JPS60130253A - Metering pulse transmission system - Google Patents

Abstract

PURPOSE:To decrease the deterioration of characteristic of a metering pulse by turning on/off talking current with logical switch control to decrease application time of specific noise generated attended with a minute current of a non-feeding talking current supply circuit. CONSTITUTION:The normal feeding and the reverse feeding are changed over by applying a control voltage to terminals N, R in a metering pulse transmission circuit comprising a normal feeding current supply circuit Bn giving a battery level to a subscriber line A and ground level to a subscriber line B, a reverse feeding current circuit Br supplying a current of opposite polarity, a normal filter circuit Cdcn, a reverse filter circuit Cdcr and a logical circuit Nrc, the time when both the current supply circuits are activated is decreased by signals Bfn, Bfr and the deterioration of characteristic due to application of specific noise generated together with a minute current of non-supply side onto the feeding side is reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION (Technical Field) The present invention relates to a billing/gurus transmission system for a local exchange accommodating public telephones.

(Prior Art) Conventionally, a billing/gurus sending circuit has had a circuit configuration as shown in FIG. In the figure, Bn is a normal power feeding communication current supply circuit that sends a battery to subscriber line A and earth air to subscriber line B, and Br is a reverse power feeding circuit that sends a battery to subscriber line B and earth air to subscriber line A. Call current supply circuit, Bf
n and Bfr are control signals for turning on and off the communication current of each communication current supply circuit at the output stage. Also, if Cdcn,
A normal filter circuit that gradually decreases and gradually increases the amount of communication current by controlling the current drawn from the feed current of the normal power supply communication current supply circuit, and is controlled by the signal N.Furthermore, Cdcr is a reverse filter circuit, and the signal It is controlled by R.

The operation of such a charging pulse sending circuit is as follows. By keeping the control signals Bfn' and Bfr constantly on, turning on the signal N, and turning off the signal R' (z, C
dcn enters the operating state and performs normal power supply, and by turning on the signal R and turning off the signal N, the reverse filter circuit Cdcr enters the operating state and performs the reverse power supply. For polarity reversal, turn on signals N and R.

This is done by turning it off, but in the transition period,
Rather than making a sudden change, the filter characteristics of the normal reverse filter circuit Cdcn + Cdcr gradually reduce the amount of current drawn from the feedback current of the communication current supply circuit and gradually increase it from a minute current state. I will do it.

Since this kind of billing/gurus sending circuit controls the current amount of the call current supply circuit in an analog manner, the non-powered call current supply circuit is not turned off at the output stage and remains active and generates a minute current. In addition, there was a drawback that inherent noise generated from the circuit was added to the power supply communication current supply circuit, deteriorating the characteristics.

(Object of the Invention) It is an object of the present invention to alleviate these drawbacks, and to control the output stage of the other communication current supply circuit to be turned off while one communication current supply circuit is supplying power. This provides a billing/gurus sending system that prevents the addition of inherent noise that occurs along with the minute current in the non-power-supplied telephone current supply circuit.

(Structure of the Invention) The present invention has a switch control function that turns on and off the call current by logical control and a current control function that changes the amount of call current in an analog manner in supplying call current to terminals of a telephone exchange. It is characterized by using two communication current supply circuits, connecting the outputs of each communication current supply circuit consisting of two wires in reverse to each other, and transmitting billing/gurus by selectively performing switch control and current control. This is a billing pulse sending method.

(Example) A detailed explanation will be given according to an example.

FIG. 2 shows the configuration of one embodiment of the present invention. Call current supply circuit Bn x B r s Filter circuit Cdcn
, Cdcr, signal Bfn 1 Bfr + N +
R% subscriber lines A and B are the same as in FIG. t
Further, Nrc is a logic circuit that outputs the enable signal N as the signal Bfr and the enable signal R as the signal Bfn.

Next, the billing/gurus sending circuit configured in this way is connected to the third
This will be explained using figures. In FIG. 3, the signal N r R
+Bfn+Bfr is a control signal equivalent to that in FIG. 2, and a and b are speech current waveforms. In the speech current waveform a in Figure 3, normal power supply is performed when signal N is on and signal R is off, and short/grace power supply is performed when signal R is on and signal N is off. Huru. Furthermore, during the period from time t1 to t2 when the polarity is changed from normal power supply to reverse power supply, both signals Bfn and Bfr are turned on by the logic circuit Nrc, and both communication current supply circuits are in the active state, but the signal R is turned off. Therefore, the communication current supply circuit on the lever side is in a non-power-supply state. At time t1, the signal N changes from on to off, so that the normal filter circuit Cdcn
The current drawn from the feedback current of the reverse current supply circuit is gradually increased according to the filter characteristics of the normal power supply side, and the current on the normal power supply side gradually decreases to zero, and then at time t2, the signal R on the reverse side changes from OFF to ON. As a result, due to the filter characteristics of the reverse filter circuit Cdcr, the current f extracted from the feedback current of the reverse current supply circuit gradually decreases, and the reverse current on the reverse power supply side gradually increases, completing the polarity reversal. During this polarity inversion time t2, the normal side communication current supply circuit Bn is turned off at the same time as the signal R is changed from off to on, and the signal Bfn is turned off. In this way, the time that both talk current supply circuits are in the active state is shortened, and the addition of inherent noise in the talk current supply circuits is prevented.

Also, during the polarity reversal time t4 to t6 from reverse power supply to normal power supply, although the normal and reverse power supply circuits are reversed, the communication current on the reverse power supply side is changed in the order described above for time t.
4, and the communication current on the normal power supply side continues for a time t.
This is done by increasing gradually in 5 steps. And lever feed Φ
1j The talking current supply circuit turns off the signal Bfr at the same time as the signal N of the normal power feeding side talking current circuit changes from OFF to ON at time t5, and is in the disconnected state. Shorten the length to reduce the addition of inherent noise.

Therefore, in the speech current waveform a in FIG. 3, the time during which two speech current feeding circuits are operating simultaneously is only α. Therefore, when the two communication current supply circuits are constantly operating, it is possible to prevent characteristic deterioration due to the inherent noise generated in the small current of the non-power supply side communication current supply circuit being added to the power supply side communication current supply circuit. It is possible to realize reduced charges and virus transmission.

In addition, in the current control by the filter circuit Cdcn + Cdcr shown in Fig. 2, due to variations in the characteristics of the filter circuit, that is, the characteristics of the current drawn from the feedback current of the communication current supply circuits Bn and Br, the communication current at the time of polarity reversal is does not necessarily approach zero. If the current drawn from the feed/punch current is large, the feed current is quantitative, so as the drawn current gradually increases, the talking current follows and gradually decreases, but when it reaches zero, it cannot follow it any further, and the fourth As shown by the solid line in the speech current waveform (2) in the figure, compared to the speech current waveform (1) where the speech current asymptotically approaches zero, sharp points Pa and Pb of the differential coefficient are created, and frequency components within the voice band are generated. However, it has the disadvantage of causing noise degradation. (In FIG. 4, the broken line indicates the characteristics of the current drawn.) The first method for reducing the noise deterioration described above will be explained. By increasing the time constant of the fill circuit that gradually reduces the communication current, the communication current waveform shown in FIG. 4 (3) can be obtained. This communication current gradually decreases at times t2 to t4, and then in the active state of the low current state, the communication current on the polarity reversal side is gradually increased to perform polarity reversal.

The second method uses the control signals N, R, Bfn, Bf
The communication current supply circuit Bn is controlled by controlling r as shown in Fig. 5 (1).
, Br are switched at the same time, and the characteristics of the filter circuit are set so that the talking current gradually decreases and the trailing current becomes a state. By controlling in this way, the communication current waveform shown in FIG. 5(2) can be obtained. This communication current gradually decreases from time t, i or t3 and reaches Bn+Br at time t21 t, , in a constant current active state.
At the same time, the switching current on the polarity reversal side is gradually increased to perform polarity reversal. By performing the method in Section 1.2, it is possible to
), the points Pa and Pb where noise occurs due to characteristic variations are shown in Figure 4 (3) and 5.
This does not occur in Figure (2), and it is possible to transmit billing and noise with less noise characteristic deterioration.

(Effects of the Invention) As explained in detail above, according to the present invention, when both communication current supply circuits are activated, the addition time of the minute current and the inherent noise generated from the circuit is shortened, thereby reducing characteristic deterioration. It is possible to perform billing and virus transmission.

It is possible to perform billing and signal transmission with less deterioration of noise characteristics due to filter characteristics, characteristics, and fluctuations of the filter circuit.

[Brief explanation of drawings]

FIG. 1 is a conventional billing pulse sending circuit, FIG. 2 is a circuit diagram explaining an embodiment of the present invention, FIG. 3 is a time chart explaining the operation of FIG. 2, and FIGS. 4 and 5 are FIG. 7 is a waveform diagram illustrating a second example. Bn...Normal power supply call current supply circuit, Br...Sex power supply call current supply circuit, Cdcn...Normal feed/l/event circuit, Cdcr...Reverse filter circuit, Nrc...Logic circuit. Figure 4

Claims (2)

[Claims] (1) In supplying speech current to the terminal of a telephone exchange, a speech current having a switch control function to logically turn off the speech current according to FL+IJ control, and a current control function to change the speech current amount in an analog manner. Using two supply circuits,
A billing/gurus sending system characterized in that the outputs of each call current supply circuit consisting of two wires are reversely connected to each other, and the yen money/gurus are sent out by selectively performing switch control and current control. (2) In the current control layer, the communication current being supplied from the output of the first communication current supply circuit is gradually reduced to a low current or constant current active state, and the communication current of the second communication current supply circuit is gradually increased. , the billing/gurus sending system according to claim 1, characterized in that the polarity is reversed.