KR0148410B1 - Apparatus for improving call quality in matching keyphone system and telephone - Google Patents

Abstract

The present invention relates to a method for adjusting impedance matching and gain between a keyphone main device and a general telephone when making a call using a general telephone in a keyphone system to obtain an optimal call characteristic in a call state. In this case, the main device of the key-phone system supplies an operating power supply and a ring signal to a general telephone, and recognizes a dial (DP: Digital pulse or DTMF: Dual tone multi frequency) signal transmitted from the general telephone. To perform various matters such as call state and call recovery, and to detect current flowing through the feeding circuit unit 20 'connected to the surge protection unit 10 between the resistor R4 and the resistor R7. Feeding circuit detection unit 40 is configured by connecting the coupler (PC1), and the communication current control unit 50 'for controlling the signal sensed by the feeding circuit detection unit 40 to improve the call characteristics that It characterized.

Description

Device that improves call characteristics when matching key phone system and regular telephone

1 is an internal circuit diagram of a key phone system matched with a conventional general telephone.

2 is an internal circuit diagram of a key phone system matched with a general telephone of the present invention.

* Explanation of symbols for main parts of the drawings

1: general telephone 2: surge protection unit

20,20 ': feeding circuit part 30: response detecting part

40: feeding circuit detection unit 50,50 ': talk current control unit

70: central processing unit control unit

RL1, RL2: Relay switch (Relay S / W)

PC1, PC2: Photo coupler

SW1, SW2, SW3, SW4: Multiplexer

The present invention relates to a method for adjusting impedance matching and gain between a keyphone main device and a general telephone when making a call using a general telephone in a keyphone system to obtain an optimal call characteristic in a call state. In this case, the main device of the key-phone system supplies an operating power supply and a ring signal to a general telephone, and recognizes a dial (DP: Digital pulse or DTMF: Dual tone multi frequency) signal transmitted from the general telephone. To perform various matters such as call status and call recovery.

Conventionally, circuit design costs are high due to circuit design using a subscriber line interface (SLIC) integrated circuit (PBX) in a private branch exchange (PBX) or a private exchange (PABX). In most keyphone systems, it is common to design low cost using separate different components.

In general, the key-phone system is designed to fix impedance matching and the loop current, which is a variable of impedance and handset gain, is a key factor when making calls using a general telephone. The lack of consideration of the characteristics of the phone and the conditions of use often caused quality dissatisfaction.In addition, sidetones were generated due to the lack of technology to improve the call characteristics by detecting loop current in the phone main station internal circuit. There was a problem that the currency sensitivity fell.

The conventional general telephone matching circuit diagram described above can be represented as shown in FIG. 1, where a general telephone is connected between (T) and (R), which are telephone terminals, which are ring signals from a power supply of a keyphone main unit. Is connected to the first relay switch (RL1) for ring signal control to control the ring signal by the switch terminal contact and is connected to a surge protection part 10 for limiting surge introduced from the outside during a call. A feeding circuit unit 20 for receiving a signal output from the surge protection unit 10 to determine whether a subscriber of the general telephone 1 is received, and a transformer to control a call current passing through the feeding circuit unit 20. And a signal output from the talk current controller 50 and the talk current controller 50 configured to be connected in series and in parallel in order to compare and subtract the input current. Well The central processing unit controller 70 for detecting a handset state and controlling the ring signal by the voice signal conversion unit 60 that converts the signal into a signal and the response detector 30 including the resistor R13 and the photo coupler PC2. It is composed.

As described above, the conventional matching circuit does not sense the current flowing through the feeding circuit unit 20, so that the loop current is fixed to an arbitrary value, and thus, the communication characteristics are not good.

In order to compensate for this problem, the present invention has the characteristics of keeping the call characteristics good by compensating for low call sensitivity when using long distance lines by adjusting impedance matching by sensing loop current during a call and adjusting call gain. To make it possible.

A keyphone system having such a characteristic can be shown as shown in FIG. 2, where the general telephone 1 is connected between the (T) and (R) lines of the main station internal circuit, and the ring in the power supply of the keyphone main unit (not shown) is shown. A ring control first relay switch RL1 for receiving a signal and switching to apply a ring signal to a terminal of a switch terminal, a surge protection unit 10 for limiting surge input from the outside during a call, and the surge protection unit ( When the voice signal is generated by the talk current control unit 50 'connected to the transformer T1 through the feeding circuit unit 20' connected to 10) and the talk current control unit 50 ', the response signal is detected even during ring supply. To this end, the response sensing unit 30 composed of a second photocoupler (PC2) and the resistor (R13), the central processing unit controller 70 for sensing the handset state of the response sensing unit 30, and the feeding Detect the current flowing through the circuit portion 20 ' In order to send a signal to the voice signal control unit 60, the feeding circuit detection unit 40 and the feeding circuit detection unit configured by connecting the first photocoupler (PC1) between the resistor (R4) and the resistor (R7) In order to control the signal sensed by 40 to improve call characteristics, the voice signal call control unit 50 'composed of four multiplexers SW1-SW4, and the output signal of the feeding circuit unit 20' It is composed of a central processing unit control unit 70 for receiving the input and controlling the circuit.

In the key phone system configured as described above, when the general phone 1 is called, if the ring output provided from the key phone main device is applied to the terminals 2 and 4 of the first relay switch RL1 through the resistor R3, the general phone 1 Ring current flows through the feeding circuit unit 20 'so that the bell rings, and terminals 7 and 5 are connected to the second relay switch RL2.

At the same time, the resistor R9 and the photocoupler PC2 detect the feeding circuit unit 20 'in parallel with the resistor R7 to detect the response signal while the ring is being supplied.

In addition, when the user of the general telephone 1 picks up the handset to make a call, an external +24 V is supplied through the resistor R7, whereby the transistor Q1 is turned on so that a current flows in the general telephone 1.

Then, the first relay switch RL1 connects the terminals 2 and 3, and the bias current of the transistor Q1 becomes a forward bias and flows through the resistor R5 to the diode D1.

As described above, when terminals 2 and 3 of the first relay switch RL1 are connected, they are applied to the base of the transistor Q2 via the resistor R8 through the diode D2, and thus, the transistor Q2 is forwarded to the transistor Q2. A bias is applied and turned on.

In addition, when the contacts 7 and 6 of the relay switch RL2 connected in parallel with the resistor R7 are turned on, the call current is applied to the second photocoupler PC2 to detect a call state. When the phone is busy, the output signal of the second photocoupler PC2 is at a low level, and at an idle time, the output signal is at a high level.

Therefore, the dial pulse digit signal transmitted from the general telephone 1 is also recognized through the second photo coupler PC2.

In addition, the talk current changes due to the resistance (R) of the call signal depending on the call condition (short distance / long distance). In order to detect the change in the talk current and adjust impedance matching and handset gain, The resistors R7 and R4 and the first photocoupler PC1 are used to sense the loop current.

In this case, the output signal level of the first photocoupler PC1 becomes low in the short distance, and the output signal level becomes high in the long distance. do.)

In order to match the impedance with the output signal of the first photocoupler PC1 when the talk current is sensed in the call state, the resistor R21 and the resistor R22 are connected in parallel with the analog multiplexer SW1 and used for the call gain Connect resistor R27 and resistor R28 in parallel with multiplexer SW3, connect resistor R29 and resistor R30 in parallel with multiplexer SW4 for hand gain adjustment, and adjust impedance Z1) and impedance Z2 are connected in parallel with the multiplexer SW2.

In this case, the short-range matching impedance is set to 600 Ω, 750 Ω at long range, and 0 dB at close range and +3 dB at long range.

In addition, the termination impedance = resistance (R20) + resistance (R21) + resistance (R22) + internal multiplexer (R) of the analog multiplexer (SW1) is determined by the sum.When the line is remote, the signal resistance increases and the talk current decreases. As a result, the first photo coupler PC1 senses a loop current to improve communication characteristics.

As described above, in the case where the general telephone 1 is connected and used in the key parking lot, the call sensitivity is low because the impedance matching and the handset gain are not adjusted according to the preferred distance. The present invention has a disadvantage in that the circuit ratio slightly increases as compared with the past, but it is an invention that can maintain the sensitivity and sidetone state of the call characteristics when using a long distance line.

Claims (3)

A general telephone (1) connected between the terminals (T) and (R), a ring signal control first relay switch (RL1) for receiving a ring signal from a keyphone main unit and controlling the ring signal by a switch terminal contact, A surge protection unit 10 for limiting surges introduced from the outside during the operation, a response detection unit 30 composed of a second photocoupler PC2 for detecting a response signal even during ring supply, and the response detection unit ( In the device for improving the call characteristics when matching the phone and the phone system consisting of the central processing unit control unit 70 for controlling the detection of the handset in 30, the feeding circuit unit is connected to the surge protection unit 10 A feeding circuit detector 40 configured to connect a first photocoupler PC1 between the resistor R4 and the resistor R7 to sense a current flowing through the 20 ', and the feeding circuit detector 40 Increase the call characteristics by controlling the detected signal When the phone system, characterized in that it is composed of a call current controller (50) for matching to the standard telephone apparatus that can improve the call attributes. The telephone call system of claim 1, wherein the call current controller 50 'comprises four multiplexers (SW1), (SW2), (SW3), and (SW4). Device that improves characteristics. The method of claim 2, wherein the multiplexer (SW1) is connected in parallel to the resistor (R21) and the resistor (R22) in order to match the impedance of the output signal of the first photocoupler (PC1) which is the talk current sensed in the call state, The multiplex SW3 connects the resistor R27 and the resistor R28 in parallel for the transmission gain, and the multiplexer SW4 connects the resistor R29 and the resistor R30 in parallel for the gain adjustment. The multiplexer (SW2) connects the impedance (Z1) and the impedance (Z2) in parallel for sidetone control, thereby simultaneously controlling four analog multiplexes (SW1-SW4). Device that improves characteristics.