CN1094281C

CN1094281C - Telephone signal testing circuit

Info

Publication number: CN1094281C
Application number: CN 98102612
Authority: CN
Inventors: 黄拔忠
Original assignee: Winbond Electronics Corp
Current assignee: Winbond Electronics Corp
Priority date: 1998-06-18
Filing date: 1998-06-18
Publication date: 2002-11-13
Anticipated expiration: 2018-06-18
Also published as: CN1240320A

Abstract

The present invention relates to a telephone signal testing circuit capable of discriminating subscriber's spectral line conversion or ringing, which is in circuit architecture. The telephone signal testing circuit is added to a ringing testing circuit of a general telephone IC so that the telephone signal testing circuit can judge an input signal is a subscriber's spectral line conversion signal or a ringing signal. Capacitance charging and discharging which occurs when telephone ringing or subscriber's spectral line conversion is carried out is used, Schmidt triggers of two different classes are utilized to test voltage change when the capacitance discharges for the first time and ripples of capacitance charging and discharging generated from ringing, that a signal is a subscriber's spectral line conversion signal or a ringing signal can be judged by a simple trigger, and certain rejection can be carried out on bouncing phenomenon generated when subscriber's spectral line conversion or ringing is started as well.

Description

Telephone signal testing circuit

Technical field

The present invention relates to a kind of telephone signal testing circuit, particularly relate to a kind of telephone signal testing circuit that can distinguish user's line reversal signal (line reversal) or ring signal (ring).

Background technology

Signal application mode when the regular phone machine is in on-hook (on-hook) state, be to interrupt this state by user's line reversal signal or ring signal, and give different definition to different signals, show the sequential of caller's identification code as Fig. 1, the standard of (a) expression BT (British Telecom) among the figure, before ring, promptly there is the signal of caller's identification code to send in the phone, and general phone when hook state be in very-low power consumption or or even the holding state of not power consumption, so before caller's identification code is sent to, user's line reversal signal can appear earlier, receive caller's identification code to wake microprocessor up, later ring signal does not then have caller's identification code.(b) standard of expression Bellcore, caller's identification code is to send to after the ring first time, and when user's line reversal signal occurs, can't send caller's identification code.For the phone that can discern the caller, generally be after the telephone set microprocessor is interrupted, judge it is user's line reversal signal or ring signal according to the length of break period, determine that more whether starting the caller discerns IC.Another kind of easier method is exactly no matter the telephone set microprocessor interrupts by user's line reversal signal or by the ring signal, all the deactivation caller discerns IC, after after a while,, again the caller is discerned IC and close if do not receive the message of caller's identification code.But, no matter be to adopt any method, all can the electricity wasting source power.And, aforementioned first method more can the electricity wasting phone in time of microprocessor.

User's line reversal signal or the testing circuit of ring signal is as shown in Figure 2 in the regular phone machine, because Fig. 2 is in order to the detection action of explanation to the telephone set input signal, so voltage rectifying circuit 10 and ring detecting circuit 20 in the regular phone machine only are shown.In the voltage rectifying circuit 10, capacitor C ₁, C ₂Can stop the direct voltage on end line (tip) and the loop wire (ring).Utilize resistance R ₁, capacitor C ₁Or resistance R ₂, capacitor C ₂Take out and exchange (AC) signal, through D ₁, D ₂, D ₃, D ₄Rectification is to obtain unipolar signal.Enter into ring detecting circuit 20 then, through resistance R ₃, R ₄Take out dividing potential drop, and send into the input RNGDI (ring detectorinput) of Schmidt trigger (Schmitt trigger) 201.Therefore, as long as the signal of end line and loop wire changes enough greatly Q ₁Be about to capacitor C ₃Charge discharge, ring this moment detects output RNGON and becomes electronegative potential immediately.When between the signal of end line and loop wire, no longer include big variation, Q ₁Also just no longer make capacitor C ₃Discharge, power supply V at this moment _CcCan be via resistance R ₅To capacitor C ₃Charging, after a period of time, ring detection output RNGON can reply and be high potential, and the action of detection of end.See also Fig. 3, it shows respectively when the input of user's line reversal signal or ring signal, in the RNGRC position and ring detect the graphic of the locational waveform of output RNGON.By finding out among the figure that when the locational voltage VRNGRC of RNGRC descended, ring detects output RNGON can export electronegative potential.Under normal circumstances, detect the current potential height of output RNGON, can learn that just user's line reversal signal and ring signal come in according to ring.

But when switch starts user's line reversal signal or ring signal, some phenomenons of beating (bounce) occur, make Q through regular meeting ₁Make capacitor C ₃There is the phenomenon of open and close, open and close at the starting point place of discharge, as shown in Figure 4, and at the locational voltage V of RNGRC _RNGRCCan when descending, the fluctuating of similar ripple be arranged, and the mistake that can cause signal to detect.Because capacitor C ₃The speed of discharge is very fast, and the speed of charging is comparatively slow, so in the testing process of RNGRC, for once beating at most can be reflected on the RNGON signal, yet it still may cause the erroneous judgement of signal.

Summary of the invention

Purpose of the present invention promptly is to provide a telephone signal testing circuit, and it is before user's line reversal signal or the detection of ring signal end, and the signal that can distinguish input is user's line reversal signal or ring signal.

Be on telephone signal testing circuit of the present invention is used when the detection of user's line reversal signal or ring signal finishes, to distinguish that signal latchs (latch), send simultaneously and interrupt signal to microprocessor, after microprocessor is interrupted, immediately can be according to distinguishing that signal learns that input signal is user's line reversal signal or ring signal, remove then and interrupt signal, and carry out suitable processing, use the load that reduces microprocessor significantly.

In addition, the present invention is in the design of circuit, then utilize the Schmidt trigger of different filp-flop stages, the Schmidt trigger of high potential filp-flop stage is come in order to detect user's line reversal signal and ring signal, discharge and recharge ripple than what the Schmidt trigger of electronegative potential filp-flop stage occurred on the electric capacity when detecting ring, and be judged as the ring signal according to this.The signal that the jumping phenomena that the ripple decision circuitry is produced in the time of can overcoming switch startup user's line reversal signal and ring signal causes detects goes up contingent mistake.

The present invention's telephone signal testing circuit mainly is the Schmidt trigger that comprises two different filp-flop stages, its filp-flop stage is respectively first voltage and second voltage, with discharging and recharging of the aforementioned electric capacity of work, when voltage is lower than first voltage, filp-flop stage is that the trigger of first voltage can be exported ring detection output signal, when voltage was lower than second voltage, filp-flop stage was that the trigger of second voltage can be corresponding to the ripple output pulse signal that aforementioned capacitor charge and discharge produced.Include the ripple decision circuitry in addition, being subjected to aforementioned filp-flop stage is that the driving and the aforementioned filp-flop stage of the trigger of first voltage is the control of the trigger of second voltage, can be in order to filter the noise that produces because of beating, and after receiving the pulse signal of trigger output that aforementioned filp-flop stage is second voltage, export a ring signal, be electronegative potential and when not having the ring ripple and exporting so when ring detects output signal, can differentiate input signal is user's line reversal signal, but if ring detects output signal is electronegative potential the and when output of ring ripple was arranged, then can differentiate input signal was the ring signal.

For circuit architecture, detection method and the characteristics that more clearly disclose the present invention, existing conjunction with figs. explanation preferred embodiment is as follows, wherein:

Description of drawings

Fig. 1 shows in the communication standard sequential chart for caller's identification code signal;

Fig. 2 shows the circuit that is used to detect user's line reversal signal and ring signal in the known telephone set;

Fig. 3 shows the sequential chart of the testing circuit of Fig. 2;

Fig. 4 shows the schematic diagram that occurs jumping phenomena when switch starts user's line reversal signal or ring signal;

Fig. 5 shows an embodiment graphic of the present invention's telephone signal testing circuit; And

Fig. 6 shows the sequential chart of the testing circuit of Fig. 5.

Embodiment

As shown in Figure 5 be the present invention's telephone signal testing circuit figure, simpler clear in order to make explanation, the circuit part before the RNGDI signal input is omitted.In the drawings, trigger A, B, C form a ripple decision circuitry 40, can absorb effectively to start the pulse of beating that user's line reversal signal or ring signal are produced, and the ripple that electric capacity occurs can judge ring the time.The present invention has used two to have different filp-flop stage V ₁And V ₂Schmidt trigger 31 and 32, wherein, filp-flop stage V ₁＜V ₂, and filp-flop stage is V ₂Schmidt trigger be in order to detecting the envelope (envelope) of ring signal, and filp-flop stage is V ₁Schmidt trigger then be the ripple that capacitor charge and discharge is produced when detecting jingle bell, after trigger triggers, can obtain the signal of identification line reversal signal or ring signal.See also Fig. 6, it shows the waveform sequential chart of foregoing circuit, and wherein, RNGDI represents input signal, Q ₁Represent transistorized switch, V ₂SCHMITT O/P represents that filp-flop stage is V ₂The output of Schmidt trigger, V ₁SCHMITT O/P represents that filp-flop stage is V ₁The output of Schmidt trigger, RING represents the ring signal.For more clearly identification, so will strengthen by the scale of represented period of X among the figure.In Fig. 6, beating of some I place absorbed by trigger A, causes electric capacity that faint discharging and recharging arranged because of beating.If this change in voltage that discharges and recharges drops on V ₁On the level, and cause the triggering of trigger at a J place, then absorb beating of its voltage by trigger B again.By the ripple that the ring signal causes capacitor charge and discharge to produce, the device C that then is triggered at a K place receives, and is reflected on the ring output signal, makes ring signal RING become high potential.Input voltage RNGDI is behind Schmidt trigger 30, with the variation of work input voltage RNGDI, transistor Q ₁Can open and make capacitor C ₃Discharge, or close and make power supply V _CcVia resistance R ₅, to capacitor C ₃Charging.Filp-flop stage is V ₂Schmidt trigger 32 be in order to detecting the envelope of ring signal, that is to say when input voltage less than V ₂The time, the output of Schmidt trigger 32 can become high potential.And filp-flop stage is V ₁31 of Schmidt triggers be the ripple that capacitor charge and discharge is produced when detecting jingle bell.

Aforementioned circuit of the present invention shown in Figure 5, wherein trigger A, the B of ripple decision circuitry 40, C also can be the trigger of negative edge, and it can obtain identical result, and just can to become be to be detected in the process of electric capacity charging to the ring signal.And this ripple decision circuitry 40 also can be to have to enable (Enable) and the counter of removing (Clear) function, discharges and recharges ripple to be reflected at filp-flop stage be V as long as can calculate the ring signal ₁The pulse of Schmidt trigger 31 output, can judge it is the ring signal.

Claims

1. telephone signal testing circuit comprises:

One voltage rectifying circuit in order to receiving the signal from subscribers feeder, and obtains unipolar signal through rectification; And

One testing circuit, in order to detect input signal is user side line reversal signal or ring signal, when the detection of subscribers feeder line reversal signal or ring signal finishes, to distinguish that signal fastenes, send one simultaneously and interrupt signal to a microprocessor, this processor judges that according to recognition signal input signal is subscribers feeder line reversal signal or ring signal immediately after being interrupted.

2, telephone signal testing circuit as claimed in claim 1, wherein, above-mentioned voltage rectifying circuit is made of an electric capacity, a schmitt trigger and a transistor, above-mentioned schmitt trigger receives above-mentioned signal from user's spectral line to control above-mentioned transistor, when above-mentioned transistor ends, above-mentioned capacitor discharge, and during above-mentioned transistor turns, make above-mentioned electric capacity via a power source charges.

3, telephone signal testing circuit as claimed in claim 2, wherein, above-mentioned testing circuit comprises first and second schmitt trigger, its triggering level is respectively first voltage and second voltage, along with discharging and recharging of above-mentioned electric capacity, when voltage was lower than above-mentioned first voltage, above-mentioned first schmitt trigger can be exported a ring and detect output signal, when voltage was lower than second voltage, above-mentioned second schmitt trigger can be exported a pulse signal corresponding to the ripple that aforementioned capacitor charge and discharge produced.

4, telephone signal testing circuit as claimed in claim 3, wherein, above-mentioned first and second schmitt trigger in order to detect the envelope of ring signal, reaches the ripple that capacitor charge and discharge is produced when detecting jingle bell respectively.

5, telephone signal testing circuit as claimed in claim 3, wherein, above-mentioned testing circuit also comprises a ripple decision circuitry, constitute by three triggers, with in order to the output of the schmitt trigger of the envelope that detects the ring signal as its activation with remove input, the output of the schmitt trigger of the ripple that capacitor charge and discharge is produced when detecting jingle bell is as its clock input simultaneously.

6, telephone signal testing circuit as claimed in claim 5, wherein, above-mentioned three triggers, when being used to import high potential, and clock is when being input as rising edge, and the output of trigger equals its input.

7, telephone signal testing circuit as claimed in claim 6, wherein, above-mentioned three triggers, when above-mentioned ring detects output signal is electronegative potential, and when not having the output of ring ripple, can discern input signal is subscribers feeder spectral transformation signal, is electronegative potential if above-mentioned ring detects output signal, and when the output of ring ripple was arranged, can discern input signal was the ring signal.

8, telephone signal testing circuit as claimed in claim 1, wherein, above-mentioned first voltage is greater than above-mentioned second voltage.