SU553752A2 - Device for automatic monitoring of the state of a communication channel by noise level and residual attenuation - Google Patents

Description

A control amplifier 6 is connected to the output frequency 1 of the control frequency; it is connected to the power distribution 9, and at the receiving side, parallel to the residual attenuation measurement channel 8, the noise level measurement channel 10 and the electronic switching circuit 11 are connected to the power distributor 9 serially connected amplifier limiter 12, driver of 13 clock pulses, frequency divider 14, waiting for multivibrator 15 and DC amplifier 16, and the channel noise level measurement 10 contains serially connected key amplifier 17, threshold noise level measurement circuit 18 and delay circuit 19; in addition, the device contains a subscriber switching control unit 20 and a shunt transistor 21, the output of the OR element 22 through the serially connected control unit 20 switching subscribers and bypass transistor 21 is connected to the output of key amplifier 6; a key amplifier 23, a cascade control circuit 24, an electronic switch, a delay circuit 25, a buffer cascade 26, and an inverter 27.

The device works as follows.

The control frequency, having a highly stable amplitude, is generated by generator 1, amplified by key amplifier 6, and sent through the filter bank 2 in the direction of transmission of a four-wire communication channel. The filter unit 2 is used to form a reference subchannel and information channel in the frequency band of a standard telephone channel of communication. The control frequency, together with the information signal, is fed to the receiving side of the four-wire communication channel and the filter unit 3, which serves to separate the information and control signals. The control frequency through the filter unit 3 and the voltage amplifier 4 is supplied to the power distributor 9, at the output of which the control frequency energy is distributed in two directions. A portion of the energy through the open key amplifier 23 is supplied to the threshold circuit 5 for measuring residual attenuation, which is triggered by the change in the residual attenuation of the communication channel in excess of long-range limits.

Another part of the energy is through limiter 12, the driver of 13 clock pulses arrives at the electronic automatic switching stage 7 with frequency divider 14. From the cascade 7, after a strictly defined time equal to the partial from the division of the control signal and the selected division factor, the impulse goes to the waiting multivibrator 15. Under the action of this pulse, the standby multivibrator 15 tilts and, through the DC amplifier 16, closes the key amplifier 6, the key amplifier 23 and opens the key amplifier

17, whereby the sending of the control frequency signal to the communication channel and the measurement of the residual attenuation value is stopped, and the threshold circuit 18 begins to measure the noise level in

control subchannel. After the standby multivibrator 15 returns to its initial position, the measurement process is repeated.

To limit the possibility of an unjustified determination of the failure of the St. 311 channel during short-term interruptions or the occurrence of short-term schum bursts, delay circuits 19 and 25 are provided that perform the functions of the communication link duration analyzer and analyzer

duration of action of schum.

Since the control frequency is not supplied to the communication channel at the moment of noise measurement, the threshold circuit 5 responds to this as if the communication channel is faulty. Therefore, a buffer cascade 26 is provided, to which, at the time of measuring the schum, a blocking potential is applied through the amplifier of a constant current 16.

The signal about the failure of the communication channel, fixed by the threshold circuit 5 for measuring the residual attenuation, through the series-connected buffer cascade 26, the inverter 27, the delay circuit 25 is fed to the input of the OR element 22.

The signal about the failure of the communication channel, fixed by the threshold noise level measuring circuit 18, through the delay circuit 19 is fed to the input of the element OR 22.

From the output of the element OR 22, a channel malfunction arrives at the subscriber switching control unit 20, which controls the operation of the shunt transistor 21 connected to the output of the key amplifier 6. In response to the incoming signal

communication channel malfunction; the subscriber switching control unit 20 outputs a pulse to the input of the shunt transistor 21, the duration of which must be no less than the measurement time of the residual attenuation plus the time

measure the level of schuma. Under the action of this pulse, the shunt transistor 21 opens and by its output shunts the output of the key amplifier 6 and thereby stops the supply of the control frequency signal to the communication channel. The absence of the control frequency signal at the opposite end of the communication channel is perceived by the threshold circuit 5 as a channel failure, and similarly to the above, a signal is sent that the subscriber is switched to the backup channel.

Claims (1)

1. USSR author's certificate No. 277021, cl. H 04B 3/04, 1969 - a prototype. ls ij j g - To the scheme to oHff / riacfM