JPS58501529A - electronic termination circuit - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed description of the invention] electronic termination circuit Background of the invention field of invention The present invention provides signal conversion between a two-way two-wire signal path and a pair of one-way two-wire signal paths. It relates to a termination circuit that performs conversion.

More specifically, the present invention provides an electronic termination circuit that verifies earth signals. Typically used in traditional telecommunications systems such as telephone systems to perform signal conversion. Concerning the replacement of large (bslhw) hybrid transformers.

Description of prior art Most, but not all, modern telecommunications systems use central office switches. At most i, a pair of unidirectional signals from a balanced two-way subscriber end loop signal path. A hybrid transformer is used to convert the signal into the path. these transformers ensures excellent AC beam/beadance matching between the terminating signal path and the bidirectional transmission path. Reduce and/or reduce signal reverberation (make data delay) must be well matched to the transformer located in the central office equipment in order to eliminate do not have. These transformers are generally very bulky, expensive and bulky. Furthermore, follow When conventional transformers are used, impedance matching adjustment is not a problem. Therefore , the performance of nine communication systems used on such transformers used in modem applications is It may fall.

Therefore, as mentioned above, it can be used instead of the bulky transformers currently in use. An electronic matching device at the end of the subscriber loop line that can be used in typical modems. A termination circuit is required.

Summary of the invention Therefore, it is an object of the present invention to connect a two-way transmission signal path and a pair of one-way transmission signal paths. Modified equipment circuit Wtt used in modem application to perform signal conversion It is possible to serve.

Another object of the present invention is to be geo-compatible and compatible with typical telephone communication systems. We will continue to provide complete electronic termination equipment circuits.

In accordance with the above and its purpose, Nishi II! The echo return at N and its In the two-wire input, the knee difference is transformed and suppressed into a four-way terminal signal of the vertical signal. Electronic termination equipment that connects the subscriber liI terminal layer loosely and interrogates the ground to perform signal separation. An installation circuit is provided. This electronic termination circuit is configured to Two-wire input and subscriber loose interface times to separate tsLIG) and 5LICf combined with nine related circuits.

Brief description of the drawing Figure 1 shows a subscriber line loop interface circuit (5LIc) well known to those skilled in the art. t″ is shown.

FIG. 2 shows an electronic termination circuit of the present invention including the 5LIC of FIG.

Detailed description of the invention Figure 1 shows a two-wire differential signal and a pair of two-wire single-ended (si%gLa - m5d ad) subscriber line loops well known to those skilled in the art for performing signal conversion to and from the signal path. Interface circuit (5LIC) 10 is shown. Generally, 5LIC10 is a telephone office PAEX hybrid transformer circuit and subscriber carrier with two-way telecommunications ill'f: designed to replace φ. 5LIC10 operation and functions is well known in the art, US Pat. No. 4,004,109 and US Pat. No. 25,9 and the teachings of those patents are incorporated herein by reference.

5LIC10 is available for fabrication in monolithic integrated form, e.g. part no. Manufactured by Motorola as MC3419.

5 LIC 10 is typically placed at the central office 1 and connects the telephone Im to the subscriber line loop. Connected at the tip (Tip) k/g (R4ng) terminal via adapted to be used.

Typically, a subscriber network includes a telephone set for two-way signal transmission. Therefore % Incoming signals appearing on the FRX (e.g. transmitted from the calling party via the central office exchange) signal) is received by 5LIC10 and outputs a proportional differential signal at terminals 12 and 14. converted into a signal. Therefore, AC coupling through capacitor 16t and resistor 18 The received signal is connected to PNP and NPN with a balanced AC current proportional to the received input voltage. Terminal 12 via Darlington transistor 20.22 and resistor 24.26 and a friend 5LIC1 that drives (Tsumago) the two-wire output line connected at 14. By converting the current into a current that is processed through the transfer (1 deasah shrid de...ptias) is realized. Similarly, the called Appears on terminals 12 and 14 supplied via a telephone coupled to the The balanced AC voltage signal is converted to a single-ended output signal (by 5LIC10). appears at its output Tx. This conversion is performed by resistor 28. Capacitor 30 and operational amplifier The output V? Output signal ACt coupled to the caller at X - generated let Additionally, resistors 28 and 54 are understood to be together with resistors 66 and 3B. Then, determine the AC termination impedance of 5LIC1o. Furthermore % i’BX By taking advantage of the 180° phase reversal of the current appearing at the Tx output with respect to the input Therefore, trans %) is achieved. Balanced resistance 40μ, yax input, and capacitor 30 and the resistor 28 is placed at the threshold between the ground point and the ground point. So that I can fill it up By choosing the value of the resistor to The return current from the Tx output generated by the injection current is passed through a 4Ω resistor from YBX. is canceled out by the current that flows.

The 11AG input of 5LIC10 performs analog ground comparison vh, and the common AC ground on the system power ground (poem deku de IB-) by setting the Noise #) Separate the four-wire reception and transmission signal paths. The hook status output H8O is the Along with other features, the providing an induced digital signal in response and providing an input signal at the FD1 input. , 5LIC10't'' to save power.

In addition to the above and other AC characteristics, 5LIC10 has It has several important characteristics. Therefore, the connection to terminals 12 and 14 is When a joined subscriber line loop is opened (as when the telephone is in an on-footer condition) , the 5LIC10 is in a static state (qsiaams%! stg te) Niroru. In this state current is supplied only through resistors 36 and 38. , power losses are mainly limited to leakage currents. Load applied to terminals 12 and 14 (for example, when the phone goes off-hook), sr, zc + a In a typical application, a DC current is applied to the line, i.e. the current is passed through transistor 20 or and a resistor 24. This current flows through the subscriber line loop through resistor 26 and and 5LIC10zc is returned through the transistor 22.

Furthermore, the DCM, which flows throughout the subscriber line roots, is 2 and 14, this voltage is detected and connected to the resistor 56 and the TSI input. and resistor 38, which changes the current flow (as %tflam) through the ESI input. will be replaced.

Current supplied from terminal 12 is drawn at terminal 14 (14%k) , terminal CC and transistor 20.22 and Chigg and operatively coupled to the ring current sense input TSI> and R3I The high gain compensation circuit within the 5LIC10, referred to as "C circuit", is a transistor 20.2 2, so that the DC intermediate of the subscriber line loop resistive load The point voltage is maintained somewhere between ground potential and yil (mcid-v).

Now, referring to Figure 2, the two-wire chip and ring terminal 102 are checked. and 104 to four wire unidirectional inputs at Tx and Rx inputs 106 and 108 Electronic termination that enables the use of 5LIC10'i as a termination device for signal conversion. An end device circuit 100 is illustrated. Therefore, both ends of the hybrid transformer 114 The two-way differential signal that appears is the line resistance symbolized by resistors 1102 and 112. is supplied between terminals 102 and 104 via. This signal is then 5LIC10 and appears at the TX output of 5LIC10 as a proportional single-ended signal. and received by the utilization means coupled thereto. Similarly, as mentioned above T’? The unidirectional AC signal applied to X is coupled to the Rx input of 5LIC10 and the ratio An example differential AC signal appears at terminals 1022 and 104.

(Parts in Figure 2 that correspond to the same parts in Figure 1 are referred to by the same numbers. . ) Although not shown, each of the two unidirectional signal paths "TX, i'RX" It is well understood that each one line forms a two-line pair that is matched with AC. be.

, termination circuit 100 can be used in numerous modem applications. For example, the speaker Since the horn can be coupled to terminals 106 and 108, the speaker can be coupled to terminal 108. will be combined. Next, connect the speaker horn microphone to all terminals 106, and Two-way voice communication can be carried out through all terminals IQO and the telephone system. Termination Another example of an application for the device 100 is to use all teletype equipment terminals 106 and 108. can be combined with

In the above-mentioned 5LIC10, the central office equipment uses all the subscriber interface circuits. It has been discovered that it cannot be easily connected to central office equipment as a terminating device when Ta. In many cases, when the central office equipment uses a subscriber interface circuit, , Due to the DC characteristics of 5LIC10, the central office 5LIC or the terminal device 5LIC has two Latched to one of the power rails: Unagi, thus the For this purpose, resistors 36 and 38 of V termination device 100 are arranged as shown in FIG. directly connected to the ring (AING) and tip (TIP) terminals, 5LI Connect C100 to the central office tip and ring terminals as shown in Figure 1. Assuming that the DC current is The terminal 100 is supplied to the chip terminal 102 for the register 22, and the termination device 100 DC current is provided to the ring terminal 104 for the LIC. Ideally, by phone The current supplied from the central office to the terminating device 100 is supplied to the terminating device 100 or to the central office equipment. The DC voltage between the tip and ring terminals is (Voo-YEg )/2 is equivalent to so. However, in reality, the telephone office 5LIC and the terminal The device 100 is matched against changes in ground potential, unbalanced subscriber line impedance and Due to other factors, the central office 5LIC and the termination equipment 100 may There may be a difference in the voltage that tends to concentrate on the ring terminal and the ring terminal.

This difference in DC voltage is then applied across the line (Xt%-) impedance, resulting in As a result, the compensation capacity of the 5LIC and the termination device 100C circuit exceeds the compensation capacity C@' LLE flow occurs. Therefore, one of the central office 5LIC and the terminal device 100 or both are driven to opposite power rails and this adversely affects their operation. .

From the above points, it is possible to separate the DC return of the shorted end device 100 from the total AC return path ρ. It was decided. Therefore 1. (C payment capacitors 1162 and 118 are ring and A respective sense resistor 56 and and 68. Therefore, 5LIC10 of the termination device 100 is a chip and In response to the AC differential signal appearing at the ring terminal, the signal at Tx is Generates a single-ended AC signal. However, the DC return path has the offset described above. This has been changed to prevent the issue from occurring.

As shown, the emitter of transistor 22 is now connected through current sensing resistor 120. 5LIC100EN terminal, but previously this was connected to the 5LIC100EN terminal as shown in The emitter of was returned directly to the HEN terminal. Therefore, the chip from the central office equipment The DC current supplied to terminal 102 is passed through transistor 22 and through resistor 120. Supplied. The current 151e passing through the resistor 120 is applied to the emitter of the transistor 122. and set the voltage. The current flow therethrough is determined by resistor 124. Transistor 122 has a collector returned to its base via resistor 126; Functioning as a well-known current mirror circuit, the direct voltage appearing at node 128 is resistive. 12(]7) is a function of the current passing through node 128 and transistor 162 (transistor 162). resistor 1 coupled between transistor 132 (matched to transistor 122) The value of 60 is equal to the value of resistor 126, and the emitter of transistor 162 has a value of 2 Emitter of voltage full transistor 122: 'K2? The voltage that can be applied is adjusted to the desired voltage.

Therefore, the current flowing through transistor 162 is between the emitter of transistor 132 and E. It is a function of the resistor 16401 connected between N and N. Size of resistor 134 By controlling the collector current supplied through the transistor 132, becomes proportional to the current supplied to the chip terminal 102. This is 5LIC1 All power supplies are formed at the TSI terminal 0. As mentioned above, the usury of 5LIC10 The gain internal C circuit is coupled to the R3I and TSI terminals, which connects the TRI and R3I Bias t'' changes for transistors 20 and 22 if the sense currents are not equal. let Therefore, the current provided by transistor 132 is 20 and 22 are adjusted such that resistors 124 and 166 are balanced. The currents passing through are equal, and the values of these resistors are 5LIC1 of the earth and the termination device 100. equals the value of the resistor 136 coupled between the R8I input and the R8I input. this state connects the DC current supplied from the transistor 20 to the ring terminal 104 to the central office equipment. The DC current supplied to the chip terminals is set equal to y, which is 0's 5LIC1a is floated to the DC equilibrium point of 5LIC10 of the central office. ) Capacitor 138 and resistor 130d DC feedback loose give. Furthermore, the resistor 40 in FIG. 1 is a series connected resistor 140. j42 (see figure 2) ), capacitor 40 is analog ground WAG and these two , along with resistors 562 and 68, coupled between the crossed nodes between the transistors of Find the appropriate AC loop termination device impedance.

For example, as Motorola's MC3419i 5LIC10 forming terminal device 100. When used, the gain of the internal C circuit is approximately 95, where resistor 134 is equal to resistor 1 That's 95 times more than 20.

The electronic termination circuit virtually described is an MC54j9 subscriber circuit with the following component values: This can be done using the loop interface circuit. Manufactured and tested.

Transistor 20 MJE 271 Transistor 22 MJE 270 Resistance 56 17.4f ohm Resistance 58 17.4f ohm Resistance 120 20 ohm Resistance 124 180f, t-A Resistance 126 20 O A Resistance 150 20 f ohm Resistance 134 1.9f ohm Resistance 136 180K ohm Capacitor 116 1.0sF j) / Denser 118 1. OsF j/densa 1382. ojF α National/international investigation report

Claims (1)

[Claims] 1. output at the first and second terminals in response to the differential signal supplied thereto. Generates a single-ended proportional signal in response to the force, and a signal conversion circuit for generating a proportional difference signal at the first and second terminals in response; road means and said signal conversion circuit means coupled to a full bidirectional signal path and a pair of two-wire unidirectional signal paths; and a direct current (DC) signal path is crossed between the two-way signal path and the signal conversion circuit means. A two-wire differential two-way signal that includes circuit means for separating from the current current (AC) signal path and metallization. An electronic termination circuit that performs signal conversion between a path and a pair of two-wire unidirectional signal paths. 2. The signal conversion circuit means is a subscriber line loop interface circuit (SLIC). 2. The electronic termination circuit of claim 1, comprising: t''. (5) The circuit means: C9 Detects the DC signal supplied from the two-way signal path and converts it into the DC'ti flow. a five-stream measuring means for setting a proportional pressure; b, coupled to the current detection means, an electric current a proportional to the detected DC"tL current; a means for generating a current mirror; , #5LIC is responsive to the current generated by the current mirror means, and W The circuit means M detects the DCg current t1 detected by the current detection means. The electronic termination of claim 2 which supplies a two-way signal path in which y is maintained equal to device circuit.