KR950001240Y1 - Circuit for detecting call charges - Google Patents

Abstract

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Description

Charge signal detection circuit for voltage inversion / tone system of exchange using public telephone line

1 is a conventional charging signal detection circuit and block diagram.

2 is a diagram showing input and output waveforms of the charging signal according to the voltage inversion method.

3 is a charging signal detection circuit and block diagram according to the present invention.

4 is a third input / output waveform diagram of a charging signal according to a tone method.

* Explanation of symbols for main parts of the drawings

40: voltage inversion signal detector 50: tone detector

51: high pass filter (HPF) 52: clamping circuit

53: frequency control circuit 54: PLL (Phase Locked Loop) IC

55: low pass filter (LPF)

The present invention relates to a device for detecting a Call Metering Pulse in a telephone using a Public Switching Telephone Network (PSTN). In particular, the Line Reverse and Tone signals can be detected simultaneously. The present invention relates to an apparatus for detecting charging signals of public telephone lines.

The conventional method of detecting the metering pulse is a line reverse method, that is, a method in which the polarity of the tip and the ring of the telephone line is reversed at regular intervals, and is known as a public switching telephone network (PSTN). The detection circuit for detecting the charging signal, i.e., the voltage reversal signal, of the public telephone which is connected to is used as the ringer unit 10 and the ringer unit connected to the tip and ring terminals as shown in FIG. 10) is composed of a dial transmitter 20, a telephone circuit unit 30 and a voltage inversion signal detection unit 40 connected via a switch (SW1), wherein the voltage inversion signal detection unit 40 of the tip and ring Photo coupler PC1 (PC2) for obtaining pulse at voltage inversion, diodes D1-D6 for operating the port coupler PC1 (PC2) irrespective of the polarity of the tip and ring, and the photocoupler ( Current limiting resistor (R2) and output of light-emitting part of PC1) (PC2) Unit consists of a load resistor (R1) (R3).

As shown in FIG. 2, when the charging signal (the voltage inversion part of the tip and ring) is generated by t as shown in FIG. 2, the output of the photocoupler PC1 is output from the voltage inversion signal detector 40. The state of (a) and the output (b) of the photocoupler (PC2) are changed from the initial state by the time when the charging signal (t) occurs, and when the charging signal ends again, the state is restored to the initial state and the photocoupler (PC1) is returned. Since one pulse is generated at the output of PC2, the voltage inversion signal detector 40 detects one charging signal.

However, since the charging signal detection method by the conventional voltage inversion detection method is used only in the voltage method, it is adapted to the tone (TONE) method (generated charge signal method using a specific tone of 12KHZ or 16KHZ) to generate a specific frequency. I couldn't use it.

Therefore, the present invention has been devised to improve the above-mentioned problems. In particular, a voltage inversion method and a specific frequency in which a charging pulse generated from an exchanger to be provided to a terminal causes the voltage of the chip ring to be inverted at a constant cycle. (12KHZ or 16KHZ) generating a charging signal detection circuit comprising a voltage inversion signal detection unit and a tone detection unit to adapt to the tone method used to generate and will be described in detail by the accompanying drawings as follows.

That is, as shown in FIG. 3, the ringer 10 connected to the tip and the ring terminal, the voltage inversion signal detector 40 and the dial transmitter 20 connected to the ringer 10 through the switch SW1. And the call circuit unit 30 is provided in a conventional configuration, and in the present invention, the tone detection unit 50 for detecting a specific frequency and outputting a tone signal is added to the voltage inversion signal detection unit 40 in parallel. The tone detection unit 50 comprises a high frequency filter 51 (HPF) consisting of a capacitor (C1), a transformer (T1), and a resistor (R4) (R5) at an input terminal, and the high frequency filter (HPF). The clamping circuit 52 which becomes the diodes D7 (D8) and the condenser C2 at the rear stage of the signal is detected, and the specific frequency of the signal input from the rear end of the clamping circuit 52 is detected to set the frequency of the preset tone (the charging signal). PLL (Phase Locked Loop) IC 54, which compares with 12KHZ or 16KHZ and outputs a logic value when matched, and this PLL IC 54 A frequency regulating circuit 53 comprising a variable resistor VR1 and a condenser C3 for adjusting the reference set frequency, and a transformer T2 and a condenser C5 so that the tone signal does not interfere with the call circuit. It consists of a low pass filter 55 (LPF).

The operation and effects of the present invention made as described above are as follows. First, when the charging signal ("a" in FIG. 2) is generated by the voltage inversion method and enters the tip and the ring terminals, the voltage inversion signal detector 40 detects the photocoupler PC1 ( The charging signal is detected through the output terminal of PC2), and the charging signal (12KHZ or 16KHZ as shown in FIG. 4A) of the tone method is generated at the exchanger, and thus the tip (TIP) and the ring ( RING) is inserted into the terminal of the present invention, the tone detection unit 50 of the present invention passes through the high-temperature filter 51 consisting of the capacitor (C1), transformer (T1) and resistor (R4) (R5) and clamping circuit 52 of the subsequent stage The PLL IC 54 is inputted to the PLL IC 54 through the capacitor C2 with the excess input signal blocked. The PLL IC 54 finds a specific frequency in the input tone signal, and the variable resistor VR1 is a peripheral circuit thereof. ) And tone when matched against the preset reference frequency (12KHZ or 16KHZ) set by capacitor C3 As long as the signal is input (t1), the logic value is output through the output resistor R6 of the output terminal to detect the tone signal as shown in FIG. 4B.

As described in detail above, the present invention is configured by adding a tone detection unit for detecting a charging signal made of a tone method to a circuit for detecting a charging signal made of a voltage inversion method, so that the charging signal method made of a voltage inversion method or a tone method This has the effect of making everything available.

Claims (2)

In the charging signal detection circuit provided with the voltage inversion signal detection unit 40 for detecting the charging signal of the voltage inversion method, a tone for detecting the charging signal of the tone method using a specific frequency in the charging signal detection circuit. Voltage inversion / tone system combined charging signal detection circuit of a switch using a public telephone line, characterized in that it comprises a detection unit (50). 2. The tone detector 50 of claim 1, wherein the tone detector 50 detects a specific frequency of the input signal passing through the clamping circuit and the high pass filter 51 and the clamping circuit 52 of the input stage for blocking the excessive input and compares it with a preset frequency. And a PLL IC (54) for outputting a logic value and a frequency control circuit (53) surrounding the PLL IC.