KR970001910B1 - Tone detecting circuits for voice response system - Google Patents

Abstract

A tone detection circuit of a voice mailing system is provided, which includes a low pass filter (20) for filtering a calling signal input from the interface circuit part (10) to output, a tone frequency detecting member (30) for providing a valid/non-valid frequency detection signal according to whether the tone frequency is detected for a predetermined time period with relation to the calling signal output from the low pass filter (20), a tone cadence detecting member (40) for providing a valid/non-valid cadence detection signal according to whether the cadence state is detected or not in the calling signal output from the low pass filter (20), a tone validity state detecting member (50) for output a tone validity detection signal by logic arithmetic of the valid/non-valid frequency detection signal and the valid/non valid cadence detection signal, and a control member (60) for controlling calling loop of the interface part, wherein the calling state which is transmitted from the switch board is precisely detected, for thereby improving the speech quality of the voice mailing system.

Description

Tone Detection Circuit and Method in Voice Mail System

1 shows waveforms and cadences of frequencies of tone signals.

2 is a tone detection circuit diagram of the present invention in a voice mail system.

3 is a waveform diagram of each circuit part according to FIG. 2;

The present invention relates to a tone detection circuit and method, and more particularly, to a tone detection circuit and method for detecting a call signal transmitted from a switchboard to a voice mail system (VMS) to control a call loop.

In the current voice mail system, the line connection with the exchange is performed by a loop start method. When the other party hooks on during the voice service in the voice mail system (VMS), the exchange does not inform the voice mail system whether it is hooked on. This is because the voice mail system adopts the loop start method.

In the voice mail system, a method of turning off a call loop is to turn off the call loop by detecting a busy tone input through a line at the tone detector. Even when voice is transmitted and recorded in the voice mail system, the voice includes busy tone. The commercially available tone detector detects even busy tone included in the voice component when the voice is transmitted or recorded. .

Accordingly, the voice mail system may turn off the call loop during the call service between the subscriber and the voice mail system, that is, during voice transmission or recording, thereby degrading the call quality of the voice service.

Accordingly, an object of the present invention is to provide a tone detection circuit and method for accurately detecting a call state transmitted from an exchange in a voice mail system to improve the call service of the voice mail system.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings. The present invention performs cadence and frequency detection of a tone signal so that busy tone is not detected during voice (music) transmission or recording in a voice mail system. Therefore, if both the cadence detection data and the frequency detection data are valid data set in advance, the call loop is blocked by recognizing the tone signal.

FIG. 1 is a waveform diagram showing tone frequency and candence, and shows Dial Tone, Busy Tone, Ring Back Tone, and Reorder Tone, respectively. .

The tone frequency and cadence are shown in Table (1).

2 is a block diagram of a tone detection circuit applied to the present invention in a voice mail system, which is input to the voice mail system interface circuit 10 and the voice mail system interface 10 connected to an exchange to perform a voice service. The low pass filter unit 20, which locally filters the DTMF signal, passes the tone signal component, and detects the frequency of the tone signal component output from the low pass filter unit 20. A frequency detector 30 that outputs a VAFS, and a cadence detector 40 that detects the cadence of the band signal filtered by the band detector by the frequency detector 30 and outputs an effective cadence signal VACS if it is a cadence of the preset tone signal. ) And the effective frequency signal VAFS and the valid cadence signal VVAC are output from the frequency detector 30 and the cadence detector 40. Gate line 50 for outputting effective tone data VTND by a call and controlling the line interface of the interface circuit unit 10 of the voice mail system in response to output of the effective tone data VTND from the gate unit 50; The line interface control unit 60 is configured.

The voice mail system interface circuit unit 10 includes a line interface unit, a hybrid circuit unit, and a codec. Since the operation of forming a call of the voice mail system is generally known, a detailed operation description of the interface circuit unit 10 is described. Omit.

The line interface controller 60 according to the embodiment of the present invention includes a CPU 62, a memory unit 64, a programmable array logic (PAL) decoder 66, a clock generator 68, and a ring detector 70. It consists of. The ring detection unit 70 is output from the exchanger and detects a ring signal at the tip T and ring R stages and transmits the ring signal to the CPU 62. The memory unit 64 stores information output from the frequency detector 30 and the cadence detector 40 through the address buffer ABS and the data bus DBS under the control of the CPU 62. The CPU 62 controls the array of columns and rows of the PAL decoder 66 by inputting the effective tone data VTND output from the gate section 50, so that a predetermined signal from the PAL decoder 66, that is, an enable signal EN ), The clear signal CLR and the buffer enable signal BEN are output to control the frequency detector 30, the cadence detector 40, and the gate 50. The gate unit 50 receives an AND gate 52 connected to an effective frequency signal output line of the frequency detector 30 and an effective cadence signal output line of the cadence detector 40, and a signal output from the AND gate 52. 62 controls the first buffer 54 gated in response to the buffer enable signal BEN output through the PAL decoder 66, and the valid cadence signal VVAC output from the cadence detector 40. The second buffer 56 is gated in response to the buffer enable signal BEN.

In the voice (music) transmission or recording state from the exchange, a signal having a busy tone component is input to the voice mail system interface circuit unit 10, or the busy tone due to the hook-on state of the subscriber from the exchange is transmitted to the voice mail system circuit unit 10. ) Is entered. In the low pass filter unit 20 connected to the output line of the hybrid circuit unit in the voice mail system interface circuit unit 10, the signal having the non-tone component is low-pass filtered. The low pass filter 20 filters only frequencies of 1 KHz or less and is output to the frequency detector 30. The frequency detector 30 outputs the effective frequency signal VAFS in a logic high state after a predetermined time, for example, 2.27 sec, when the filtered signal is a tone signal.

FIG. 3A is a waveform diagram when an input signal is a tone signal, and FIG. 3B is a waveform diagram of an effective frequency signal VAFS output from the frequency detector 30. The tone signal is a dial tone, busy tone, ringback tone, rearder tone, and the like shown in FIG.

In addition, the frequency detector 30 has a built-in band pass filter, and band-pass filters the low-pass filtered signal from the low pass filter 20 as a band pass filter and outputs it to the analog output terminal ALOGO. The bandpass filtered signal is output from the analog output terminal ALGO of the frequency detector 30 and input to the input terminal LIN of the cadence detector 40 through a low pass filtering element.

The cadence detector 40 detects the cadence of the input signal and outputs the valid cadence signal VAFS to the output terminal DET when the valid cadence is set in advance. If the signal input here is the tone signal in the cadence state shown in Fig. 1 and Table 1, an effective cadence signal VAFS is output.

The CPU 62 interrupts the frequency detector 30 at a predetermined period, for example, 50 msec. When the effective frequency signal VAFS is in a logic high state, the CPU 62 transmits the buffer enable signal BEN to the first buffer through the PAL decoder 66. 54) and the second buffer 56. Accordingly, the first buffer 54 and the second buffer 56 are enabled. When the gate unit 50 is the effective frequency signal VAFS of the frequency detector 30 and the effective cadence signal VACS of the cadence detector 40, the effective tone data is passed through the AND gate 52 and the first buffer 54. (VIND) is output to the CPU 62.

The CPU 62 detects the effective cadence signal VACS of the cadence detector 40 several times at a predetermined period, for example, 50 msec period, through the second buffer 56. When the valid cadence signal VVAC is output from the cadence detector 40, the CPU 62 recognizes the valid tone signal and controls the PAL decoder 66 to output the enable signal EN to the frequency detector 30. do. 3D shows the enable signal EN output from the PAL decoder 66. As shown in FIG.

The frequency detector 30 outputs the data Date to the data signal output terminals D0-D2 during the enable state EN. 3E is a waveform diagram of the data Date output from the frequency detector 30.

Accordingly, the CPU 62 recognizes the data Date as valid tone data VTND and turns off the line interface of the voice mail system interface circuit 10. After reading the effective tone data VTND, the CPU 62 clears the frequency detector 30 within a predetermined time (for example, several msec) to continuously detect the tone of the signal input to the frequency detector 30. To be able. That is, the CPU 62 outputs the clear signal CLR to the frequency detector 30 through the PAL decoder 66.

On the other hand, if the signal detected by the frequency detector 30 through the low pass filter 20 is interrupted by the CPU 62 at a predetermined period, for example, 50 msec, and is not detected as a valid tone signal, the CPU 62 decodes the PAL decoder. The frequency detector 30 is cleared within 2.8 sec through 66. 3C is a waveform diagram of a clear signal CLR output to the frequency detector 30 through the PAL decoder 60. Referring to FIG.

When the valid frequency signal VAFS and the valid cadence signal VACS are input from the gate unit 50, predetermined bits representing the state of the valid tone data VTND are set and output to the CPU 62. Therefore, since the frequency and cadence of tone signals such as busy tone, dial tone, reorder tone, and ring back tone do not coincide, the voice state of the voice (music) component is input to the voice mail system. Does not block the call loop.

As described above, the present invention detects the tone signal as the frequency and cadence detection of the signal input to the voice mail system, thereby preventing the call loop from being blocked during voice transmission or recording. Therefore, the present invention has an advantage of improving a call service by accurately detecting a call state transmitted from an exchange in a voice mail system.

Claims (7)

A tone detection circuit of a voice mail system, comprising: a low pass filter for low pass filtering and outputting a call signal input through a voice mail system interface circuit, and a preset time interval detection corresponding to a tone frequency for the low pass filtered call signal; Tone frequency detection means for outputting an invalid frequency detection signal according to the presence and absence, and the invalid cadence detection signal according to the presence or absence of the tone cadence state detection in the call signal bandpass filtered through the band pass filter included in the tone frequency detection means Tone cadence detection means for outputting, Tone detection invalid state detection means for outputting a tone invalid detection signal indicating a tone detection invalid state by performing a logical operation on the invalid frequency detection signal and the invalid cadence detection signal, and the tone The voice is caused by the tone invalid detection signal of the detection invalid state detection means. Tone detection circuit characterized in that it consists of a control means for controlling a call loop of the system side interface circuitry. The tone detection circuit of claim 1, wherein the low pass filter is a low pass filter for filtering a frequency band of 1 KHz or less. 3. The apparatus of claim 2, wherein the tone detection invalid state detection means comprises: a first gate portion for performing a logic operation on the invalid frequency detection signal of the tone frequency detection means and the invalid cadence detection signal of the tone cadence detection means; A second gate portion for operating the output signal of the first gate portion under control of the control means and a third gate portion for operating the invalid cadence detection signal of the tone cadence detection means in accordance with a control signal of the control means. Tone detection circuit, characterized in that the configuration. The apparatus of claim 3, wherein the control means controls the tone frequency detecting means and the tone cadence detecting means by signals output from the second gate portion and the third gate portion, and controls the call loop. And memory means for storing tone data of the tone frequency detecting means under control of the central processing unit. 5. The apparatus of claim 4, further comprising control line selecting means for selectively connecting predetermined control lines of said tone frequency detecting means and control lines of said second and third gate portions by row and column control of said central processing unit. Tone detection circuit. In the tone detection circuit of a voice mail system, the voice signal input through the voice mail system interface circuit unit has a low pass filter for filtering into a frequency band of 1 kHz or less, and frequency is effective when the tone signal frequency is detected in the low pass filtered call signal. A tone frequency detector for outputting a detection signal, a tone cadence detector for outputting a cadence valid detection signal when a cadence corresponding to a tone signal is detected in a bandpass filtered call signal by the tone frequency detector, the frequency valid detection signal and the A first gate portion for performing a logic operation on the cadence valid detection signal, a first latch for latching an output signal of the first gate portion by a predetermined control signal, and the cadence valid detection signal of the tone cadence detector; A second latch latched by a control signal, and the first and second latches Interrupt by a predetermined period by detecting a valid tone data of the tone signal detection circuit characterized in that it consists of a control unit for controlling a call loop of the voice mail system interface circuit. A tone detection method of a tone detection circuit in a voice mail system connected to an exchange, comprising: a first step of low-pass filtering and outputting a call signal input from the exchange to an interface of a voice mail system; and low-pass filtering in the first step A second process of detecting a frequency and a cadence of the transmitted call signal, a third process of outputting valid data when the frequency and the cadence of the call signal coincide with a preset frequency and cadence; and the voice mail system based on the valid data. Tone detection method comprising the fourth step of controlling the communication line of the interface unit.