KR100285339B1 - Subscriber board in electronic switchboard - Google Patents

Abstract

The present invention is to provide a subscriber board that does not have a separate line concentrator in the exchange and the subscriber telephone period, so that the short-range subscriber as well as the remote subscriber can be accommodated by the exchange by using the same line, the maximum line resistance When the voltage determined in consideration is provided, a current limiting circuit is provided between the ring signal supply unit and the corresponding ring end to restrict the overcurrent from flowing in the tip resistor and the ring resistor when the corresponding tip / ring stage is shorted. A ring trip detection circuit that detects a DC voltage difference across both ends of the resistor R2 and detects a ring trip occurrence of the subscriber, and monitors the current change by a voltage difference across the tip resistor Rtip and the ring resistor Ring. Monitoring of voltage and current changes by outputting the result of detecting whether the subscriber is hooked off and whether the subscriber is a short-range or a long-range subscriber. , By controlling the voltage and current monitoring circuit changes the gain of the pulse code modulation data that is transmitted and received in the exchange and the subscriber call duration by the detection result output from the gain control circuit is configured to transport. Therefore, it is possible to increase the price competitiveness of the exchange when trying to accommodate distributed remote subscribers.

Description

Subscriber board in electronic switchboard

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a subscriber board in an electronic switch (hereinafter referred to as an exchange), and more particularly, to a subscriber board that can accommodate not only a short distance subscriber but also a long distance subscriber.

In general, a near field subscriber is a subscriber whose distance on the loop formed with the exchange is less than 2000 ohms, and a far-field subscriber is a subscriber whose distance on the exchange formed with the exchange is 4000 ohm up to more than 2000 ohms. However, since the voltage provided by the existing exchange is -48V, it does not satisfy the operating conditions of the remote subscriber whose line resistance is more than 2000 ohms, and the level of the voice signal transmitted / received is considerable because the line resistance is high as described above in the case of the remote subscriber. This attenuation prevents normal voice signal transmission.

That is, the subscriber boards provided for each channel in the existing exchanger flow through a ring resistor (Rring) connected to -48V and a tip resistor (Rtip) connected to 0V as shown in the subscriber board (100) shown in FIG. The current change detection unit 104 detects the change in the current to monitor the hook off state of the subscriber, and the PCM type applied through the tip (TIP0) / ring (RING0) of the channel 0 after being hooked off The audio signal is transmitted to the filter and codec 105 through the transformer TR, and the filter and codec 105 modulates the applied audio signal and transmits it to a digit detection (DTMF) device. At this time, when the loop formed between the exchange and the subscriber is a long line, although the above-mentioned telephone is in the hook-off state, the amount of the current change detected by the current change detection unit 104 is small and the hook-off state is completely absent. In addition to not recognizing, the level of PCM data output through the filter and codec 105 is also considerably reduced, resulting in a situation in which the digit detection of the PCM data received by the digit detection unit DTMF shown in the following stage is not properly detected.

Therefore, in the related art, a separate device such as a line concentrator is installed in a corresponding exchange and a subscriber's telephone period to accommodate a remote subscriber. However, line concentrators are useful when there are a large number of subscribers in the same area, but when a number of subscribers to be distributed are required, a number of line concentrators are required, which lowers the cost competitiveness due to burden on installation costs.

The present invention has been made in view of the above-described problem, and an object thereof is to provide a subscriber board that allows a switch to accommodate a remote subscriber without installing a separate concentrator.

Another object of the present invention is to provide a subscriber board that allows a switch to accommodate a short distance subscriber as well as a short distance subscriber.

In order to achieve the above object, an apparatus according to the present invention, a ring state signal supply unit for supplying a ring signal to the subscriber when receiving the subscriber status monitoring unit for monitoring the status of the subscriber for each channel and the pulse code transmitted and received in the exchange period with the subscriber In a switch matching process with a filter and a codec for filtering and modulating demodulation data, a DC voltage difference is detected between a ring end of a corresponding channel and both ends of a resistor existing between a ring signal supply unit. Ring trip detection circuit to notify subscriber status monitoring unit of ring trip occurrence when ring trip is detected for subscriber connected to channel; when the tip and ring ends of the corresponding channel are shorted, the voltage is provided in consideration of the maximum line resistance. A current limiting circuit for preventing overcurrent from flowing through the tip end resistor Rtip and the ring end resistor Rring; A transformer (TR) for supplying a voltage applied through a tip stage resistor (Rtip) and a ring stage resistor (Rring) to a corresponding subscriber line, and transmitting and receiving pulse code modulation data transmitted to and from the subscriber; Monitors the current change due to the voltage difference across the ring resistance and provides the subscriber status monitoring unit to check whether the subscriber is hooked off and outputs the result of determining whether the subscriber is a remote subscriber or a near subscriber. Supervisory circuits; The amplification gain of the pulse code modulation data transmitted and received between the transformer (TR), the filter and the codec is adjusted according to the result of determining whether the long-range or short-range subscriber transmitted from the voltage and current conversion monitoring circuit is transmitted, and the amplified pulse code modulation data is transmitted. And an impedance matching and gain control circuit for performing impedance matching between the transformer (TR), the filter, and the codec according to the reception.

1 is a detailed configuration diagram of an electronic switch having an existing subscriber board,

2 is a detailed configuration diagram of an electronic switch having a subscriber board according to the present invention,

FIG. 3 is a detailed circuit diagram of a ring trip detection circuit shown in FIG. 2;

4 is a detailed circuit diagram of the voltage and current change monitoring circuit shown in FIG.

FIG. 5 is a detailed circuit diagram of the impedance matching and gain control circuit shown in FIG.

<Explanation of symbols for main parts of drawing>

105: filter and codec 200, 210, 220: subscriber board

201: current limiting circuit 202: ring trip detection circuit

203: current and voltage change monitoring circuit 204: impedance matching and gain control circuit

301 and 303: low pass filter 302: DC voltage difference detector

304: first comparator 401: voltage difference detection unit

402: second comparator 403: third comparator

510: first impedance matching and gain control unit 520: anti-reflection unit

530: second impedance matching and gain control unit

Hereinafter, embodiments according to the present invention will be described in detail.

FIG. 2 is a detailed block diagram of an exchange having a subscriber board according to the present invention, illustrating the number of subscriber boards 200, 210, and 220 for each channel, and a hook-off state of a corresponding subscriber transmitted from each subscriber board 200 to 220. FIG. It consists of a subscriber status monitoring unit 130 to monitor and report to an ASIP (Analog Subscriber Interface Processor) not shown.

Each subscriber board 200 to 220 is configured as shown in the subscriber board 200 of FIG. 2. That is, the overcurrent protection unit 101 for preventing overcurrent from flowing on the tip line TIP0 when the phase transition (or phase shift) is induced, and the overcurrent protection unit 102 for preventing overcurrent from flowing on the ring line RING0. ) And an overvoltage protection unit 103 for protecting against overvoltage between the tip terminal TIP0 and the ring terminal RING0, and the relay R1 and the resistor R1 connected between the tip terminal TIP0 and the ground potential (0V). When the short-range subscriber is connected to the relay Rl2 and the resistor R2 connected to the external ring signal supply unit 230 and the ring terminal RING0, the overcurrent flows due to the supply voltage of -100V. A ring trip detection circuit 202 which detects a difference between the DC voltage across the current limiting circuit 201 and the resistor R2 to shut off, detects a ring trip, and transmits it to the subscriber status monitoring unit 130. ) And current change due to the voltage difference across the tip resistor (Rtip) and the ring resistor (Rring). The voltage and current change monitoring circuit 203 for detecting the hook on / off status of the subscriber and detecting whether the subscriber is a short-range or a long-distance subscriber and supplies the operating power of the subscriber's telephone through the subscriber line. Impedance matching and gain adjustment to adjust impedance matching and gain for PCM data transmitted and received through transformer TR according to the monitoring result transmitted from transformer TR and voltage and current change monitoring circuit 203 which perform transmission / reception processing And a filter and codec 105 for filtering and demodulating the PCM data transmitted and received from the circuit 204, the impedance matching and gain control circuit 204, or to the impedance matching and gain control circuit 204. Here, the overcurrent protection units 101 and 102, the overvoltage protection unit 103, the filter, and the codec 105 are the same as those provided in the existing subscriber board 100 shown in FIG.

The subscriber board 200 configured as described above is operated as follows.

First, the current limiting circuit 201 uses a transformer (TR) of -100V corresponding to twice the voltage provided by the existing exchange to satisfy the operating current of the remote subscriber telephone with the maximum line resistance of 4000 ohm. ) And the tip / ring end (TIP0 / RING0) to be supplied to the subscriber line to play a role to block the flow of over-current during the short (Short) between the tip / ring. A tip / ring short circuit occurs when the subscriber connected to the channel is a short-range subscriber. In order to play such a role, the current limiting circuit 201 uses a commercial IC that operates to maintain a minimum of 20 mA from 0 ohm to 4000 ohm based on a maximum line resistance of 4000 ohms and an internal feeding impedance of 1000 ohms.

As shown in FIG. 3, the ring trip detection circuit 202 includes a first low pass filter 301 and a first low pass to remove an AC component of a voltage applied to the resistor R2 of FIG. 2. A DC voltage difference detector 302 for detecting a DC voltage difference across the resistor R2 in the signal output from the filter 301, and a second component for removing the AC component from the DC voltage output from the DC voltage difference detector 302. And a first comparator 304 for outputting a ring trip detection signal by comparing the signal output from the low pass filter 302 and the second low pass filter 302 with a predetermined reference value Vref1, and a ring signal (20 Hz). 80Vms DC 48V superimposed) detects the ring trip state according to the hook-off of the subscriber telephone and notifies the subscriber status monitoring unit 130.

That is, the ring trip detection circuit 202 is a voltage across the resistor R2 shown in FIG. 2 in the first low pass filter 301 having the resistors R3, R4, R5 and capacitors C1, C2. After removing the AC component is transmitted to the DC voltage difference detector 302. The DC voltage difference detector 302 is configured of an amplifier AMP1 and detects only a DC component in a signal transmitted from the first low pass filter 301. At this time, the extracted DC component is a DC voltage difference across the resistor R2. The detected DC voltage difference is transmitted to the second low pass filter 303. The second low pass filter 303 has a structure of a resistor R10 and a capacitor C3 to remove the AC component that may be included in the DC voltage difference detected by the DC voltage difference detector 302. do. As described above, the DC voltage difference from which the AC removal operation is performed is transmitted to the first comparator 304. The first comparator 304 sets the reference value Vref1 to the minimum value of the ring trip (when the line resistance is 4000 ohms), and compares it with the DC voltage difference transmitted from the second low pass filter 303. As a result of the comparison, when the applied DC voltage difference is larger than the set minimum value, it is determined that the ring trip has been made, and the ring trip detection signal is transmitted to the subscriber state monitoring unit 130. As a result, the ASIP not shown interrupts the ring being generated to the subscriber's telephone.

The voltage and current change monitoring circuit 203 monitors the current change according to the voltage difference applied to the tip resistor Rtip and the ring resistor R201 according to the driving of the current limiting circuit 201, and corresponds to the hook-off state of the subscriber. As shown in FIG. 4, the voltage difference detector 401 and the second and third comparators 402 and 403 are configured to output a result of determining whether the subscriber is a remote subscriber or a near subscriber.

That is, the voltage difference detector 401 connects one input terminal to each one end of the tip resistor Rtip and the ring resistor Rring through the resistors R12 and R13, and connects the resistors R14 and R15 to each other end. It consists of an amplifier (AMP2) connected to the other input terminal through the detection of the voltage difference applied to the tip resistor (Rtip) and the ring resistor (Rring). The detected voltage difference is transmitted to the second comparator 402 and the third comparator 403, respectively. The second comparator 402 compares the applied voltage difference with a predetermined reference voltage Vref2 which is set to detect the hook-off state. At this time, the predetermined reference voltage (Vref2) is set to a voltage corresponding to 18mA so that when the line resistance is up to 4000ohm, the current is about 20mA so that if the 20mA or more can always be detected in the hook-off state. Therefore, when the voltage difference detected from the voltage difference detector 401 is equal to or greater than the reference voltage Vref2, the comparator COM2 outputs a signal indicating the hook-off state. The output signal is transmitted to the subscriber status monitoring unit 130 to maintain the hook-off state for the subscriber. Accordingly, the ASIP, not shown, recognizes that the subscriber connected to channel 0 hears the ringing and picks up the receiver.

On the other hand, the third comparator 403 outputs a result of determining whether the corresponding line resistance is more than 2000ohm or less in order to determine whether the subscriber is a short-range subscriber or a remote subscriber. To this end, since the feed voltage is -100V, the subscriber board 200 is designed to have a total of 1000 ohms including a transporter (TR) including a tip resistor (Rtip) and a ring resistor (Rring) and a DC resistance applied to the tip / ring end. The voltage corresponding to about 33 mA obtained by Equation 1 is set to the reference voltage Vref3 to operate.

Therefore, when the voltage difference transmitted from the voltage difference detector 401 is greater than or equal to the reference voltage Vref3, since the long distance subscriber whose line resistance is 2000 ohm or more, the CONT2 (Long Line mode) is output in the active state, and the applied voltage difference is When the reference voltage Vref3 is less than that, the comparison result is output such that CONT1 (normal line mode) is output in an active state because it is a short-range subscriber. CONT1 and CONT2 output from the third comparator 403 are provided as gain control signals of the impedance matching and gain control circuit 204.

Impedance matching and gain control circuit 204 is a first impedance matching and gain control unit as shown in Figure 5 to adjust the impedance matching and gain of the PCM data transmitted and received between the transformer (TR) and the filter and codec 105 510, an echo preventing unit 520, and a second impedance matching and gain adjusting unit 530.

The first impedance matching and gain adjusting unit 510 includes a first switch 511, a first resistor pad 512, a second resistor pad 513, a plurality of receiving amplifiers RX1 and RX2, and a plurality of load impedances. It consists of (Zo1) to adjust the impedance matching and gain for PCM data transmitted from the exchange side to the subscriber side. That is, the operation of the first switch 511 is controlled by CONT1 and CONT2 transmitted from the voltage and current change monitoring circuit 203. When the subscriber line connected to the corresponding channel is in the normal line mode, The first switch 511 is switched such that the first resistor pad 512 and the input terminal of the receiving amplifier RX1 are connected. When the subscriber line is in a long line mode, the first switch 511 is connected to the second switch. The resistance pad 513 and the input terminal of the receiving amplifier RX1 are switched to be connected. To this end, the first switch 511 is implemented as an analog switch.

When the first resistance pad 512 is connected, the value of the first resistance pad 512 is set to a value smaller than that of the second resistance pad 513 so that the gain of the receiving amplifier RX1 is suitable for the short-range subscriber line. In this case, the gain has a smaller value than when the second resistance pad 513 to be described later is connected. When the second resistor pad 512 is connected, the second resistor pad 513 is set to a larger value than the first resistor pad 512, so that the gain of the receiving amplifier RX1 is increased by the first resistor pad 512. ) Is increased than when connected. The receiving amplifier RX1 whose gain is adjusted in this way amplifies a predetermined value of PCM data transmitted from an unshown receiving amplifier RX AMP included in the filter and the codec 105 (also called a combo). And transmit to the load impedance Zo1 and the next receiving amplifier RX2, respectively. The load impedance Zo1 transmits the PCM data transmitted from the receiving amplifier RX1 to the transformer TR by matching the impedance with one line of the transformer TR having a two-wire structure. The receiving amplifier RX2 amplifies the PCM data transmitted from the receiving amplifier RX1 by a predetermined value and transmits it to the load impedance Zo1. The load impedance Zo1 matches the impedance of the PCM data applied with the load impedance Zo1 described above with the other side of the transformer TR and transmits the impedance to the transformer TR.

The anti-reflection unit 520 includes an amplifier TBRL, a second switch 521, a third resistor pad 522, a fourth resistor pad 523, and resistors R22, R23, R24, and R30. As described above, during reception processing, the received voice signal is prevented from being echoed to the filter and codec 105 side. That is, when the same CONT1 and CONT2 signals are applied to the first impedance matching and gain control unit 510 described above, the second switch 521 operates in the same way as the first switch 511 described above. Adjust the gain of TBRL). The signal and phase output from the second impedance matching and gain control unit 530, which will be described later, are converted to the PCM data output from the reception amplifier RX AMP included in the filter and the codec 105 with the gain adjusted as described above. The amplified signal is amplified so as to be output as the same signal, thereby preventing the received PCM data from being reflected to the filter and codec 105 side. At this time, the signal output from the second impedance matching and gain control unit 530 is transmitted to the amplifier TBRL output terminal through the resistor R30.

The second impedance matching and gain control unit 530 is switched by the amplifier TX, the bias resistors R25, R26, R27, and R28 of the amplifier TX, and the third switch 531 which is switched by the above-described CONT1 and CONT2. The input impedance of the PCM data, which is composed of the resistor R29 and applied to the filter and the codec 105, is changed. That is, in a short distance, the third switch may allow the resistor R29 to intervene in the transmission path formed between the output terminal of the transmitting amplifier TX and the input terminal of the filter and the not-shown transmitting terminal TX of the codec 105. 531 is operated. As a result, the input resistance of the transmitting end TX of the filter and the codec 105 increases, so that the gain of the transmitting end TX of the filter and the codec 105 is relatively reduced. In the case of a long distance, the third switch 531 is switched so that only the resistor R28 is connected to the corresponding transmission path, thereby reducing the input resistance of the filter and the codec 105 to increase the gain of the transmitter TX.

As described above, the present invention implements a plurality of line concentrators as in the prior art by implementing the service on the same line for a short distance subscriber as well as a remote subscriber using only a subscriber board provided at the exchanger without providing a separate line concentrator. There is no need to install a relatively effective price competitiveness can be increased. This effect can be greater if the far-field subscribers to be accommodated are dispersed.

Claims (4)

Filtering and modulation / modulation of the subscriber status monitoring unit 130 for monitoring the status of the subscriber for each channel and the ring signal supply unit 230 for supplying the ring signal to the subscriber when receiving and the pulse code modulation data transmitted / received during the exchange with the subscriber. In the switch having a filter and codec 105 to perform the subscriber matching processing, When a ring trip is detected for a subscriber connected to the corresponding channel by detecting a DC voltage difference between both ends of a ring of the corresponding channel and a resistance R2 existing between the ring signal supply unit, the ring is transmitted to the subscriber state monitoring unit 130. A ring trip detection circuit 202 for informing a trip occurrence; When the tip and ring ends of the channel are short-circuited, the current limiting circuit 201 prevents overcurrent from flowing to the tip and ring resistances by the voltage provided in consideration of the maximum line resistance. ); A transformer (TR) for supplying the voltage applied through the tip stage resistor (Rtip) and the ring stage resistor (Rring) to the subscriber line, and transmitting and receiving the pulse code modulation data transmitted during the exchange period with the subscriber; By monitoring the current change due to the voltage difference across the tip resistance (Rtip) and the ring resistance (Rring), whether or not to hook off the subscriber is provided to the subscriber status monitoring unit 130, and whether the subscriber is a remote subscriber A voltage and current change monitoring circuit for outputting a result of determining whether the subscriber is a subscriber; Amplification gain of the pulse code modulation data transmitted / received between the transformer TR and the filter and the codec 105 according to a result of determining whether the remote subscriber or the short-range subscriber transmitted from the voltage and current change monitoring circuit 203 is determined. And an impedance matching and gain control circuit 204 for adjusting impedance and performing impedance matching between the transformer TR, the filter, and the codec 105 according to transmission and reception of the amplified pulse code modulation data. Subscriber board. 2. The subscriber station of claim 1, wherein the ring trip detection circuit 202 includes a first comparator for detecting whether the ring trip is generated by comparing the DC voltage difference with the ring trip detection value at the maximum line resistance. board. The method of claim 1, wherein the voltage and current change monitoring circuit 203 detects whether the hook is turned off by comparing the voltage difference with a voltage corresponding to a current lower than the current at the maximum line resistance. The comparator and the voltage difference are compared with the voltage corresponding to the current obtained by dividing the voltage provided by considering the maximum line resistance at the exchange by the sum of the total resistance value in the subscriber board and the maximum line resistance value corresponding to the short-range subscriber. And a third comparator for outputting a result signal of determining whether the subscriber is a remote subscriber or a near subscriber. [4] The pulse code modulation of claim 3, wherein the impedance matching and gain control circuit 204 adjusts a resistance value on a line by a switch which is switched by a signal output from the third comparator and is transmitted from the exchange to a corresponding subscriber. Receiving amplifier for adjusting the gain of the data, the resistance on the line is adjusted by a switch switched by the signal output from the third comparator to adjust the gain of the pulse code modulation data transmitted from the subscriber to the exchange An inverted signal having the same magnitude as that of the output of the transmitting amplifier, the level of the pulse code modulation data output from the filter and the codec 105 to prevent the transmitting amplifier and the received pulse code modulation data from being echoed to the exchange side. Echo amplifier with amplification and output Subscriber board comprising.