JPH1032848A - Bnw optimization system for exchange subscriber circuit using sublt period - Google Patents

Abstract

PROBLEM TO BE SOLVED: To automatically set a BNW(balancing network) in a short time by transmitting a white noise, measuring the wraparound signal value and optimizing the BNW, so as to minimize the wraparound by the control of a control circuit. SOLUTION: If a special number is transmitted from a subscriber terminal A, an internal relay 103 of a subscriber circuit 1 connected to the terminal A via a two-wire interface is connected to a BNW control subscriber circuit 2. Then a CPU 8 transmits a signal to the circuit 2 from a white noise transmitting circuit 4 via a control bus 10, and the wraparound signal is received by a white noise receiving circuit 5 and a power spectrum is calculated. At the same time, several types of BNW are set, and the BNW value with which the spectrum is minimized is stored in a memory 9. Finally, a tone which serves as an end sign is sent to the terminal A from a tone SND 6, via the circuit 2, finishing the setting operation. Thus, the effect is enhanced particularly for the attachment construction for a new subscriber circuit, etc.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a balancing circuit ("BN") for a subscriber circuit connected to a subscriber terminal by two wires.
W ") is automatically optimized in a short time, and in particular, a local switch (Local Switch)
h) BNW adjustment method applied to (referred to as “LS”).

[0002]

2. Description of the Related Art For example, as a conventional method of adjusting a balancing net of a 2-wire to 4-wire conversion unit for suppressing a sneak signal caused by impedance mismatch in a 2-wire to 4-wire conversion unit of a communication line interface unit. Japanese Unexamined Patent Publication No. Hei 5-328417 discloses a private branch exchange (Private exchange) that can easily and surely perform a balancing net adjustment of a 2-wire to 4-wire conversion unit in a 2-wire analog communication line interface unit. PB
X) by providing a test signal generating section for generating a test signal such as white noise used for adjusting a balancing net in a control section for performing the call control processing of X) or a 2-wire analog communication line interface section. A method has been proposed in which the balancing net of the 2-wire to 4-wire converter in the 2-wire analog communication line interface is adjusted using a test signal output from the generator. Japanese Unexamined Patent Publication No. 3-85852 discloses a method of independently diagnosing the communication path of a subscriber circuit by independently diagnosing the communication path in each direction between the subscriber terminal of the subscriber circuit and the inside of the exchange. Have been proposed.

Conventionally, there is no timing for setting an optimum BNW for a subscriber circuit, several types of BNW values are prepared, a standard value is determined from the values, and the value is uniformly set for all the subscriber circuits. And so on.

[0004] Alternatively, a call is transmitted from the subscriber terminal A to be received by the subscriber terminal B, and white noise is input from the transmitter of the subscriber terminal A by an external white noise generator.
There is also a method of adjusting the BNW of the subscriber circuit of the subscriber terminal B while listening to the looping sound from the receiver of the subscriber terminal A.

Further, a white noise generator and its control unit are built in the PBX, and after a call is transmitted from extension A and received at extension B, the extension operation on the extension B side is performed by the extension A.
There is also a method in which the side performs a white noise transmission request operation on the extension B side, and adjusts so that the BNW becomes optimal while listening to the incoming call from the receiver on the extension A.

[0006]

The above conventional method has the following problems.

[0007] The first problem is that in the case of setting the standard value, a line in which the BNW value is not appropriate and the roundabout increases appears, and the service quality is not uniform.

[0008] The second problem is that, in the method of listening to the incoming call from the receiver of the subscriber terminal A, the work of carrying the external white noise generator is complicated. There was ambiguity in the adjustment method.

The third problem is that, in the case of PBX, since the operation is a transmission / reception operation between extensions, it is difficult to apply it to a subscriber connected to an exchange such as an LS. Further, the special key operation such as white noise transmission complicates the adjustment work.

SUMMARY OF THE INVENTION Accordingly, the present invention has been made in view of the above circumstances, and has as its object to realize high-speed operation by automatically adjusting a BNW simply by transmitting a special number from a subscriber terminal, thereby realizing high-speed white noise. BNW can be set quantitatively by taking advantage of the above, improving the reliability. In addition, by sending a special number and receiving the signal to complete the BNW setting, the setting is completed, thereby improving the operability and maintainability. Balancing net adjustment It is to provide a method.

[0011]

In order to achieve the above object, a system according to the present invention comprises a telephone switching subscriber circuit for interfacing with a subscriber telephone by a two-wire to four-wire conversion circuit having a balancing network; In a test procedure of a telephone test having a transmitting circuit, a receiving circuit, and a control circuit, and notifying the telephone exchange of a special number from the telephone, the white noise transmitting circuit is configured to output white from the 4-wire side during off-hook of the telephone. Transmitting the noise, measuring the amount of sneak signal to the other of the four wires by the reception circuit, and optimizing a balancing net (BNW) so that the sneak signal amount is minimized under the control of the control circuit. It is characterized by that.

The present invention provides an LS (Local Switch) having a white noise generating circuit used for adjusting a balancing net, a receiving circuit therefor, and a control unit for them.
h), a hybrid (Hybr) whose BNW value is to be adjusted
id) A special number is transmitted from the subscriber terminal connected to the circuit, and the BNW can be automatically adjusted by adjusting the white noise wraparound.

[0013]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a diagram showing a configuration of an embodiment of the present invention, and is a block diagram showing a configuration of a local switch (LS).

Referring to FIG. 1, the LS main body includes a subscriber circuit (LC) 1 and a subscriber circuit (LC) 2 (however, the subscriber circuit 2 may have the same configuration as the subscriber circuit 1). , Switch (SW) 3, white noise transmission circuit 4, white noise reception circuit 5, and tone transmission circuit (tone S
ND) 6, a tone receiving circuit (tone REC) 7, a central processing unit (CPU) 8, a memory 9, a white noise transmitting circuit 4, a white noise receiving circuit 5, a tone SND 6, and a tone REC 7. Control bus 1
0-13 are provided.

It is assumed that a special number is transmitted from the subscriber terminal A. The internal relay 103 of the subscriber circuit 1 connected to the subscriber terminal A by a two-wire interface is connected to the BNW adjustment subscriber circuit 2.
Connected to

Thereafter, a signal is transmitted from the CPU 8 from the control bus 10 to the subscriber circuit 2 from the white noise transmitting circuit 4, and the wraparound signal is received by the white noise receiving circuit 5 to calculate a power density spectrum. At this time, several types of BNWs are set, and the BNW value that minimizes the spectrum is stored in the memory 9.

Finally, a tone which is an end signal from the tone SND6 is transmitted to the subscriber terminal A via the subscriber circuit 2, and the setting is completed.

FIG. 2 shows a BN according to an embodiment of the present invention.
It is a flowchart for demonstrating a W setting procedure.

When a special number is transmitted from the subscriber terminal, the subscriber terminal is connected to the BNW setting subscriber circuit and transmits white noise.

During the transmission of white noise, in FIG. 2, the BNW value is C (Compromise: medium impedance), the BNW value is L (Loaded: high impedance), the BNW value is N (Non-Loaded: low impedance), The BNW value is set to T (Test: in the case of the own station building), and the BNW value is set and the power spectrum of the wraparound signal is measured.

Then, the set value that has become the minimum spectrum is stored, the setting is completed, the white noise transmission is stopped, and the tone of the end signal is transmitted to the subscriber terminal. In addition,
The power density spectrum measurement is performed as follows.

The average power P of the white noise h (t) is given by the following equation (1).

[0023]

(Equation 1)

The 4-wire side of the hybrid circuit 101
Since it is PCM (digital) of law or a-law, the average power is represented by the following equation (2).

[0025]

(Equation 2)

However, since the inside of the exchange is a signal sampled at a sampling frequency fs = 8000 Hz (8 kHz), even if white noise is transmitted, there is actually only a power density spectrum band up to 4000 Hz (= fs / 2). .

For this reason, adjustment is made so that the average power up to 4000 Hz is minimized. Alternatively, the power density spectrum of the white noise is equal at all frequencies up to about 10 ¹³ Hz (the spectrum is flat).
It is also possible to take the power density spectrum of kHz and set it to be the minimum.

In the above embodiment of the present invention, a subscriber circuit is provided for transmitting white noise. However, as another embodiment, as shown in FIG. 3, for example, as shown in FIG. It is also possible to make adjustments using a user circuit.

Further, as another embodiment, a transmission circuit may be used in which a path is set by the switch SW3 and the white noise tone is continuously transmitted without being controlled by the control buses 10 to 13.

In the present invention, the adjustment in combination with another line test (subscriber line test; SubLT: Subscribe)
r Line Test) is the most efficient.

As one embodiment of the present invention, a procedure for performing BNW adjustment in combination with another line test will be described with reference to FIG.

When the subscriber terminal is off-hook (Off Hoo
k) and adjust (Subscriber Line T)
est) (step S20).

Upon recognizing the special number, the switching software shifts from the call monitoring state to the non-monitoring state for the subscriber (subscriber) who turned the special number (step S21).

The subscriber line (subscriber line) is drawn into a test link (test link) to which a measuring device for line measurement is connected (step S2).
2).

When the pull-in is completed, the subscriber who has turned the special number is informed of a dial tone (Dial Tone) as a signal of completion of preparation (step S24).
However, at the previous timing, the BNW described in the above embodiment is adjusted (step S23).

When the subscriber hears the dial tone, the subscriber goes on hook (On Hoo).
k) (Step S25), on-hook (On H)
(OK) as a signal to measure line parameters (resistance,
(Eg, capacitance) (step S26).

When the measurement is completed, the subscriber is ringed to notify the result.
The transmission is made off-hook (Off Hook) (step S27), and the result is notified by two types of tones as to whether the result is OK or NG (step S2).
9).

If the result is OK, a telephone test is subsequently performed (step S32). At this time, a predetermined number is dialed.

Whether the result is OK or NG is notified by two types of tones (step S3).
4).

The process is terminated after the on-hook operation (On Hook) (step S35).

[0041]

As described above, according to the BNW setting method for the subscriber's circuit of the present invention, white noise is automatically transmitted by transmitting a special number from the subscriber terminal, and the BNW is automatically transmitted in a short time. There is an effect that the setting can be made, and the characteristic effect is large particularly when a new subscriber line is installed.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a circuit connection configuration according to an embodiment of the present invention.

FIG. 2 is a flowchart showing a BNW setting procedure according to the embodiment of the present invention.

FIG. 3 is a diagram for explaining another embodiment of the present invention, and is a block diagram in a case where a BNW setting subscriber circuit is not provided and transmission control is not required for white noise transmission and tone transmission.

FIG. 4 is a diagram for explaining an embodiment of the present invention, and is a flowchart when combined with another line test.

[Explanation of symbols]

 1, 2 subscriber circuit 3 switch 4 white noise transmission circuit 5 white noise reception circuit 6 tone transmission circuit (tone SND) 7 tone reception circuit (tone REC) 8 central processing unit (CPU) 9 memory 10, 11, 12, 13 Control bus

Claims (2)

[Claims] 1. Two wires 4 with balancing network
A telephone switching subscriber circuit that interfaces with a subscriber telephone by a line conversion circuit, a white noise transmitting circuit, a receiving circuit, and a control circuit, and a telephone test is performed by notifying the telephone exchange of a special number from the telephone. In the test procedure, while the telephone is off-hook, the white noise transmitting circuit transmits white noise from the 4-wire side, the receiving circuit measures the amount of sneak signal to the other of the four wires, and wraps around under the control of the control circuit. A BNW optimization method for an exchange subscriber circuit, characterized in that a balancing net (BNW) is optimized so that a signal amount is minimized. 2. A special number is transmitted from one subscriber terminal connected to a subscriber circuit to be adjusted for a balancing net, and a white noise transmitting means is connected to the subscriber terminal so as to be connected to a 4-wire receiving path of the terminal. Transmits white noise, measures the power spectrum by connecting the 4-wire side transmission path to the white noise receiving means, and varies several types of balancing net values to detect the balancing net value that minimizes the measured power spectrum. And setting the balancing net value for the subscriber terminal. BNW optimization method for an exchange subscriber circuit.