CN2251227Y

CN2251227Y - Anti-theft apparatus for telephone

Info

Publication number: CN2251227Y
Application number: CN 95214704
Authority: CN
Inventors: 姚连敏
Original assignee: BEIJING TELECOMMUNICATION DEVELOPMENT GENERAL Co
Current assignee: BEIJING TELECOMMUNICATION DEVELOPMENT GENERAL Co
Priority date: 1995-06-23
Filing date: 1995-06-23
Publication date: 1997-04-02
Anticipated expiration: 2005-06-23

Abstract

The utility model relates to a device connected in series between a telephone line and a telephone to prevent the telephone from embezzlement, which is composed of an embezzlement discriminating circuit and an interference source circuit which are connected together, wherein, the embezzlement discriminating circuit is an NOR logic circuit provided with time control, and the NOR logic circuit is formed by the connection of a voltage identifying circuit of the telephone line, and an identifying circuit for off-hook and on-hook. The NOR logic circuit supplies working power for the interference source circuit which comprises a 941 hz oscillator, an oscillator for 10 ms square waves, and a light indicating circuit which integrates outputs of the two oscillators and outputs interference current. When the line voltage is below 15V and a telephone subscriber does not pick up the telephone, the utility model can supply power for the interference source circuit which generates audio interference and limits dialing.

Description

The anti-device of usurping of phone

The utility model relates to the auxilliary feeder apparatus of a kind of phone, relates to a kind of device that prevents to usurp phone or rather.

Along with the development that phone is built, the phone installation amount is also growing, but is accompanied by the surge of subscriber phone, some has also taken place usurped the bad phenomenon of phone, makes the telephone subscriber suffer unnecessary economic loss.Switch on the telephone network can not be discerned and usurp phone, and promptly any position between the input from the switch port of export to subsets all can be inserted and usurp phone, and switch all can normally continue.

The purpose of this utility model is the anti-device of usurping of a kind of phone of design, device is at the subscriber phone pusher side, usurp phone in switch to the access of any position between telephone set, prevent that usurping device all can discern, showing and produce that interference tones makes it to converse can not normal dialing, and has and do not influence local network and detect and be convenient to the characteristic that the user is connected arbitrarily.

The anti-groundwork principle of usurping device of the utility model phone is that to utilize the internal resistance of power supply for exchange circuit (comprising line resistance) be load, has the disturbance current that makes the load upper reaches cross artificial generation when usurping to form interference signal, reaches the purpose that destruction is usurped.

Phone of the present utility model is anti-usurps device, is serially connected between outside line and telephone set, by usurping discriminator circuit and the interference source circuit connects and composes, it is characterized in that:

The described discriminator circuit of usurping is the NOR logic circuit of being controlled by telephone line voltage identification circuit and the band time of plucking, the on-hook identification circuit connects and composes, and NOR logic circuit output connects the power end of interference source circuit; Described interference source circuit comprises the oscillator that produces the 941HZ frequency, produce the oscillator of 10mS square wave, the amplifier that the output of two oscillators is united two into one, exports interrupted square ripple signal with is connected, produces the transistor driver of disturbance current and light demonstration with amplifier output.

Described telephone line voltage identification circuit is by diode bridge, resistance R 1, R2, and transistor BG1,15V voltage stabilizing didoe DW1 connect and compose; Describedly pluck, the on-hook identification circuit is forward and reverse by two and photoelectrical coupler that connect constitutes; The NOR logic circuit of described band time control is by transistor BG2, BG3, BG4, resistance R 3, R4, R5, R6, R7, R22, and capacitor C 1, C2 connect and compose; The outside line of answering the call respectively of diode bridge input, the diode bridge output plus terminal also meets R1, R2, C2, R5 one end and BG2 collector electrode, the BG4 emitter, the R1 other end connects the BG1 base stage by DW1, the R2 other end also connects the BG1 collector electrode, C1 one end and the BG2 collection utmost point, the BG2 emitter also connects R4 one end and R3 one end, the R4 other end also connects the collector electrode of R22 one end and described two photoelectrical couplers, another termination of R22 BG3 base stage, the BG3 collector electrode also connects the C2 other end, the R5 other end and R6 one end, another termination of R6 BG4 base stage, the BG4 collector electrode connects R7 one end and connects the power positive end of described interference source circuit, diode bridge output negative terminal also connects the BG1 emitter, the C1 other end, the R3 other end, the BG3 emitter, the R7 other end, the emitter of the power supply negative terminal of interference source circuit and described two photoelectrical couplers, described two photoelectrical couplers two inputs forward and reverse and that connect answer the call respectively line one end and telephone set one end, the telephone wire other end is connected with the telephone set other end.

The transistor driver of described interference source circuit is by diode D1, resistance R 20, R21, LED and transistor BG5 connect and compose, the D1 positive pole connects described amplifier out, the D1 negative pole connects the BG5 base stage by R21, and the BG5 collector electrode connects interference source circuit power anode by LED and R20, and the BG5 emitter connects the power supply negative terminal of interference source circuit.

When substation off-hook but telephone line voltage is lower than 15V not, when promptly the someone usurps phone, the telephone line voltage identification circuit provides supply voltage with the NOR logic circuit of plucking, the on-hook identification circuit connects and composes to the interference source circuit, make it to produce alarm signal and disturbance current and be delivered on the telephone line, destruction is usurped.

Further specify technology of the present utility model below in conjunction with the embodiment accompanying drawing:

Fig. 1 is the anti-device theory diagram of usurping of phone;

Fig. 2 is the anti-device circuit diagram of usurping of phone;

Fig. 3 is the anti-device time control waveform figure that usurps of phone.

Referring to Fig. 1, phone is anti-usurps device by line voltage distribution identification circuit 11, dislodging machine identification circuit 12, and the band time NOR logic circuit 13 and the interference source circuit 14 of control connects and composes, wherein L1, L2 connect subscriber's telephone line, and 11, l2 connects substation 11,12,13 and constitute and usurp discriminator circuit.When line voltage distribution is higher than 15V, substation off-hook or not during off-hook, NOR logic circuit 13 outputs are 0V substantially; When line voltage distribution is lower than 15V, during the substation off-hook, NOR logic circuit 13 outputs also are 0V substantially; Have only the line voltage distribution of working as to be lower than 15V, during off-hook, NOR logic circuit 13 output supply voltages do not provide working power to interference source circuit 14 to substation, interference source circuit 14 is exported disturbance currents 1 and is delivered to telephone wire L1 by line voltage distribution identification circuit 11, on the L2.

Referring to Fig. 2, diode bridge B1,15V voltage stabilizing didoe DW1, transistor BG1 constitute the line voltage distribution identification circuit.Two photoelectrical coupler TLP521-1, TLP521-2 is forward and reverse and connect formation dislodging machine identification circuit, but test subscriber's phone has no current to pass through, when the substation off-hook has electric current to pass through, its triode portion also has collector current to pass through, can be with the input signal short circuit of BG3, and control BG4 ends.Transistor BG2, BG3, BG4 and peripheral cell thereof are finished the NOR-logic function to line voltage distribution identification signal and dislodging machine identification signal.

During no off-hook, line voltage distribution is higher than 15V, and line voltage distribution was lower than 15V when off-hook was arranged.When line voltage distribution is higher than 15V, substation not during off-hook, the BG1 conducting, BG2, BG3, BG4 all end, and the BG4 current collection is 0V very; When line voltage distribution is higher than 15V, substation off-hook, the BG1 conducting, BG2, BG3,8G4 all end, and the BG4 current collection is 0V very; When line voltage distribution was lower than 15V, substation off-hook, BG1 ended, the BG2 conducting, and BG3, BG4 all ends, and the BG4 current collection is 0V very; When line voltage distribution is lower than 15V, the user is (usurping state) during off-hook not, and BG1 ends, BG2, BG3, the equal conducting of BG4, and BG4 collector electrode output supply voltage is promptly through the line voltage distribution of diode bridge B1 output, to the interference source circuit supply.

The interference source circuit is made up of two oscillators and interlock circuit, for restraining the dialing of dual-tone multifrequency, sends the interference signal based on 941HZ during warning, and it is correct having only #, 0, * during button, and other buttons are all disturbed.Adopt a slice LM342 to be connected into interference source during enforcement, wherein LM342-3 is used to produce the square wave of 10MS, LM342-2 is used to produce the 941HZ square wave, LM342-1 is used for signal with two oscillators output two combine into one producing interrupted square ripple signal, and this signal promotes BG5 and produces disturbance current and light shows signal LED.

When line voltage distribution is higher than 15V or substation off-hook, this interference source circuit does not produce interference signal, only when line voltage distribution is lower than 15V and substation picking machine because of BG4 ends no working power, this interference source circuit has working power because of the BG4 conducting, produces interference signal.

Referring to Fig. 3 this anti-usurp device be satisfy that on-line testing is not reported to the police, double-tone frequently and the different requirements of pulse limited dialing, in time control, done as shown in the figure by row, t is a time shaft among the figure, V is the line electricity last item.Do not report to the police during the t1 ceases to be busy, monitor to have or not at any time and usurp phenomenon; The t2 on-line testing is not reported to the police, it is to use for the normal detection that guarantees Local Exchange time of delay that t2 is set, need to report to the police after time of delay at t2 even there is the people to usurp also in this time, t2 determines in the charging interval by R2 among Fig. 2 (6.2M) and C1 (0.1 μ f) again.When the low BG1 electric current of voltage drop on the circuit suddenly and when disconnected, BG1 collector potential (being the BG3 base potential) can not be set up at once, could supply with the interference source circuit power after waiting C1 charging certain hour.The t3 time is alarm time, the restriction dual-tone dialing.The pulse dialing of t4 time restriction.This time is by e by BG4 of the stored charge of capacitor C 2 (0.47 μ f), the discharge decision of b loop, interference source works in time of delay, still be equivalent to the phone talking state this moment, and line voltage distribution can not be risen, and appropriator is if use the dialing of pulse phone then to be restrained.

The anti-device of usurping of phone of the present utility model, behind the access local network, owing to set up time control circuit, thus do not hinder the normal detection of local network, can be in ring, ceases to be busy, operate as normal under the various situations such as conversation; The anti-device of usurping is except that producing audio disturbances and limit appropriator and no matter use which kind of phone all can not dial; Photoelectric coupled device identification is plucked, on-hook owing to set up, and can make things convenient for terminal block, makes the user can connect nonpolarity restriction arbitrarily.

Claims

1, a kind of phone is anti-usurps device, is serially connected between outside line and telephone set, by usurping discriminator circuit and the interference source circuit connects and composes, it is characterized in that:

2, phone according to claim 1 is anti-usurps device, it is characterized in that: described telephone line voltage identification circuit is by diode bridge, resistance R 1, R2, and transistor BG1,15V voltage stabilizing didoe DW1 connect and compose; Describedly pluck, the on-hook identification circuit is forward and reverse by two and photoelectrical coupler that connect constitutes; The NOR logic circuit of described band time control is by transistor BG2, BG3,8G4, resistance R 3, R4, R5, R6, R7, R22, and capacitor C 1, C2 connect and compose; The outside line of answering the call respectively of diode bridge input, the diode bridge output plus terminal also meets R1, R2, C2, R5 one end and BG2 collector electrode, the BG4 emitter, the R1 other end connects the BG1 base stage by DW1, the R2 other end also connects the BG1 collector electrode, C1 one end and the BG2 collection utmost point, the BG2 emitter also connects R4 one end and R3 one end, the R4 other end also connects the collector electrode of R22 one end and described two photoelectrical couplers, another termination of R22 BG3 base stage, the BG3 collector electrode also connects the C2 other end, the R5 other end and R6 one end, another termination of R6 BG4 base stage, the BG4 collector electrode connects R7 one end and connects the power positive end of described interference source circuit, diode bridge output negative terminal also connects the BG1 emitter, the C1 other end, the R3 other end, the BG3 emitter, the R7 other end, the emitter of the power supply negative terminal of interference source circuit and described two photoelectrical couplers, described two photoelectrical couplers two inputs forward and reverse and that connect answer the call respectively line one end and telephone set one end, the telephone wire other end is connected with the telephone set other end.

3, the anti-device of usurping of phone according to claim 1, it is characterized in that: the transistor driver of described interference source circuit is by diode D1, resistance R 20, R21, LED and transistor BG5 connect and compose, and the D1 positive pole connects described amplifier out, and the D1 negative pole connects the BG5 base stage by R21, the BG5 collector electrode connects interference source circuit power anode by LED and R20, and the BG5 emitter connects the power supply negative terminal of interference source circuit.