CN2241954Y

CN2241954Y - Telephone set with function of disconnection alarming and preventing eavesdropping and preventing unauthorised calling

Info

Publication number: CN2241954Y
Application number: CN 95246140
Authority: CN
Inventors: 陈国强
Original assignee: Individual
Current assignee: Individual
Priority date: 1995-10-23
Filing date: 1995-10-23
Publication date: 1996-12-04
Anticipated expiration: 2005-10-23

Abstract

The utility model relates to a telephone set with function of disconnection alarming and preventing eavesdropping and preventing unauthorised calling, which is realized by adding a line voltage detection unit 1, an off hook switch unit 2, an interference source oscillating circuit unit 3, an accident alarming unit 4, etc. on the basis of a telephone set unit 5. The telephone set with function of disconnection alarming and preventing eavesdropping and preventing unauthorised calling has the characteristics of simple structure, and low cost, and has the characteristic of efficiently preventing the telephone line being embezzled or tapped by other people, alarming on time when the communication line generates the disconnection, and simultaneously enhancing the input impedance but lowering the line loss. The telephone line can be randomly accessed without the difference of the positive polarity and the negative polarity. The performance parameter of the telephone set with function of disconnection alarming and preventing eavesdropping and preventing unauthorised calling completely meets the network accessing requirement of the Ministry of Posts and Tele Communication.

Description

Have break alarm and anti-usurp, the telephone set of anti-eavesdrop function

The utility model relates to wire communication, control and micro-computer technology field automatically, more specifically to a kind of have break alarm and anti-usurp, the telephone set of anti-eavesdrop function.

Current phone is gradually popularized, and the dirty pool appearance of usurping other people telephone line conversation is constantly arranged thereupon, is usurped by the people for preventing telephone line, has occurred multiple burglar alarm on the market.But still have indivedual unprincipled fellows to adopt more abominable means to carry out circuit and usurp activity, be about to victim's telephone line and cut off, make burglar alarm ineffective, thereby realize that it usurps the purpose of circuit.And the telephone anti-theft device that generally uses at present prevents that only other people from usurping circuit and beating steathily.Steal when beating after appropriator cuts off victim's telephone line, telephone anti-theft device just loses the warning effect.And for example, in the disclosed device of Chinese patent ZL932453228, because phone on-hook input impedance is lower, hook state quiescent current big (actual measurement is more than 10 μ A), the telephone terminal network access that can not satisfy Ministry of Posts and Telecommunications's promulgation in 93 years replenish and require (require telephone terminal hook state quiescent current should less than 5 μ A).And the described device of above-mentioned patent in use, and there is polar requirement at exchange line A1, A2 two ends, and polarity connects the inverse time anti-theft device and can not work, and gives to install and use and make troubles.On the other hand, the line drop that sample circuit produces 2.4V when conversation of this device, this line drop belongs to unnecessary consumption for the off-hook voltage of 8-10 volt, is unfavorable for conversation.

Task of the present utility model and purpose provide a kind of have break alarm and anti-usurping, the telephone set of anti-eavesdrop function, this telephone set is to install control circuit additional to realize preventing that telephone line from being usurped and eavesdropping by other people on existing electronic telephone typical circuit basis, and when opening circuit, communication line can in time report to the police by the warning circuit of being adorned in the machine, specifically, the break alarm that has that the utility model provides reaches anti-usurping, the telephone set of anti-eavesdrop function, when appropriator inserted the conversation of free call on sb. else's expense through illegal means phone or cut off two kinds of situations generations of victim's phone circuit, the utility model all can send warning.In time tell the victim, very accident appears in this electromechanics words circuit, so that take precautions against processing.

Task of the present utility model and purpose provide a kind of have break alarm and anti-usurp, the telephone set of anti-eavesdrop function, this telephone set when connecing local line, nonpolarity requirement, and input impedance is bigger during on-hook, line loss is reduced greatly, meet the requirement of the national Ministry of Posts and Telecommunications fully.

For achieving the above object, the utility model has adopted several parts such as line voltage distribution testing circuit, off-hook switching circuit, interference source oscillating circuit, accident alarming circuit, power backup circuit and phone circuit to form.Specifically, the utlity model has break alarm and anti-usurp, the telephone set of anti-eavesdrop function comprises general phone circuit unit 5, the interference source oscillation circuit unit 3 of the line voltage distribution detecting unit 1 that is connected with the exchange line terminals respectively and off-hook switch element 2, input connection line voltage detection unit 1 output, input and output all are connected with described interference source oscillation circuit unit 3 accident alarming unit 4, described general phone circuit unit 5 also is connected with off-hook switching circuit unit 2 with described interference source oscillation circuit unit 3.

According to the utility model provide have break alarm and anti-usurp, the telephone set of anti-eavesdrop function, it is characterized in that described off-hook switching circuit unit 2 mainly is made of rectifier bridge heap BR2 and optical coupler O1.

According to the utility model provide have break alarm and anti-usurp, the telephone set of anti-eavesdrop function, it is characterized in that, described line voltage distribution detecting unit 1 comprises transistor T R2, TR3, TR4, constitutes the Zener diode ZD1 of family of power and influence's level sensitive circuit with transistor T R2, wherein the cascaded switch circuit of transistor T R3 and TR4 formation is used to open and close the interference source oscillating circuit.

According to the utility model provide have break alarm and anti-usurp, the telephone set of anti-eavesdrop function, it is characterized in that, described interference source oscillation circuit unit 3 constitutes the positive feedback oscillator by four NAND gate, one road output signal is sent into telephone line, and another road output signal is delivered to accident alarming circuit unit 4 by resistance R 4.

According to the utility model provide have break alarm and anti-usurp, the telephone set of anti-eavesdrop function, it is characterized in that, described accident alarming circuit unit 4 can be the alarm of various ways, even, start security system or put through alarm call by relay or photoelectrical coupler control secondary circuit.

According to the utility model provide have break alarm and anti-usurp, the telephone set of anti-eavesdrop function, it is characterized in that described accident alarming circuit unit 4 can be to constitute sound, light alarm mechanism by buzzer B1 and light-emitting diode D1.

According to the utility model provide have break alarm and anti-usurp, the telephone set of anti-eavesdrop function, it is characterized in that also comprise a back-up source unit 6, it comprises battery and isolating diode D2.

Of the present utility model have break alarm and anti-usurp, the telephone set of anti-eavesdrop function is to add to report to the police and countermeasure set forms on the typical circuit basis of universal electric telephone set, so enforcement the utility model, have following characteristics: simple in structure, with low cost, can prevent effectively that telephone line from being usurped or eavesdropping by other people, and in time report to the police when broken string appearred in communication line, improved input impedance simultaneously and reduced line loss, and can be regardless of positive negative ground and insert telephone line arbitrarily.

In conjunction with the accompanying drawings and embodiments, further specify characteristics of the present utility model, in the accompanying drawing:

Fig. 1 be of the present utility model have break alarm and anti-usurp, the telephone set block diagram of anti-eavesdrop function;

Fig. 2 be of the present utility model have break alarm and anti-usurp, the circuit theory diagrams of the telephone set embodiment of anti-eavesdrop function.

In conjunction with each figure illustrate of the present utility model have break alarm and anti-usurp, the operation principle of the telephone set of anti-eavesdrop function is as follows:

When being access on the telephone line when usurping telephone set and off-hook, telephone line voltage drops to 8-10V by 60V (switch that has is 48V).The line voltage distribution testing circuit sends control signal and starts the interference source oscillating circuit and make and occur interference noise continuously on the telephone line, appropriator can't be conversed, and meanwhile the accident alarming circuit sends chimes of doom, tells the victim, telephone line is usurped by the people, so that in time handle.

Under normal circumstances, behind this receiver off-book, the off-hook switching circuit can send an inhibition signal makes the interference source oscillating circuit quit work, and can not take place to disturb and the warning phenomenon in this machine communication process.

When telephone line was cut off by the people, the utility model can make the accident alarming circuit working send whistle cry by the 6-9 volt packed cell power supply of built-in, tells victim's telephone line that very accident generation is arranged, so that in time handle.

Fig. 2 show of the present utility model have break alarm and anti-usurp, the circuit theory diagrams of an embodiment of the telephone set of anti-eavesdrop function, in conjunction with Fig. 1 and Fig. 2, the circuit that further specifies each module among Fig. 1 is formed and operation principle.

The line voltage distribution testing circuit is by transistor T R2, TR3, and TR4 and attached Resistor-Capacitor Unit constitute.Zener diode ZD1 and transistor T R2 constitute family of power and influence's level sensitive circuit, select different Zener diode Vz values for use, can realize different detection level.Select the VZ=20 volt herein for use.TR3 and TR4 constitute the cascaded switch circuit, are used to open and close the interference source oscillating circuit.

The interference source oscillating circuit constitutes the positive feedback oscillator by four NAND gate, and its output signal is sent into telephone line by vdd terminal, is used for disturbing the person that usurps the phone, makes it to be difficult to normal talking.Meanwhile this oscillator is exported one road signal and is delivered to the accident alarming circuit by resistance R 4.

The signal output waveform of interference source oscillating circuit is not strict with, but its oscillating voltage amplitude is advisable with Vp-p 〉=5V, so oscillator can be made of any one circuit of blocking oscillator, resistance-capacitance oscillator, multivibrator and transformer-coupled oscillator.Embodiment adopts resistance-capacitance oscillator in order to reduce cost.

The accident alarming circuit can be selected the alarm of various ways for use, even by relay or photoelectrical coupler control secondary circuit, starts security system or put through alarm call.The utility model is only selected the buzzer B1 of valency health and light-emitting diode D1 formation sound, light alarm mechanism.Alarm signal constitutes common emitter amplifier from the interference source oscillating circuit by R4 and TR1, and is luminous to promote buzzer B1 sounding and diode (LED).

Power backup circuit is made of 9 volts of packed cells of 6F22 type and isolating diode D2.When circuit is cut off by other people, alarm is powered by this back-up source.

The off-hook switching circuit is made of rectifier bridge heap BR2 and photoelectrical coupler O1.The resistance size of its peripheral cell resistance R 10 can be controlled to report to the police and start sensitivity.

General phone phone 6 is a common key-press formula electronic telephone, can select the compatible desk-top phone of P/T for use, also is applicable to hands-free phone or cordless telephone and fax machine.

The utility model telephone set can install another telephone set (secondary machine) additional with the secondary machine transplanting of rice mouth 7 of phone.When outside line was called, no matter main frame or secondary machine, first off-hook person can converse, and conversation sound is not heard tool conversation function of keeping secret by another machine.

Adopt between secondary machine transplanting of rice mouth 7 and the main frame and race to be the first to answer a question the priority circuit, when Zener diode ZD2 in the load circuit of bridge heap BR3 carries machine with main frame and during conducting, controllable silicon S1 conduction, bridge heap BR3 both end voltage is reduced to about 1 volt, this moment, low pressure can not make Zener diode ZD3 conducting, bridge heap BR4 is turned off, and secondary machine loses conversation power, and can't hear the conversation sound of main frame.Otherwise when incoming call was arranged, secondary machine was carried machine earlier, then BR4 conducting, and secondary machine can be conversed, and host bridge heap BR3 is turned off, main frame loses conversation power, also can't hear secondary machine conversation sound simultaneously, plays the effect that conversation is maintained secrecy.

Its circuit working principles illustrated is as follows:

1. be connected to polarity switching BR1 at the telephone line input, insert when the utility model inserts telephone line behind the BR1 not polarity.Voltage after polar switching is delivered to the base stage of TR2 through resistance R 6 and voltage-stabiliser tube ZD1.VCC has the positive voltage of 60V (or 48V) between over the ground approximately under the hook state when circuit is not usurped by other people, and this voltage can make the ZD1 conducting, and the TR2 base stage has enough positive potentials than emitter, thereby TR2 is in conducting state.Its collector potential is level closely.Even also TR3 base earth, thus TR3 is ended, and collector potential rises, and TR4 is ended, V _DDPower supply is cut off, and makes the interference oscillatory circuit lose oscillating condition.In this state, the user carries the machine number dialing telephone call and is not affected, as there not being the interference source oscillating circuit.

2. when telephone line is usurped by the people, incorporate circuit into and make line voltage distribution reduce to 8-10V owing to usurp phone, ZD1 is in off state under this low-voltage.(the voltage stabilizing value of ZD1 is selected 20V), TR2 ends and then makes TR3 and TR4 conducting, and the interference source oscillating circuit is because of feeder ear V _DDEnough voltage is arranged and starting of oscillation, interference signal is sent to outside line by TR4 and polarity switching BR1, usurps telephone set and is interfered and can't uses.

3. the course of work of warning circuit:

Alarm signal is taken from the output of interference source oscillating circuit, and oscillating voltage is delivered to the base stage of TR1 through resistance R 4, amplifies back buzzer B1 through cascode and sends whistle cry and report to the police, and carries out the light warning by LED simultaneously.

4. the cut accident alarming of telephone line

When telephone line was cut off by other people, the polar switching bridge circuit did not have voltage output.Because the existence of built-in back-up source makes the VCC end still have supply power voltage, this voltage is powered to complete machine through isolating diode D2 by built-in back-up source Ei.So the line voltage distribution testing circuit is still in running order.Because polarity switching no-voltage output, so TR2 is in cut-off state, the collector electrode of TR2 is in high potential, causes the TR3 conducting, thereupon TR4 conducting and make interference source signal generator feeder ear V _DDVoltage is arranged, and the work of interference source oscillating circuit is delivered to cascode amplifier tube TR1 through resistance R 4 with oscillator signal and is amplified, and by buzzer D1 sounding alarm, the lumination of light emitting diode of going here and there simultaneously in buzzer circuit is reported to the police

Claims

One kind have break alarm and anti-usurp, the telephone set of anti-eavesdrop function comprises general phone circuit unit 5, the accident alarming unit 4 that the interference source oscillation circuit unit 3, input that its feature also is to comprise the line voltage distribution detecting unit 1 that is connected with the exchange line terminals respectively and off-hook switch element 2, input connection line voltage detection unit 1 output and output all are connected with described interference source oscillation circuit unit 3, described general phone circuit unit 5 also is connected with off-hook switching circuit unit 2 with described interference source oscillation circuit unit 3.
2. according to claim 1 have break alarm and anti-usurp, the telephone set of anti-eavesdrop function, it is characterized in that described off-hook switching circuit unit 2 mainly is made of rectifier bridge heap BR2 and photoelectrical coupler O1.
3. according to claim 1 have break alarm and anti-usurp, the telephone set of anti-eavesdrop function, it is characterized in that, described line voltage distribution detecting unit 1 comprises transistor T R2, TR3, TR4, constitutes the Zener diode ZD1 of family of power and influence's level sensitive circuit, wherein the cascaded switch circuit of transistor T R3 and TR4 formation with transistor T R2.
4. according to claim 1 have break alarm and anti-usurp, the telephone set of anti-eavesdrop function, it is characterized in that, described interference source oscillation circuit unit 3 constitutes the positive feedback oscillator by four NAND gate, one road output signal is sent into telephone line, and another road output signal is delivered to accident alarming circuit unit 4 by resistance R 4.
5. according to claim 1 have break alarm and anti-usurp, the telephone set of anti-eavesdrop function, it is characterized in that, described accident alarming circuit unit 4 can be the alarm of various ways, can be by relay or photoelectrical coupler control secondary circuit, start security system or put through alarm call.
6. according to claim 1 have break alarm and anti-usurp, the telephone set of anti-eavesdrop function, it is characterized in that described accident alarming circuit unit 4 can be to constitute sound, light alarm mechanism by buzzer B1 and light-emitting diode D1.
7. according to claim 1 have break alarm and anti-usurp, the telephone set of anti-eavesdrop function, it is characterized in that also comprise a back-up source unit 6, it comprises battery and isolating diode D2.