telephone line should be implemented by a CCS method using the switching unit 110, and the channel unit 120 and the optical transmission device are in common. Since the signaling between the units 130 must be performed by the UDLC method used in the optical transmission device, the channel unit 120 is required.

The UDLC method is a method of transmitting a set or reset signal corresponding to the signaling whether the hook-on / off, and the CCS method is an 8 bit (8 bits) between the trunk (trunk) and trunk (trunk) message In the method of sending and receiving bit by bit, the message is processed as hook-on / off and DTMF data.

Therefore, the main function of the channel unit 120 was to detect a DTMF signal transmitted by the UDLC method and transmit the CCMF method.

As described above, due to the difference in the signaling used in the exchanger and the optical transmission device, there is an inconvenience in increasing the installation cost and managing the optical transmission device due to the need to continuously use the unnecessary optical transmission device channel part.

Accordingly, an object of the present invention for solving the above problems is to provide a device for detecting the D.M.F. by the U.D.C. (UDLC) method in the digital trunk of the switchboard to provide a channel portion of the optical transmission device. Exclude and implement the direct connection between the exchange and the optical transmission device.

Another object of the present invention is to provide a method for detecting a D.M.F. by the U.D.C. (UDLC) method in a digital trunk of an exchanger to exclude the channel portion of the optical transmission device, and to eliminate the exchange and the optical transmission device. The implementation is to connect directly.

1 is an association diagram of a conventional exchanger and an optical transmission device.

FIG. 2 is a typical configuration diagram of the exchanger shown in FIG. 1.

3 is a block diagram of a D.M.F. detection apparatus in a digital trunk according to an embodiment of the present invention.

4 is a signal waveform diagram used in FIG.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings. First of all, E1 (Europeon Level 1) and T1 (Telephon Level 1) described below mean that time division multiplexing means.

The E1 is a European channel with 32 channels of PCM method and the transmission rate is 2.048 megahertz (MHz), and the T1 is a North American method with 24 channels of the PCM method and the transmission rate is 1.544 megahertz (MHz).

In the digital trunk according to an embodiment of the present invention, the DTMF detection apparatus includes a line decoder 310, a multiplexer (MUX) 312, a counter 314, as shown in FIG. 3. Latch 316, Digital / Analog Converter (D / A Converter) 318, DTMF Receiver 320, Control Logic 322, Buffer 324, Central Processing Device (CPU) 326.

The line decoder 310 decodes data received through E1 or T1 and outputs D _in composed of 30 or 24 channels. The MUX 312 outputs data of the selected channel by selecting a specific channel based on a count value of D _in composed of the 30 or 24 channels to be input. The counter 314 counts 20 msec periodically using 600 msec as a synchronization signal when using E1, and outputs the counted count value by counting 20 msec periodically using 480 msec as a synchronization signal when using T1. The latch unit 316 sequentially latches data of a specific channel output from the MUX 312. The D / A converter 318 converts the digital channel data output from the latch unit 316 into analog channel data and outputs the analog channel data. The DTMF receiver 320 detects and outputs a DTMF from the analog channel data. The buffer 324 records DTMF data applied from the DTMF receiver 320 and a count value applied from the counter 314, that is, a channel number, and records the recorded DTMF data and channels under the control of the CPU 326. Print the number. The CPU 326 periodically reads DTMF data and channel numbers from the buffer 324 in a polling or interrupt manner. The control logic 322 prevents the same DTMF from being sequentially detected through the DTMF receiving unit 320 and applied to the buffer 324.

4 is a diagram illustrating waveforms of signals generated by an embodiment of the present invention.

Hereinafter, an embodiment according to the present invention will be described in detail with reference to the above-described configuration.

The channel data consisting of 30 or 24 channels received from the E1 or T1 trunk is decoded and output through the line decoder 310.

The channel data consisting of the 30 channels or the 24 channels output are applied to the MUX 312 and sequentially multiplexed one channel by a counter value provided from the counter 314.

First, when the channel data uses E1 consisting of 30 channels, the operation of the MUX 312 and the counter 314 will be described with reference to FIG. 4.

When the first clock 1T is applied, the counter 314 outputs counter values Q _{0 to} Q ₄ of "0" for 20 msec. The MUX 312 outputs a zero channel of the channel data of the 30 channels input from the line decoder 310 to the latch unit 316 according to the counter values Q _{0 to} Q ₄ of the output “0”.

Also, when applied to the two second 2T clock the counter 314 and outputs the Q ₀ ~Q ₄ of "1" for 20msec, the MUX (312) by Q ₀ ~Q ₄ of the "0" is the first channel Output to the latch unit 316.

That is, the counter 314 increases the count value by one by the input clock, and the MUX 312 increases the channel by one by the count value increased by the clock and outputs channel data of the corresponding channel.

By the above operation, the channel data composed of 30 channels for the synchronization signal 600 msec is output in the order of channels in the order of 20 msec. Here, 20 msec per channel is defined. The DTMF receiver 320 must maintain the DTMF for at least 20 msec. This is because the DTMF can be detected normally. The period of 1 to 30T is set to 600 msec because the user presses at least 0.6 seconds when the user presses the digit of the telephone.

On the other hand, even when the channel data uses T1 composed of 24 channels, the operation of counting a clock through the counter 314 and outputting a channel selected by the counted count value is performed in the same manner as in the case of E1.

However, since T1 is composed of 24 channels, channel data corresponding to 24 channels is sequentially output for 480 msec at a period of 20 msec.

Therefore, whether to use E1 or T1 should be set in advance to determine whether to use 600 msec or 480 msec as a synchronization signal. The determining method may be a method of using a jumper or a method of using a digital multiplexer. In the case of using the jumper, selection can be made by the user directly operating the jumper, and in the case of using the digital multiplexer, switching can be made at the request of the user. Of course, when using E1 and T1 in common, the line decoder 310 must also be implemented to use E1 and T1 in combination.

As described above, the use of E1 or T1 is different only in the period of the synchronization signal, and thus all operations are the same. Therefore, the following description will be given on the assumption that E1 is used.

The channel data sequentially output from the MUX 312 by one channel is applied to the latch unit 316, and the applied channel data is latched to have 64 kilohertz (KHz) and 50 duty cycles.

Each channel data sequentially latched from 1 to 30T through the latch unit 316 is applied to the D / A converter 318 implemented as a PCM combo codec and converted into analog channel data. . The conversion of digital channel data into analog channel data is because a general-purpose DTMF receiver that detects DTMF typically detects an analog DTMF.

The channel data converted into the analog form is applied to the DTMF receiver 320, and the DTMF included in the channel data is detected through the DTMF receiver 320.

Of course, the CPU 326 initially performs control for the initials of the DTMF receiver 320. When the DTMF is detected by controlling the DTMF receiver 320 in hardware, the detected DTMF is provided to the buffer 324.

If the DTMF is detected through the DTMF receiver 320, the count value of the counter 314 is read as a channel number when the DTMF is detected, and the detected DTMF and the channel number are buffers having a first-in first-out (FIFO) structure. 324 are stored.

In addition, if the DTMF detected once through the DTMF receiver 320 is continuously detected, the control logic 322 records only the first DTMF detected through the DTMF receiver 320 in the buffer 324 and blocks the DTMF detected later. The DTMF receiving unit 320 is controlled to perform the control.

The reason for placing the control logic 322 is that if the user presses one key for a long time, the same DTMF is continuously detected, and if the detected DTMF is continuously recorded in the buffer 324, the buffer 324 is This is to prevent it from being pulled up easily.

By the above operation, the CPU 326 periodically accesses the buffer 324 in a falling or interrupting manner with the channel number and DTMF recorded in the buffer 324. Read the assigned channel number and DTMF.

Accordingly, with the hook-on / off signal generated in the UDLC method, the CPU 326 converts the channel number and DTMF into a message form and overwrites the signaling data by the CCS method. Can be accessed at the E1 trunk level.

Of course, the embodiment according to the present invention can be easily applied to a general E1 transmission device as well as an optical transmission device.

In addition, in the above-described embodiment, the configuration of one trunk has been described. However, in the case of configuring multiple trunks, the configuration according to the present invention described above may be extended to n.

As described above, the present invention can detect DTMF in the digital trunk of E1 or T1 so that signaling can be performed by directly connecting to a device using a different signaling method such as an optical transmission device, thereby eliminating an additional configuration. Can bring savings.

In addition, if the present invention is configured in a small device without conversion of conventional devices with respect to the IDLC method, transmission devices can be easily implemented in IDLC.

Claims (7)

A device for detecting D.M.F. in a digital trunk of an exchange, A line decoder for decoding channel data received in a time division multiplexing scheme; A multiplexer for sequentially selecting a plurality of channels constituting the channel data by using the decoded channel data by a counter value and outputting data of the selected channel; A counter for counting a clock using a synchronization signal determined by the time division multiplexing method as one cycle and outputting the counted count value; A latch unit for latching data output from the multiplexer to have a predetermined frequency and a duty cycle; A digital / analog converter for converting data latched by the latch unit into an analog form; A D.M.F receiver for detecting a D.M.F. from analog data converted by the digital / analog converter; A buffer for recording the detected D.F.F and the counter value output from the counter as a channel number when the D.M.F. is detected by the D.M.F. receiver; In the digital trunk characterized in that it comprises a central processing unit for periodically reading the D.M.F. and the channel number recorded in the buffer and converts the read D.M.F. and the channel number into signaling data. D.M.F detection device. The method of claim 1, D. M. F. detection apparatus for a digital trunk, characterized in that the cycle of the clock used in the counter determines that a plurality of channels used in the time division multiplexing scheme is selected within one period of the synchronization signal. The method of claim 1, When the same D.F.F is continuously detected at the D.F.F receiver, the same D.F.F detected after the first detected D.F.F is inserted into the buffer. And a control logic for controlling the D.M.F receiver to prevent recording. The method according to claim 1 or 3, D. M. F. detection device in a digital trunk, characterized in that the buffer has a first-in, first-out structure. A device for detecting D.M.F. in a digital trunk of an exchange, A first process of decoding channel data received in a time division multiplexing scheme; A second process of counting a clock using a synchronization signal determined by the time division multiplexing method as one cycle and outputting the counted count value as a channel number; A third process of outputting data of the channel selected by the channel number among the decoded channel data and latching the data to have a predetermined frequency and a duty cycle; Converting the latched data into an analog form and detecting a D.M.F. from the converted analog form data; A fifth process of recording the detected D.F. and the channel number when the D.F. is detected; And a sixth process of periodically reading the recorded D.M.F and channel number and converting the read D.M.F and channel number into signaling data. T.M.F Detection Method The digital trunk of claim 5, wherein the clock cycle used in the second process is determined such that a plurality of channels used in the time division multiplexing scheme are selected within one period of the synchronization signal. M. F detection method The method of claim 5, If the same D.F.F is continuously detected in the fourth process, the process of blocking the recording of the same D.F.F detected after the first detected D.F.F is further blocked. D.M.F detection method in a digital trunk characterized in that it comprises.

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