CN2186976Y - Portable general telephone fee counter - Google Patents

Abstract

A portable telephone charging device is composed of a single-chip microcomputer, including a key circuit, EPROM, E ² PROM, a power supply control circuit, a decoding display circuit, a telephone interface circuit including reverse polarity detection, and a ring-back tone detection circuit. Forced timing, reverse polarity detection and ring-back tone detection are connected to the single-chip microcomputer in parallel, and the priority is determined according to the above order. This telephone billing device adopts three kinds of timing control circuits to act on the single-chip microcomputer in parallel at the same time, which can ensure the accuracy and reliability of billing timing. It is suitable for various telephone line pulses, dual-tone multi-frequency compatible, low power consumption, and easy to use.

Description

The utility model relates to a billing device for the line used by the calling party in telephone communication.

At present, our country has developed a variety of telephone timing and billing devices. These billing devices can be divided into three types according to the detection method: ①Use the reverse polarity signal provided by the switch to start the billing device for timing. Such as CN2051422, CN2068738, CN2106457, CN1039691, etc. ②A billing device using ring-back tone as a basis, such as CN2052996, CN2045559, etc. ③Billing equipment for manually starting the timing circuit, such as CN2087407, CN2110322, etc. Since ordinary telephone lines cannot provide reverse polarity signals, the first type of billing equipment is limited to long-distance direct dial lines, but it has the advantage of being accurate, especially when making long-distance calls. The second type of billing equipment can be applied to ordinary telephones, but when in use, the ringback tone often appears abnormal, resulting in inaccurate billing such as miscalculation and miscalculation, so the accuracy and reliability of billing lower. For the third type, it does not belong to automatic billing. When there is no reverse polarity signal or abnormal ring back tone, accurate timing can be ensured manually.

The purpose of this utility model is to design a new type of portable general-purpose telephone charging device, which uses a low-power single-chip microcomputer as a microprocessor, and is provided with a circuit for detecting and processing the ring-back tone signal and the reverse polarity signal , and supplemented by the "strong meter" key, so as to ensure the accuracy and reliability of billing.

The utility model telephone billing device comprises a low-power single-chip microcomputer 1 and a power supply control circuit 2 connected with the single-chip microcomputer, EPROM3, ^E2PROM4 , a button circuit 5, a telephone interface circuit 6, a DTMF decoder 7, and a decoding display circuit 9. It is characterized in that it is provided with a ring-back tone detection circuit 8 connected with the single-chip microcomputer 1 and connected in series with the telephone line A or line B, and it includes:

a, a coupler, the ringback tone signal is coupled to the input of the input protection circuit;

b. An input protection circuit, which limits the amplitude of the input signal below 0.7V and outputs it to the zero-crossing comparator;

c. A zero-crossing comparator, which normalizes voltage input signals of different amplitudes into unipolar pulse signals of the same amplitude, and outputs them to the lock loop circuit;

d. A direction-locked loop circuit, which generates an effective low-level output for a unipolar pulse input signal of a certain fixed frequency band, and sends the output signal to a single-chip microcomputer for processing.

Another feature of the present utility model is, above-mentioned ring-back tone detection circuit 8, the telephone interface circuit 6 that contains reverse polarity detection function and the button circuit 5 that contains forced timing function are connected in parallel to the single-chip microcomputer, and by forced timing, reverse polarity detection, The order in which ringback tones are detected determines priority.

The utility model relates to a telephone charging device. Using advanced measurement methods, it can measure the call time of various telephone lines, and calculate the cost according to the call area. It is applicable to pulse and dual-tone multi-frequency telephones. The timing and billing are accurate and reliable, and the power consumption is extremely low. , easy to use.

Fig. 1 is a system block diagram of the utility model.

Fig. 2 is the electrical schematic diagram of the echo detection circuit of the present invention.

Fig. 3 is a schematic diagram of the connection of the E ² PROM of the present invention.

Fig. 4 is a block diagram of the utility model pulse burr processing program

Fig. 5 is the processing flow diagram of the utility model antipolar signal, ring back tone detection signal and manual start signal three.

Example:

See Figure 1. Box 1 is the central microprocessor, which adopts the low-consumption single-chip microcomputer 80CL31 produced by Philips. This kind of single-chip microcomputer can work under low power supply voltage and low operating frequency. The power consumption of the circuit is also low, and the working clock of MCS51 series MCU of Intel series shall not be lower than 1.2MHZ.

Box 2 is the power control circuit. It can complete the control of the circuit power supply. When the "Start" button is pressed, the DC power provided by the external power supply can be supplied to the working circuit; Cut off the external power supply from the internal circuit. The power control circuit itself is in a normally powered state, and its power consumption is extremely low.

Box 3 is EPROM, which stores execution code and area code table.

Box 4 is an electrically erasable read-only memory for storing the rate table, and the value therein can be modified through the telephone keys.

Box 5 is the button circuit. In the utility model, three function buttons of "start", "round check" and "strong meter" are adopted. The "start" button is used to "wake up" the circuit that has been in the state of reducing power consumption to enter the normal working state; press the "check" button to query the number, call duration and cost respectively; Forced timing is implemented when the signal and ringback tone are abnormal.

Box 6 is the telephone interface circuit for detecting the state of the telephone, including off-hook detection and reverse polarity detection. In the long-distance line that provides the reverse polarity signal, once the called party picks up the hook, the exchange will give the reverse polarity signal, and the single-chip microcomputer will start timing accordingly. When using a pulse telephone, each time a number is pressed, the telephone line is shown as continuous on and off, and the pick/hang detection port outputs a pulse string, and the number value can be obtained after the single-chip microcomputer processes it.

Box 7 is a DTMF decoding circuit, which can decode the DTMF signal sent by the DTMF phone into a telephone number value.

Box 8 is a ring-back tone detection circuit, which monitors whether there is a call signal with a frequency in the range of 400-500HZ in the telephone line, such as busy tone and ring-back, and if so, outputs an effective level for processing by the single-chip microcomputer.

Box 9 is an LCD liquid crystal display circuit for displaying various information. The utility model adopts a 6-character LCD, and its highest bit (the first bit) is used as a status prompt bit, such as "H" indicates a number; "P" indicates a price; " One" means time etc.

Referring to Figure 2, V1 and V2 are used to detect the unhook status, pulse number and polarity reversal signal. Connect S1 and S2 terminals in series to the A line or B line of the telephone line. When the current in the line is shown in Figure 2, U1 reflects the state of unhooking and hanging. When using pulse telephone dialing, the output of U1 is a series of pulses. The corresponding pulse number can be obtained by processing; U2 is used to detect the reverse polarity signal to start timing. The actual installation does not limit the polarity, as for which one of U1 and U2 detects the pulse and which one detects the reverse polarity signal, the single-chip microcomputer can make a judgment.

The transformer T in Figure 2 is an audio transformer. When there is a ringing signal in the circuit, the secondary induction signal of the audio transformer is enough to damage the chip. The protection circuit composed of D1 and D2 can limit the signal amplitude below 0.7V.

Because the strength of the ringback tone of the telephone varies greatly, exceeding the input signal variation range required by the detection circuit, in order to normalize the signal, a comparison circuit is used to pass the signals with different amplitudes through the zero-crossing comparator U3. It becomes a bipolar pulse signal with the same amplitude. This pulse becomes a unipolar pulse signal after passing through diode D3, R3 and R4, and then forms an input signal allowed by U5 after being divided by R3 and R4. U5 is a phase-locked loop circuit, when the frequency of the input signal falls into the frequency band determined by the resistive capacitor device in the circuit, an effective low level is generated at the output end. In the utility model, a 450HZ ringback signal that lasts for 2 seconds is detected. Once the ringback tone appears, the Generates an active low level at the output.

Figure 3 is a schematic diagram of the connection between the E ² PROM chip and the microcontroller. E ² PROM is an electrically erasable read-only memory, which is used to store toll rates. In order to reduce cost, reduce circuit power consumption and reduce volume, the utility model adopts CMOS serial E ² PROM. The chip is equipped with a boost and timing circuit. The circuit only needs to provide +5V power supply, and the value in the internal unit can be modified by the CPU issuing instructions and data. It overcomes the disadvantage that the rate of the current billing equipment is not easy to modify. The telephone rate in CNZO51422 and CN1039691 is fixed, and if you want to modify it, you must use EPROM writing equipment, and complete the modification of the rate separately outside the billing device; although CN2106457 provides an EPROM writing circuit, you still need to write the original EPROM Dial out and insert a new EPROM. When the device wants to modify the rate, it only needs to press the number "000", then input the long-distance area code (or list number) and then input the rate to complete the modification of the rate.

Figure 4 is a block diagram of pulse glitch processing. Due to the complexity of the telephone line signal, glitches often appear in the pulse signal, which affects the accuracy of number acquisition. In CN2051422, hardware circuits such as shaping, integration, and monostable are used to remove thorns. The utility model starts from reducing power consumption and volume, and adopts software to eliminate the impact of burrs. The basic idea is that the CPU regularly samples the output signal of the photoelectric tube. Then carry out statistical processing, the processing process is shown in Figure 4. Since the telephone pulse is relatively slow (pulse width > 10ms), narrow pulses with short duration can be considered as glitches. In Figure 4, C1 is the narrowest negative pulse width (the width is reflected by the number of sampling points), C2 is the narrowest positive pulse width, PO is the initial count value in the "0" state, and P1 is the initial count value in the "1" state.

Figure 5 reflects the relationship between the polarity reversal signal, the ring-back tone detection signal and the manual start signal. When the phone number is dialed, if the called party line is occupied, the switch will give a busy tone with an interval of 0.5 seconds (duration 0.5 seconds), if the called party line is idle, the switch will send 450HZ to the calling party for a duration of 0.5 seconds 1 second ringback tone, so if the 450HZ signal does not appear, the calling party and the called party cannot be connected, so the program first detects the 450HZ signal, and starts the timer (4 seconds) after it appears, and then detects the "manual" start The flag unit (set by the interrupt), if the "manual" start flag is valid, it will enter the timing state; if it is invalid, it will detect the reverse polarity flag, if the reverse polarity appears, it will enter the timing state; if the above two are invalid, you can start timing, If the ring back tone appears within 4 seconds, it means that the called party has not picked up the phone, and the 4-second timer must be reset, and the above process must be repeated; if the ring back tone disappears, it means that the called party has picked up the If busy tone is received, jump to the reset state and re-enter the number acquisition procedure.

Claims (2)

1. Portable universal telephone billing device, including a low-power single-chip microcomputer [1] and a power control circuit [2] connected to the single-chip microcomputer [1], EPROM [3], E ² PROM [4], key circuit [5] ], telephone interface circuit [6], DTMF decoder [7], LCD decoding display circuit [9]. It is characterized in that it is provided with a ring-back tone detection circuit [8] connected with the single-chip microcomputer [1] and connected in series with the telephone line A or line B, and it includes: a, a coupler, the ringback tone signal is coupled to the input of the input protection circuit; b. An input protection circuit that limits the amplitude of the input signal below 0.7 volts and outputs it to the zero-crossing comparator; c. A zero-crossing comparator, which normalizes the input voltage signals of different amplitudes into unipolar pulse signals with the same amplitude, and outputs them to the phase-locked loop circuit; d. A phase-locked loop circuit, which generates an effective low-level output for a fixed frequency band unipolar pulse input signal, and sends the output signal to a single-chip microcomputer. 2. The telephone billing device according to claim 1, characterized in that the ring-back tone detection circuit [8], the telephone interface [6] containing the reverse polarity detection circuit and the button circuit [5] containing the forced timing circuit Parallel access to single-chip microcomputer [1], and determine the priority in the order of forced timing, reverse polarity detection, and ring-back tone detection.

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