JPS644381B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a hybrid circuit adjustment method and apparatus for adjusting circuit constants of a balanced circuit in a hybrid circuit that connects a four-wire line and a two-wire line.

[Prior art]

There are two types of telephone lines: four-wire lines and two-wire lines.
Examples of four-wire lines include lines for carrier telephone equipment having a sending line and a receiving line, and examples of two-wire lines include lines for telephone exchanges. These four-wire line and two-wire line are connected by a hybrid circuit. This hybrid circuit is provided with a balance circuit to balance the impedance with the two-wire line. However, since the impedance of a line varies depending on the connection state of the line, the number of telephones connected to the line, and the usage conditions of these telephones, it is not possible to always balance the impedance with a balanced circuit. If the impedances are not balanced, the signal from the transmitting line is sent to the receiving line, and if the amplification in the carrier telephone device is large, a problem arises in that a ringing sound is generated. Although ringing can be prevented by reducing the amplification in the carrier telephone device, when a four-wire line and a two-wire line are connected, the hybrid circuit causes speech attenuation, which is a problem.

[Purpose of the invention]

The present invention was made in consideration of the above circumstances, and
It is an object of the present invention to provide a method and device for adjusting a hybrid circuit that can always balance impedance and that does not generate noise even if a signal is amplified.

[Summary of the invention]

In order to achieve the above object, the present invention inputs an adjustment pulse to the transmitting line, measures the response waveform appearing on the receiving line, compares this response waveform with a plurality of standard waveforms, and selects the closest standard waveform. However, the circuit constants of the balanced circuit are set to the circuit constant values corresponding to this standard waveform.

This allows the balance circuit to be adjusted according to the actual impedance of the line, so that no ringing occurs even when the signal is amplified.

[Embodiments of the invention]

A hybrid circuit adjustment device according to an embodiment of the present invention is shown in FIG. A hybrid circuit HB is provided to connect a four-wire line 4W having a sending line 4WS and a receiving line 4WR to a two-wire line 2W. The transmission line 4WS is connected to the primary coil of the transformer T1. This transformer T
One end of the secondary coil No. 1 is grounded, and the other end is connected to the input end of the amplifier A1 via a switch SW. Further, a 600Ω resistor R1 is connected between the other end of the secondary coil of the transformer T1 and the ground. The switch SW is used to select whether to input a transmitting signal or an adjustment pulse to be described later to the amplifier A1. The output terminal of amplifier A1 is
It is connected to one end of the primary coil of the transformer T3 via a 600Ω resistor R3. The other end of this primary coil is grounded. A two-wire line 2W is connected to the secondary coil of the transformer T3.
One end of the primary coil of the transformer T3 is also connected to the positive input end of the amplifier A2. The output terminal of amplifier A2 is connected to transformer T2 via a 600Ω resistor R2.
is connected to one end of the primary coil. The other end of this primary coil is grounded. transformer T
A receiving line 4WR of a four-wire line 4W is connected to the secondary coil 2.

A balance circuit N for balancing the impedances of the four-wire line 4W and the two-wire line 2W is provided in the hybrid circuit HB. This balanced circuit N is composed of impedances Z1 and Z2 connected in series. An impedance Z1 is inserted between the input terminal of amplifier A1, which amplifies the transmitting signal, and the negative input terminal of amplifier A2, which amplifies the received signal, to correct the R component and the L component of the two-wire line. .
Further, an impedance Z2 is inserted between the negative input terminal of the amplifier A2 and the ground, and performs correction of the R component and the C component of the two-wire line. The detailed configuration of the balanced circuit N is as shown in FIG. 2a, and is modeled on a two-wire line that is a distributed constant circuit. That is, the impedance Z1 has a resistor R11, a capacitor C13 connected in series, and a resistor R13 connected in parallel, and the impedance Z2 has a resistor R21 connected in series with a capacitor C22 and a resistor R22 connected in series. Capacitor C23
and resistor R23 are connected in parallel. These resistors R11, R12, R13, R21, R22, R
23 and capacitors C12, C13, C22, C2
3, it is possible to change the circuit constants by setting output from the adjustment device 10, which will be described later. For example, the resistor may be composed of a variable resistance element, or a plurality of resistors may be switched using a switch. The same applies to capacitors. In addition, as shown in Fig. 2b, capacitors C12 and C13, resistor R1
2, R13, capacitor C22, C23, resistor R
22 and R23 may be combined into a capacitor C14, a resistor R14, a capacitor CC24, and a resistor R24.

In order to adjust the circuit constants of the balance circuit N, an adjustment device 10 is provided. This adjustment device 10 is
a start input terminal for starting the adjustment by this adjustment circuit; a pulse output terminal for outputting the adjustment pulse;
It has a waveform input terminal for inputting a response waveform of the adjustment pulse on the receiving line side, and a setting output terminal for setting circuit constant values of the balance circuit N. The pulse output terminal is connected to the switch SW, the waveform input terminal is connected to the positive input terminal of the amplifier A2 on the receiving line side, and the setting output terminal is connected to each impedance Z1, Z2 of the balanced circuit N.

Pulse generation circuit 22 connected to the start input terminal
is a circuit that generates adjustment pulses, and the generated adjustment pulses are output from the pulse output terminal. A measuring section 12 is connected to the waveform input terminal. This measuring section 12 measures the response waveform of the receiving line in response to the adjustment pulse. For example, the voltage value at each phase of the response waveform is measured. On the other hand, the standard waveform memory 16
A typical response waveform is stored as a standard waveform. Circuit constant values corresponding to these standard waveforms are stored in the circuit constant value memory 18. These circuit constant values were determined through experiments, and by setting the circuit constants of the balanced circuit N in this manner, the signal from the transmitting line does not echo on the receiving line. The verification selection section 14 is the measuring section 12
The response waveform measured in step 1 is compared with each standard waveform stored in the standard waveform memory 16, and the closest standard waveform is selected. The setting section 20 reads out the corresponding circuit constant value from the circuit constant value memory 18 based on the selection result and outputs it to the setting output terminal.

Next, the operation will be explained. First, the adjustment circuit 10 is activated by a activation signal from the activation input terminal. This activation signal may occur when the called party picks up the handset. Alternatively, it may be possible to detect whether a call is being made and to automatically generate an activation signal when there is no call. Alternatively, it may be possible to detect whether or not a sound is occurring and generate a start signal when the sound occurs. Furthermore, an activation signal may be automatically generated when there is no call at regular intervals. Here, the term "no call" refers to a state where there is no input level for a certain period of time, and there is no input level for a certain period of time after sending out the adjustment pulse. When the activation signal is input, the measurement section 12 enters the measurement state and the pulse generation circuit 22 generates an adjustment pulse. The adjustment pulse is preferably a rectangular wave pulse as shown in FIG. 3a, but any other waveform may be used as long as it has the necessary frequency components. The switch SW is switched when the adjustment pulse is input, and the adjustment pulse is sent to the two-wire line 2W, so the response waveform of the adjustment pulse appears on the receiving line side and is transmitted from the waveform input terminal to the measuring section 12. input. The response waveform is measured by the measurement section 12, and the measurement result is input to the verification selection section. The comparison selection section 14 compares the measurement result with the standard waveform in the standard waveform memory 16, and selects the most similar standard waveform. Based on this selection result, the setting unit 20 changes the circuit constants of the balanced circuit N so that the circuit constant value memory 18 has circuit constant values corresponding to the selected standard waveform.

The comparison between the response waveform and the standard waveform in the comparison selection section 14 is based on the difference (absolute value) between a plurality of predetermined measurement points.
The judgment may be made based on the total value of . Alternatively, only specific measurement points may be compared. Furthermore, matching may be performed by pattern matching.

Furthermore, in the above embodiment, the circuit constant values corresponding to the standard waveform were determined through experiments, but the circuit configuration of the balanced circuit N was also devised so that the voltage value at a certain phase of the response waveform corresponds to the components of the balanced circuit. By doing so, adjustment becomes easier and the capacity of the circuit constant memory can be reduced.

A hybrid circuit adjustment device according to another embodiment of the present invention is shown in FIG. A pulse generating circuit 22 and a sampling section 24 are connected to the starting input terminal. The pulse generating circuit 22 generates adjustment pulses in response to a starting signal from the starting input terminal. The sampling section 24 is activated by the activation signal and outputs a sampling signal to the A/D conversion section 26 at a predetermined sampling period. The A/D converter 26 is connected to the waveform input terminal, performs analog-to-digital conversion on the voltage value of the response waveform of the adjustment pulse in synchronization with the sampling signal, and inputs the result to the waveform memory 28 . The waveform memory 28 stores the voltage value of the digitally converted response waveform. The ROM 30 uses the voltage value of the response waveform as an address, and each address stores a circuit constant value to be set for that voltage value. Therefore, when the output from the waveform memory 28 is used as an address, the circuit constant value of the balanced circuit is output as data. The setting section 20 outputs a setting signal according to this output data.

As described above, according to this embodiment, the functions of the collation selection section, standard waveform memory, and circuit constant value memory of the previous embodiments can be realized by one ROM. Furthermore, digitization makes it easier to handle data.

The above embodiment was about a hybrid circuit that connects a four-wire line and a two-wire line, but if two of these hybrid circuits are arranged symmetrically,
It is possible to adjust the impedance between two-wire lines and to amplify signals without generating noise.

Note that the balanced circuit is not limited to that of the above embodiment.
A balanced circuit of any configuration may be used as long as it can compensate for variations in circuit impedance.

〔Effect of the invention〕

As described above, according to the present invention, the balanced circuit can be adjusted as appropriate depending on the actual impedance of the circuit, so that even if the signal is amplified, no sound is generated.

[Brief explanation of drawings]

Fig. 1 is a block diagram of a hybrid circuit adjustment device according to an embodiment of the present invention, Figs. 2a and b are circuit diagrams showing a specific example of a balanced circuit of a hybrid circuit, and Figs. 3a and b are circuit diagrams of a hybrid circuit. FIG. 4 is a block diagram of a hybrid circuit adjusting device according to another embodiment of the present invention. DESCRIPTION OF SYMBOLS 10... Adjustment device, 12... Measurement part, 14... Verification selection part, 16... Standard waveform memory, 18... Circuit constant value memory, 20... Setting part, 22... Pulse generation circuit,
24...Sampling section, 26...A/D conversion section, 2
8... Waveform memory, 30... ROM.

Claims (1)

[Scope of Claims] 1. Circuit constants of a balanced circuit in a hybrid circuit that connects a four-wire line and a two-wire line, each having a transmitting line and a receiving line, are defined when a signal from the transmitting line is connected to the receiving line. In a method for adjusting a hybrid circuit to prevent echoes from occurring, an adjusting pulse is input to the transmitting line, a response waveform of the adjusting pulse appearing on the receiving line is measured, and this response waveform is transmitted to a plurality of channels. A method for adjusting a hybrid circuit, comprising comparing the standard waveform with a standard waveform, selecting the closest standard waveform, and setting the circuit constant of the balanced circuit to a circuit constant value corresponding to the selected standard waveform. 2. Adjusting the circuit constants of a balanced circuit in a hybrid circuit that connects a four-wire line and a two-wire line, each having a transmitting line and a receiving line, so that the signal from the transmitting line does not echo on the receiving line. A hybrid circuit adjustment device comprising: a pulse generating means for generating an adjustment pulse input to the transmitting line side; a measuring means for measuring a response waveform of the adjusting pulse appearing on the receiving line side; and a plurality of standards. a storage means storing waveforms and circuit constant values of a balanced circuit predetermined corresponding to these standard waveforms; and comparing the response waveform measured by the measuring means with a plurality of standard waveforms stored in the storage means. death,
A hybrid device comprising: a comparison selection means for selecting the closest standard waveform; and a setting means for setting the circuit constant of the balanced circuit to the circuit constant value corresponding to the standard waveform selected by the comparison selection means. Circuit regulator.