CN1365228A - User special wire interface circuit and its operation method - Google Patents
User special wire interface circuit and its operation method Download PDFInfo
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- CN1365228A CN1365228A CN01135940A CN01135940A CN1365228A CN 1365228 A CN1365228 A CN 1365228A CN 01135940 A CN01135940 A CN 01135940A CN 01135940 A CN01135940 A CN 01135940A CN 1365228 A CN1365228 A CN 1365228A
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04M—TELEPHONIC COMMUNICATION
- H04M19/00—Current supply arrangements for telephone systems
- H04M19/02—Current supply arrangements for telephone systems providing ringing current or supervisory tones, e.g. dialling tone or busy tone
- H04M19/026—Arrangements for interrupting the ringing current
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04M—TELEPHONIC COMMUNICATION
- H04M9/00—Arrangements for interconnection not involving centralised switching
- H04M9/08—Two-way loud-speaking telephone systems with means for conditioning the signal, e.g. for suppressing echoes for one or both directions of traffic
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04M—TELEPHONIC COMMUNICATION
- H04M19/00—Current supply arrangements for telephone systems
- H04M19/02—Current supply arrangements for telephone systems providing ringing current or supervisory tones, e.g. dialling tone or busy tone
Abstract
A circuit and method for isolating a subscriber line interface circuit ('SLIC') from the ringer generator in a telephone system. Using a gain blocking device to provide a signal gain when the ringer generator is not being utilized and to provide a high impedance when a ringer signal is present. A current mode subscriber line interface circuit (SLIC) for a telephone system in which AC and DC impedances for tip and ring connections of the SLIC are separately set. A ground key detector for a subscriber line interface circuit (SLIC) uses information from the tip and ring voltage sensing resistor and to determine whether the ring side of the telephone line has been grounded, as when a ground key or fault occurs.
Description
The application is that denomination of invention is " a kind of integrated ringer repeat circuit and a method ", and the applying date is June 28 nineteen ninety-five, and application number is dividing an application of 95107776.7 application.
The present invention relates to a kind of user special wire interface circuit that is used for telephone system, more particularly related is a kind of like this curtage user special wire interface circuit, and the device that it does not need to adopt relay or other may make signal on the telephone wire produce serious distortion can be realized interface circuit and such as the isolation between the ac high voltage that comes the self-vibration flow-generator.
Telephone system users special wire interface circuit (SLIC) with one through the two wires of overbalance transmission channel (promptly lead to and from the path of subsets) with one not counter-balanced four line transmission channels (being the path between the telephone office) be connected.SLIC has multiple function, comprises battery supply feed, overvoltage protection, generation ring, sends signal, mixing, timing etc.
The operation principle of SLIC is known, thereby needn't elaborate, and only 1 does simple exemplary introduction in conjunction with the accompanying drawings below.Current mode SLIC 10 (that is handle current signal in the transmission channel rather than voltage signal) uses the plug tip voltage detecting resistance R 1 of the two wires side that is positioned at SLIC and ringing voltage to detect the current information that resistance R 2 is produced.This information is sent to hybrid circuit 12, the signal of this electric circuit inspection input, and they are delivered to correct direction.Hybrid circuit 12 combines with the external circuit 14 that is connected to the four line sides of SLIC, is used to realize suitable amplification, mixes elimination of conversion echo and impedance matching.
The present invention relates to the application of signal in telephone circuit that ring generator produces.Referring to accompanying drawing 2, SLIC 30 can expression links to each other with a telephone set (by resistance 32) with ring path (T path and R path) by the plug tip path.When plug tip path and ring path carried voice signal, this voltage of signals amplitude was generally the magnitude of 3V, and required current amplitude is generally the magnitude of 4mA, and bandwidth is up to 16KHZ, and precision (distortion in other words) grade is approximately the magnitude of some thousandths of.The voice transfer signal is two-way, sometimes with the battery supply feed superposition on voice signal, thereby make current amplitude reach 30mA.In addition, when the electric current by circuit changes direction, plug tip path and ring path (with and interior all switches that comprised) can not produce any crossover distortion.
In general, when telephone set detects bell signal between a T-wire and the ring leads, will make telephone set send bell ring.This bell signal is delivered to transmission channel selectively, so that the notice telephone set has one call out to arrive, this bell signal will remain in the transmission channel always, until off-hook, till calling reacted.Although plug tip path and ring path all both be used for transmission of speech signals, also be used to transmit bell signal (not necessarily simultaneously), but the characteristics of these two kinds of signals are distinct.For example, the maximum generating positive and negative voltage amplitude of a representative bell signal can reach 150V, and current amplitude reaches 200mA, and bandwidth is 75HZ.In general, the distortion of bell signal and crossover distortion are unimportant for bell signal.
The combination of above-mentioned two types signal (that is voice transfer signal and bell signal) has caused the circuit between following requirement: SLIC and the telephone set must play the effect of binary channels multiplexer (perhaps switch), and one of them switch should allow voice signal by being unlikely to influence its bandwidth and the distortion factor; And the big electric current that another switch should allow ring generator produce passes through, and can bear and block very high ringing signal voltage when switch is cut off.Referring to accompanying drawing 2, master cock SW1 and SW2 selectively are so that the bell signal that ring generator 34 is produced is delivered to transmission channel.When bell signal is delivered to transmission channel or before, make open circuit between ring generator and the SLIC by switch SW 3 and SW4, so that protection SLIC.
Can satisfy above-mentioned requirements by adopting relay in the prior art.As everyone knows, relay forms short circuit when logical, forms open circuit when disconnected.In general, relay has desirable switching characteristic, can satisfy the precision and the bandwidth requirement of voice switch simultaneously, and the electric current and voltage requirement of ring switch.Electromagnetic relay is that the those of ordinary skill in the present technique field is known, but shortcoming is comparatively expensive, and response speed is slower, need occupy bigger very precious circuit area, and energy resource consumption is bigger.Therefore, another kind of known technology adopts solid-state switch and multiplexer, yet these devices far are not desirable devices, can not fully satisfy above-mentioned all requirements simultaneously.In known technology, it is integrated that people attempt required solid-state switch that the hybrid circuit with SLIC is in series, yet its result normally greatly reduces the quality of voice signal.
The objective of the invention is to reduce two wires echo (return) loss of SLIC by impedance matching.The two wires subscriber's line is that typical resistance value is the transmission line of hundreds of Europe (for example 600-9000).The SLIC that is connected with subscriber's line requires to have impedance for matching, so that prevent to produce two wires echo, that is two line return losses.Normally realize impedance matching by a synthetic impedance with the two wires transmission line is big to the two wires impedance Z o that equates in the four line sides of SLIC.This resultant impedance Zo combines with transmission signals electric current I TX, combines with acknowledge(ment) signal electric current I RX then, so that an impedance correction factor is provided, this rectification factor makes the impedance of SLIC and two line impedences be complementary or be complementary basically.Connect transmission channel 18 by one and provide impedance correction factor K1, Z0 with the impedance component 20 of accepting path 16.Before 20 pairs of signals of accepting on the path 16 of the above-mentioned impedance component of employing are proofreaied and correct, regulate the signal gain of accepting in the path 16 by impedance component 22.Gain-adjusted factor K2Z0 and above-mentioned impedance correction factor are relative to each other, and the gain-adjusted factor is the function (K1 〉=K2) generally speaking of impedance correction factor.
On function, the working method of the two wires side of current mode SLIC is shown in accompanying drawing 2A.By plug tip voltage and ringing voltage are applied to respectively on resistance R 1A and the R2A, plug tip on the phone line terminal and ringing voltage are converted into electric current, then electric current is delivered to current mirror CM1A and CM2A.Described current mirror is disclosed for No. 4203012 by United States Patent (USP).Current mirror provides one or more reproducing signals of an input signal, also can be a current amplifier, and the electric current that is reflected is amplified N doubly, and N can be greater than 1, also can be less than 1.When a current mirror provided a plurality of replica current, each replica current can be multiplied by different N.
Voltage on plug tip electric current I 1A and the telephone wire plug tip line is directly proportional, and the voltage on ringing current I2A and the telephone wire ring line is directly proportional.
I1A=(earth potential-Vtip)/R1A (1)
I2A＝(Vring-Vbattery)/R2A (2)
By increasing I1A, the I2A gain in current gain piece G1A and G2A, provide resultant impedance for the two wires side with suitable numerical value.Will be appreciated that above-mentioned resultant impedance is the function of resistance and gain.For example, the impedance at plug tip and ring line place is:
Ztip＝R1A/(1+G1A) (3)
Zring＝R2A/(1+G2A) (4)
Yet resistance R 1A, R2A and gain G 1A, G2A are not independent of each other, when an impedance is regulated, must be changed simultaneously.Therefore because gain may be very complicated, this adjusting is common and be not easy.
Some telephone systems adopt the mode on the ring side joint ground that makes telephone wire to send signal to the operator, and such signal is referred to as earth key.In such system, can provide adjunct circuit to indicate an earth key.Yet such adjunct circuit has increased the complexity of circuit, has increased the possibility that connection error occurs.Therefore, need to reduce to be used to detect the required adjunct circuit of earth key.
SLIC preferably has the self-protection function to fault, for example ground connection that the lineman is caused once in a while, feed line off-line or the like.If SLIC is detection failure not, it will move under short-circuit condition so, and can produce superheating phenomenon.
An object of the present invention is to SLIC provides a kind of new earth key detector and a kind of method that detects earth key, this method can overcome existing problem in the prior art.
Another object of the present invention is for SLIC provides a kind of new earth key detector and a kind of method that detects earth key, wherein indicates described earth key by plug tip electric current and ringing current and a reference current are compared.
Other purposes of the present invention are: a kind of method and apparatus that is used for SLIC and bell signal and telephone set coupling is provided; The method and apparatus that a kind of SLIC of making and bell signal are isolated, can obviously not reduce voice signal simultaneously again is provided; A kind of method and apparatus is provided, the isolated device of other parts in SLIC and the telephone circuit is integrated in the same integrated circuit of SLIC.
The circuit that is used for telephone system of the present invention comprises: a user special wire interface circuit (SLIC) has the plug tip and the ring path that are electrically connected with SLIC and telephone set; A ring generator that is used to produce bell signal; Be used for selectively described bell signal being delivered to the switch of plug tip and ring path; One is used to make the isolated optional gain setting of described SLIC and bell signal to block device.
The present invention also provides a kind of plug tip and the AC impedance of ring line and circuit of dc impedance that is used to set a user special wire interface circuit (SLIC), comprises first device, is used to provide the average current of the DC component of SLIC plug tip and ringing voltage; Second device is used to provide the average current of the alternating current component of SLIC plug tip and ringing voltage; The 3rd device is used for changing the alternating current component average amplitude with respect to described DC component average amplitude, thereby sets the AC and DC impedance respectively.
The present invention further provides a kind of user special wire interface circuit (SLIC), comprised first and second current mirrors, be used for providing independently plug tip electric current and the ringing current that is directly proportional with plug tip and ringing voltage respectively in the two wires of this SLIC side; The DC filter and first averager are used to provide the average current of the DC component of plug tip electric current and ringing current; One second averager is used to provide the average current of plug tip electric current and ringing current; The device of average current that is used for providing the alternating current component of plug tip electric current and ringing current by the DC component mean value of eliminating plug tip electric current and ringing current; A current amplifier is used to amplify the mean value of the alternating current component of plug tip electric current and ringing current, and the replica current of the process amplified current that described current amplifier is produced is delivered to a voltage transmission line of the four line sides that are positioned at SLIC; The received current that provides one to be directly proportional with the reception voltage of the four line sides of SLIC is provided a voltage-current converter; A composite set is used for providing a feedback current by making up to described received current, from the mean value of the alternating current of the amplification of described current amplifier and from the mean value of the direct current of described first averager; And two amplifiers, be used to amplify described feedback current, and will deliver to the two wires side of SLIC through the feedback current that amplifies.
Below in conjunction with accompanying drawing embodiments of the invention are described.
Accompanying drawing 2 is functional-block diagrams of above-mentioned known SLIC, telephone set, switch and ring generator;
Accompanying drawing 2A is the part block diagram of above-mentioned known SLIC, has shown the operation principle of the two wires side of SLIC;
Accompanying drawing 3 is part block diagrams of a kind of circuit of the present invention;
Accompanying drawing 4 is part block diagrams of the another kind of circuit of the present invention;
Accompanying drawing 5 is part block diagrams of another circuit of the present invention, has at length shown a kind of embodiment that can be used for operational amplifier of the present invention;
Accompanying drawing 6 is part block diagrams of another circuit of the present invention, has shown the protection to the testing circuit that is connected with SLIC;
Accompanying drawing 7 is part block diagrams of a kind of embodiment of SLIC of the present invention, has shown the operation principle of the two wires side of SLIC;
Accompanying drawing 8 is part square frame and partial circuit figure of an embodiment of the present invention, wherein AC impedance and dc impedance is set respectively;
Accompanying drawing 9 is block diagrams of a kind of embodiment of earth key testing circuit of the present invention;
Accompanying drawing 10 is block diagrams of a kind of embodiment of failure detector circuit of the present invention, has wherein adopted earth key testing circuit as shown in Figure 9.
Referring to accompanying drawing 3, wherein adopt identical drawing reference numeral with accompanying drawing 2 components identical, shown in telephone circuit can comprise a SLIC 30, it is electrically connected by circuit and the telephone set of representing with resistance 32 represented with resistance R1, R2 on plug tip path and the ring path.By switch SW 1, SW2 in the future the bell signal of Self-sound-produced bell generator 34 be applied to plug tip path and ring path selectively. Current gain piece 36,38 makes plug tip path and ring path and SLIC 30 be connected to each other under the control of current block drive circuit 40.Above-mentioned current gain piece 36,38 comprises an amplifier 42,44 respectively.
When work, the amplifier 42 in the current gain piece 36 is delivered to the drive signal of SLIC at the plug tip end of SLIC.Current gain piece 38 comprises an amplifier 44 similarly, and it is used to drive ring side.Two current gain pieces 36,38 all are designed to enter tri-state mode selectively, and amplifier ends in this state, and its output presents high impedance.Therefore, when needs make telephone set produce bell ring, with switch SW 1, SW2 closure, and the amplifier 42,44 in the current gain piece 36,38 is ended, even also the output of amplifier 42,44 presents high impedance.When ring generator 34 provided bell signal, this signal drove the plug tip path and the ring path of telephone wire, and the output of current gain piece 36,38 has born the voltage of bell signal.The output that note that current gain piece 36,38 was not cut off with being connected of transmission channel, and only was the voltage that makes them enter high impedance status and bear bell signal.
As shown in Figure 3, when ring generator 34 is closed or when cutting off switch SW 1, SW2 and cut off being connected between ring generator 34 and the transmission channel, amplifier 42,44 can conducting and operate as normal, the current signal that amplifier 42,44 directly provides according to current block 40 drives transmission channel, need in path, not be provided with and to cause distorting or the element of limiting bandwidth, for example switch.Although do not have actual switch original paper by SLIC in the transmission channel of telephone set, amplifier 42,44 itself has played protection SLIC, makes it to be unlikely to bear the effect of ringing voltage.When amplifier 42,44 conductings, they still then are in operate as normal three condition, thereby play SLIC and the isolated effect of ringing signal voltage when they turn-off.
Although what circuit shown in the accompanying drawing 3 adopted is current block, the present invention can easily be used in voltage-type SLIC, that is to say that signal that the amplifier in the gain block 36,38 can produce by a voltage block driving element is driven in the mode of voltage.
Accompanying drawing 4 has shown another kind of embodiment of the present invention, and it is more detailed that accompanying drawing 4 makes a farfetched comparison Fig. 3, and one of them SLIC can drive a telephone wire (and telephone set 32).By the action of switch SW 1, SW2, ring generator 34 is connected with telephone wire.SLIC 30 can comprise 36,38 and current block driving elements 40 of current gain piece, and the device of representing with same reference numerals in its function and the accompanying drawing 3 is similar.
Current block driving element 40 can comprise current source 50,52, they each be connected with operational amplifier 42,44 with diode 58,60 by PNP transistor 54,56 respectively.Similarly, current block driving element 40 can comprise the electric current gate of a village (sink) 70,72, they each be connected with operational amplifier 42,44 with diode 78,80 by NPN transistor 74,76 respectively.
Working method below in conjunction with 4 couples of these embodiment of accompanying drawing describes. Current source 50,52 provides electric current by PNP transistor 54,56 for circuit.Similarly, the electric current gate of a village 70,72 is by the electric current of NPN transistor 74,76 receptions from circuit.Each diode the 58,60,78, the 80th, blocking diode, therefore when operational amplifier 42,44 is in three condition (this moment, transmission channel was driven by ring generator 34), the collector-base junction of PNP and NPN transistor 54,56,74,76 is not in reverse-bias state.For example, if operational amplifier 42 by and be in tri-state state, switch SW 1 is closed, the voltage on the plug tip path will between the positive and negative amplitude of bell signal, change (± 150V).When the voltage on the plug tip path be+during 150V, feedback resistance R3 will make the cathode voltage of diode 58 be+150V, thereby make it to be in reverse-bias state.When the voltage on the plug tip path be-during 150V, feedback resistance R3 will make the cathode voltage of diode 58 be-150V, make diode 58 keep the forward bias state, PNP transistor 54 is under the back-biased state in its collector-base junction keeps normal mode of operation.
In a kind of most preferred embodiment, above-mentioned PNP and NPN transistor are bipolar transistor.Diode and transistor should have suitable junction breakdown performance, so that enable to bear the voltage and current of the bell signal that occurs in the course of the work.
Referring to accompanying drawing 5, the operational amplifier of circuit and current block driving element can comprise a current source 100 of electrical connection, input bipolar transistor 102,104, feedback resistance 150,152 as shown in Figure 4, bipolar transistor 106-124, and diode 130-140.Circuit shown in the accompanying drawing 5 comes work in the mode of the two poles of the earth operational amplifier, and all bias currents and bias voltage provide by current source 100.If current source 100 is connected, this amplifier circuit is operate as normal as same operational amplifier just.Resistance 150,152 and operational amplifier have constituted a current gain piece.For example, the electric current that flows into node IN will flow through resistance 152, form the input that is carried on the input bipolar transistor 102,104, cause this amplifier driving resistor 150, till the voltage on the resistance 150,152 equates.At this moment, the electric current on the node OUT will equal the resistance value ratio that electric current on the node IN multiply by resistance 152,150, that is R152/R150.
Referring to accompanying drawing 5, when current source 100 was cut off, this amplifier ended fully, and node OUT enters high impedance status.For example, if described amplifier ends, and the voltage of general+150V (voltage of bell signal) is applied on the node OUT, and transistor 112,114 and 122 is tied at Qi Ji-base and accepted this voltage, and diode 136,138 reverse bias.On the other hand, if the voltage of general-150V is applied on the node OUT, this voltage will be carried in the collection-base of transistor 120,124 and tie, and diode 130,134 and 140 reverse bias.It should be noted: in this embodiment of the invention, even be applied to voltage on the output node of operational amplifier much larger than the normal voltage value, this amplifier is damaged, because adopted the diode with high breakdown performance, they are in the forward bias state when amplifier is worked.
Usually, SLIC not only has the function that drives transmission channel, also has many other functions simultaneously, comprises that eliminating echo, impedance matching, having more representational is the interface that forms between telephone set and the telephone network.In order to realize these functions, often need be the state of SLIC sense transmission line, the particularly state that telephone set produced, for example earth key, hooking etc.In known system, often need prevent from high voltage relevant with bell signal and high electric current are applied on such detecting element.Therefore, on transmission channel, above-mentioned detecting element and circuit thereof are placed the back of switch usually, so that when applying bell signal, make these elements and transmission channel isolated.Because the present invention does not adopt conventional switch with SLIC and bell signal, therefore just need to adopt the mechanism that is different from known technology to protect detecting element.
Referring to accompanying drawing 6, can be used for the detecting element of SLIC by using the resistance protection with big resistance of connecting with detecting element.Present embodiment can comprise current gain piece 30,36, and its work is identical with the embodiment shown in the accompanying drawing 4 with type of drive.Current block driving element 40 is driven by hybrid circuit 90, and this point is also identical with accompanying drawing 4.The state of current mirror 92,94 detected transmission paths, and detected information delivered to (in mode or other modes of current mirror signal) hybrid circuit, so that further process, and under possible situation, produce response.If ringing voltage is applied on the current mirror 92,94, just make current mirror overload and/or impaired danger.Therefore, can be in series by the resistance 96,98 that makes current mirror 92,94 and big resistance and protect the detection path of leading to current mirror 92,94.
Resistance 96,98 shown in the accompanying drawing 6 produces the electric current that is sent to current mirror 92,94 as transducer, and this electric current finally is sent to hybrid circuit, handles there, so that realize various functions.It should be noted: in this embodiment of the invention, when being applied to bell signal on the telephone wire, not that above-mentioned detection resistance is switched on outside the circuit, but the state that keeps they and plug tip path to be connected with the ring path.Because resistance 96,98 has relatively large resistance, so they can bear the voltage of bell signal.In a kind of most preferred embodiment, the resistance of resistance 96,98 can be the order of magnitude of 100K.
Preferably allow the transistor (not shown) and the current mirror 92,94 that are in cut-off state usually be in parallel, although this point is not necessary.If adopt such transistor, when bell signal was sent to plug tip path and ring path, described transistor will be in saturation condition, so just can make it not flow into hybrid circuit 90 with the electric current in the resistance 96,98 from current mirror 92,94 bypasses.
Embodiment shown in the accompanying drawing 7 is suitable for the SLIC of current mode, if for example only need the DC impedance component is fed back to the two wires side of SLIC, and the adjunct circuit that will illustrate below just not needing to adopt.The synthetic dc impedance that offers plug tip path and ring path is:
ZtipDC＝(R1A+R2A)/(2(1+G1A)) (6)
ZringDC＝(R1A+R2A)/(2(1+G2A)) (7)
If R1A equals R2A, above-mentioned resistance value will and the impedance that calculates of formula (3) and (4) equate.
Filter 301 can be traditional, and comprises the conventional device that is used to make up with average electric current I 1DC and I21DC.
In addition, can provide an I5 who combines by I3 and I4 that an alternating current component is provided, thereby eliminate DC component by in second averager 32, electric current I 1 and I2 being averaged.
I4＝(I11+I21)/2＝(I11DC+I21DC+I11AC+I21AC)/2
(8)
I5＝I4+(-I3)＝(I11AC+I21AC)/2 (9)
As implied above, if the constituted mode of current mirror CM11 and CM22 makes that reflected current is half of incident current, then need in averager 32, not remove the mean value that promptly can obtain electric current I 11 and I21.
Accompanying drawing 8 has shown a kind of improvement embodiment of circuit of SLIC in the mode of block diagram.These square frames comprise conventional device, therefore do not need to be further described the those of ordinary skill in the present technique field.Two wires side by SLIC begins, and plug tip electric current I 1B and ringing current I2B deliver to filter 30B and averager 32B by current mirror CM1B and CM2B.In current duplicator 36B,, the replica current of electric current I 3B is delivered to node 38B and 40B, formed I5B mutually with I4B at this node 38B electric current I 3B of place to duplicating from the DC component of filter 30B.In current duplicator 42B, I5B is duplicated, and it is amplified KB doubly in current amplifier 34B, thereby I6B is delivered to node 40B.I5B also is replicated and is added on the resistance 44B, to form transmission signals voltage Vtx.Acknowledge(ment) signal voltage Vrx is converted device 46B and is converted into and accepts electric current I rx, and is sent to node 40B.At node 40B, electric current I 3B and I6B and Irx addition are to form I9B.I9B is a superposition of accepting electric current, plug tip electric current and ringing current, is used to carry out impedance matching.
I9B＝I3B+I6B+Irx
In current duplicator 48B, duplicate I9B, and the latter is sent to current gain piece 50B and 52B, multiply by factor G therein, deliver to plug tip path and ring path then.
I10＝I9×G
As above-mentioned formula (A) with (B), the embodiment of accompanying drawing 8 provides AC impedance and the dc impedance that can control respectively.It adopts conventional device, and these devices can be included in the integrated circuit, to be provided at the advantage that can obtain matching element among the integrated circuit SLICE.
In the SLIC of a current mode, the information that detects resistance R S1 and RS2 from plug tip and ringing voltage can be used to determine when earth key or fault occurring, whether the ring side of telephone wire is grounded.What realize that the additional device of this function uses is the current information that has existed among the SLIC, and can form an integral body with SLIC.
Plug tip electric current I tip is directly proportional with the voltage of telephone wire plug tip side, and ringing current Iring is directly proportional with the voltage of telephone wire ring side:
Itip＝(GROUN-Vtip)/RS1 (1)
Iring＝(Vring-Vbattery)/RS2 (2)
When press on the telephone set and mobile phone button or because certain is accidental, when making the ring side joint ground of telephone wire, a big longitudinal signal will appear on telephone wire, it is regarded as the DC component of electric current Iring on the telephone wire.Need to come with so vertical direct current signal with as the longitudinal signal difference of the alternating current component that may be introduced in the signal on the telephone wire.Comprise the plug tip side of phone or the situation that the ring side is grounded in this used what is called " fault ".In fact, an earth key only is " fault " with finite time length.
Referring to accompanying drawing 9, wherein hybrid circuit 12C represents with a square frame, has for the sake of clarity omitted external circuit 14C simultaneously in the accompanying drawings.Current mirror 20C, the 22C of SLIC provides the replica current of plug tip electric current and ringing current for hybrid circuit 12C, simultaneously for comparator 24C provides other replica current, so that determine whether ground connection of ring side.Can adopt mode described below to handle to the replica current that offers comparator.
Can be sent to filter 26C, 28C from the electric current I tip of current mirror 20C, 22C and the other replica current of Iring, these two filters are removed AC signal (comprise and exchange longitudinal signal) wherein, and keep direct current plug tip electric current I tdc and ringing current Irdc.Above-mentioned direct current plug tip electric current and ringing current can combine with the reference current from a current source 30C, and are sent to comparator 24C.The electric current I gk at node 32C place is used for determining whether to exist ground connection at comparator 24C, its numerical value equal DC signalling electric current I rdc deduct direct current plug tip electric current I tdc and reference current Iref and:
Igk＝Irdc-(Itdc+Iref) (3)
If Irdc is greater than (Itdc+Iref), that is Igk be on the occasion of, comparator 24C will produce first output; If Irdc is less than (Itdc+Iref), that is Igk is negative value, and comparator 24C will produce second output (perhaps no-output).If want comparator 24C to produce first output, the difference of DC signalling electric current I rdc and direct current plug tip electric current I tdc just must be at least greater than reference current Iref.So that during expection direct current longitudinal signal that representative is produced by the detected ground connection of this comparator, positive Igk just indicates and the direct current longitudinal signal that caused by ground connection occurred on telephone wire when as required reference current being set.In normal operation, can be used to this signal in the mode of routine, so that an earth key indication is provided from comparator 24C.Although a ground connection indication of ring side also can be indicated a fault, the response of SLIC can be identical.In other words, it can come the electric current of self-feedback amplifier to protect himself by restriction in the time durations of this indication occurring, and it is overheated to prevent to produce.
Plug tip side at telephone wire also may break down, yet it is not considered as an earth key (that is it is not a signal that sends to the operator).Referring to accompanying drawing 10, can improve the circuit shown in the accompanying drawing 9, detect the fault that the plug tip side occurs by adding another comparator 40C.Can will deliver to filter 42C, 44C from the Itip of current mirror 20C and 22C and the other replica current of Iring, this filter is removed AC signal (comprise and exchange longitudinal signal), keeps direct current plug tip electric current I tdc and ringing current Irdc.Above-mentioned direct current plug tip electric current and DC signalling electric current can be combined with a reference current from current source 46C, deliver to above-mentioned comparator 40C then.The electric current I pf at node 48C place is used for determining whether there is fault in the plug tip side at comparator 40C, its numerical value equal direct current plug tip electric current I tdc deduct DC signalling electric current I rdc and reference current Iref and:
Ipf＝Itdc-(Irdc+Iref) (4)
If Itdc is greater than (Irdc+Iref), that is Ipf be on the occasion of, comparator 40C will produce first output; If Itdc is less than (Irdc+Iref), that is Ipf is negative value, and comparator 40C will produce second output (perhaps no-output).If want comparator 40C to produce first output, the difference of direct current plug tip electric current I tdc and DC signalling electric current I rdc just must be at least greater than reference current Iref.So that expression is when detecting fault caused expection direct current longitudinal signal of plug tip side by comparator 40C, positive Igk just indicates on telephone wire plug tip side and the direct current longitudinal signal that caused by fault occurred when as required reference current being set.In normal operation; can be used to this signal in the mode of routine from comparator 40C; so that a faulty indication is provided, so as in the time durations of this indication to occur by restriction come the electric current of self-feedback amplifier protect SLIC himself, it is overheated to prevent to produce.
In a word, the invention provides a kind of isolated circuit and method of ring generator that makes in user special wire interface circuit (SLIC) and the telephone system.Adopt a gain to block device, a kind of signal gain is provided when not using ring generator, high impedance is provided when the bell signal signal occurs.The present invention also provides a kind of current mode user special wire interface circuit that is used for telephone system, and wherein the AC and DC impedance of plug tip path among the SLIC and ring path is set respectively.The present invention also provides a kind of earth key detector that is used for user special wire interface circuit, and it is used to the information from plug tip voltage and ringing voltage detection resistance R S1 and RS2, determines when earth key or fault occurring whether the ring side of telephone wire is grounded.
Claims (20)
1. the AC impedance of a TR tip and ring line that is used to set a user special wire interface circuit (SLIC) and the circuit of dc impedance comprise: first device is used to provide the average current of the DC component of SLIC TR tip and ring voltage; Second device is used to provide the average current of the alternating current component of SLIC TR tip and ring voltage; And the 3rd device, be used for changing the alternating current component average current value, thereby set the AC and DC impedance respectively with respect to described DC component average current value.
2. circuit as claimed in claim 1, wherein said first device comprises a DC filter, is used for eliminating the plug tip electric current that is directly proportional with TR tip and ring voltage and the alternating current component of plug ring electric current; And first averager that is used for the average DC component that is kept.
3. circuit as claimed in claim 1, wherein said second device comprise second averager that is used for average plug tip electric current and plug ring shunting; And the combiner of the mean value of plug tip electric current that is used to make up the DC component mean value that produced by described first device and is produced by described second averager and plug ring electric current is so that provide the mean value of alternating current component.
4. circuit as claimed in claim 1, wherein said the 3rd device comprise the device of the gain that is used to increase the alternating current component mean value that is produced by described combiner.
5. circuit as claimed in claim 1 comprises the device of the combination that is used to amplify following three amounts:
(A) the DC component mean value that produces by described first device;
(B) the alternating current component mean value that produces by described the 3rd device through amplifying;
(C) one is proportional to the current value of accepting voltage;
And will through the TR tip and ring line that the combined value that amplification is delivered to SLIC.
6. circuit as claimed in claim 1, wherein said the 3rd device comprises a voltage amplifier between two resistance, is used to amplify the mean value of alternating current component; The resistance ratio of described two resistance has been set SLIC four lines to the gain of two wires and to the AC impedance of TR tip and ring line.
7. current mode user special wire interface circuit (SLIC) that is used for telephone system, this SLIC comprises the current device of the AC impedance of the TR tip and ring line that is used for setting respectively this SLIC and dc impedance and is used for setting the resistive device of four lines of SLIC to the two wires gain dividually with the gain of SLIC two wires to four line.
8. two wires to four line that is used to set a user special wire interface circuit (SLIC) and four lines comprise to the circuit of two wires gain: first device is used to provide the average current of the DC component of SLIC TR tip and ring voltage; Second device is used to provide the average current of the alternating current component of SLIC TR tip and ring voltage; And the 3rd device, the variation that is used to be independent of described DC component average current amplitude changes alternating current component average current amplitude, thereby sets the line gain of SLIC two wires to four respectively and SLIC four lines gain to the two wires.
9. circuit as claimed in claim 8, wherein said the 3rd device comprises that two voltage amplifiers between the resistance are used for amplifying the average current value of alternating current component, and the impedance ratio of wherein said two resistance is set SLIC four lines and is gained to the two wires, and impedance setting SLIC two wires to four line of a resistance gains in the described resistance.
10. user special wire interface circuit (SLIC) that is used for telephone system, this SLIC comprise the current-mode device that SLIC four lines to two wires gain and SLIC two wires to four line gains are set independently.
11. SLIC according to claim 10, wherein said current-mode device also comprise the device of the AC and DC impedance of the TR tip and ring connection that independently is provided for SLIC.
12. a user special wire interface circuit (SLIC) comprises first and second current mirrors, is used for providing respectively with TR tip and ring voltage is directly proportional in the two wires of this SLIC side separating plug tip electric current and plug ring electric current; A DC filter and one first averager are used to provide the average current of the DC component of plug tip electric current and plug ring electric current; One second averager is used to provide the average current of plug tip electric current and plug ring electric current; Be used for providing the device of the average current of plug tip electric current and plug ring electric current alternating current component by the DC component mean value of eliminating plug tip electric current and plug ring electric current; A current amplifier is used to amplify the mean value of the alternating current component of plug tip electric current and plug ring electric current, and the replica current of the process amplified current that described current amplifier is produced is delivered to a voltage transmission line of the four line sides that are positioned at SLIC; The received current that provides one to be directly proportional with the reception voltage of the four line sides of SLIC is provided a voltage-current converter; Combiner apparatus is used for the mean value by the alternating current that amplifies to described received current, by described current amplifier and the mean value of the direct current that produced by described first averager makes up a feedback current is provided; And two amplifiers, be used to amplify described feedback current, and will deliver to the two wires side of SLIC through the feedback current that amplifies.
13. SLIC according to claim 12, wherein said current amplifier also comprises two voltage amplifiers between the resistance, be used to amplify the average current of alternating current component, and the resistance value ratio of wherein said two resistance is provided with the AC impedance that SLIC four lines gain to the two wires and are used for the TR tip and ring line.
14. the AC impedance of a TR tip and ring line that is used to set a user special wire interface circuit (SLIC) and the method for dc impedance may further comprise the steps: the average current that the DC component of SLIC TR tip and ring voltage (a) is provided; (b) provide the average current of the alternating current component of SLIC TR tip and ring voltage; (c) change the alternating current component average amplitude with respect to described DC component average amplitude, thereby set the AC and DC impedance respectively.
15. method as claimed in claim 14, wherein said first device comprises a DC filter, the average current that plug tip electric current that is directly proportional with TR tip and ring voltage by filtering and the alternating current component in the plug ring electric current provide DC component; And the electric current of the average DC component that keeps.
16. method as claimed in claim 14, wherein by average TR tip and ring electric current, the average current of the DC component from average TR tip and ring electric current in the removal process (a) provides the average current of alternating current component.
17. method as claimed in claim 14, also be included in the step that voltage amplifier is provided between two resistance on the transmission voltage line, being used to set SLIC four lines gains to the two wires, with the AC impedance that is used for the TR tip and ring line, the resistance value ratio of wherein said two resistance is set this gain and AC impedance.
18. the method for a current mode user special wire interface circuit that is used to operate be used for telephone system, comprise the TR tip and ring line that is provided for SLIC independently the AC and DC impedance step and SLIC four lines are set independently to two wires gain and the gain of two wires to four line.
19. two wires to four line gain that is used to set a user special wire interface circuit (SLIC) and four lines to the method for two wires gain, comprise the steps: to provide the average current of the DC component of SLIC TR tip and ring voltage; The average current of the alternating current component of SLIC TR tip and ring voltage is provided; The variation that is independent of described DC component average amplitude changes the alternating current component average amplitude, and SLIC two wires to four line gains and SLIC four lines gain to the two wires thereby set respectively.
20. an operation is used for the method for the user special wire interface circuit (SLIC) of telephone system, comprises setting the step of SLIC four lines to two wires gain and the gain of SLIC two wires to four line independently.
Applications Claiming Priority (6)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US08/267,434 | 1994-06-29 | ||
| US08/267,436 US5515417A (en) | 1994-06-29 | 1994-06-29 | Ground key detector for a SLIC |
| US08/269,133 | 1994-06-29 | ||
| US08/267,436 | 1994-06-29 | ||
| US08/267,434 US5515434A (en) | 1994-06-29 | 1994-06-29 | Impedance setting circuit for a SLIC |
| US08/269,133 US5517565A (en) | 1994-06-30 | 1994-06-30 | Integrated ringer relay circuit and method |
Related Parent Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN 95107776 Division CN1136743A (en) | 1994-06-29 | 1995-06-28 | Relay circuit and method of integrated signalling set |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN1365228A true CN1365228A (en) | 2002-08-21 |
Family
ID=27401968
Family Applications (2)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN01135941A Pending CN1367603A (en) | 1994-06-29 | 2001-10-29 | Grounding key and fault detector and its detection method |
| CN01135940A Pending CN1365228A (en) | 1994-06-29 | 2001-10-29 | User special wire interface circuit and its operation method |
Family Applications Before (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN01135941A Pending CN1367603A (en) | 1994-06-29 | 2001-10-29 | Grounding key and fault detector and its detection method |
Country Status (4)
| Country | Link |
|---|---|
| JP (1) | JPH0851652A (en) |
| KR (1) | KR960003260A (en) |
| CN (2) | CN1367603A (en) |
| GB (1) | GB2290921A (en) |
Families Citing this family (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US6567521B1 (en) * | 1999-08-17 | 2003-05-20 | Silicon Laboratories, Inc. | Subscriber loop interface circuitry having bifurcated common mode control |
| SE0002350L (en) | 2000-06-21 | 2001-12-22 | Ericsson Telefon Ab L M | A method of generating a ring signal in a subscriber line circuit |
Family Cites Families (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4652701A (en) * | 1985-11-06 | 1987-03-24 | At&T Information Systems, Inc. | Ringing application circuit |
| AU593951B2 (en) * | 1986-10-20 | 1990-02-22 | Fujitsu Limited | An integrated ringing circuit and a ring trip circuit for the same |
| SE459138B (en) * | 1987-10-08 | 1989-06-05 | Ericsson Telefon Ab L M | DEVICE IN A TELECOMMUNICATION SYSTEM FOR CONNECTING AND DISCONNECTING A RING SIGNAL |
-
1995
- 1995-06-26 JP JP7159495A patent/JPH0851652A/en not_active Withdrawn
- 1995-06-27 GB GB9513091A patent/GB2290921A/en not_active Withdrawn
- 1995-06-29 KR KR1019950018286A patent/KR960003260A/en active IP Right Grant
-
2001
- 2001-10-29 CN CN01135941A patent/CN1367603A/en active Pending
- 2001-10-29 CN CN01135940A patent/CN1365228A/en active Pending
Also Published As
| Publication number | Publication date |
|---|---|
| GB2290921A (en) | 1996-01-10 |
| CN1367603A (en) | 2002-09-04 |
| JPH0851652A (en) | 1996-02-20 |
| GB9513091D0 (en) | 1995-08-30 |
| KR960003260A (en) | 1996-01-26 |
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| SE01 | Entry into force of request for substantive examination | ||
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| PB01 | Publication | ||
| C02 | Deemed withdrawal of patent application after publication (patent law 2001) | ||
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