SU1506559A1 - Device for automatic monitoring of residual attenuation of unserviced audio frequency channels - Google Patents

Abstract

The invention relates to telecommunications. The purpose of the invention is to improve the measurement accuracy and reduce the recovery time of the nominal attenuation value. The device contains at the main station 1: the generator 2 of the control frequency, keys 3 and 4, the detector 5, the measuring unit 6, the control unit 7 and the recording unit 8, at the unattended station 9: the detector 10, the keys 11.18 and 19, the sampling units 12 and storage 13, comparators 14 and 15, modulo two adder 16, reference voltage source 17, feedback unit 20 and amplifier 21, as well as forward and reverse channels of link 22. In the device, if the recording length is less than the established recording length, then the attenuation of link 22 in the direction of "main station 1 - unattended station 9" is more than the norm. In this case, the damping control vector is negative, and it is necessary to reduce the attenuation by increasing the gain. If the recording length is greater than the maximum, the attenuation control vector is positive, and the attenuation needs to be increased by reducing the gain. 1 il.

Description

ate

about

Od

listened to

The invention relates to telecommunications engineering and can be used to control the seal of communication lines.

The purpose of the invention is to improve the measurement accuracy and reduce the recovery time of the nominal attenuation value.

The drawing shows a structural electrical circuit of the device.

The device contains at the main station 1 the generator 2 of the control frequency, the first key 3, the second key 4, the detector 5, the measuring unit 6, the control unit 7, the recording unit 8, the unattended station 9 detector 10, the key 11, the sampling units 12 and 13 and storage, comparators 1A and 15, summator 16 modulo two, voltage source 17, switches 18 and 19, feedback unit 20, amplifier 21, in addition, the drawing shows the forward channel and the return channel of communication link 22 .

The device works as follows.

In the initial state, when generator 2 is disconnected from the input of link 22, the voltage at the detector output is zero. From the output of the adder 16, a logical zero enters the input of the key 18, which is open, the key 19 opens the output of the feedback unit 20 and the input of the amplifier 21. Due to the lack of positive feedback in the amplifier 21 towards the main station 1, the response signal does not transmits.

When, under control of block 7, key 3 is opened, the measuring I signal from the output of generator 2 is fed to the input of link 22. At the output of the detector 10, a rectified voltage appears, proportional to the attenuation value, which enters the input of the key 11. At the output of the adder 16, square pulses appear with a logic level duration proportional to the voltage at the output of the detector 10. Pulses the logical unit receives the ha input of the key 18 and closes it, the key 19 closes the output of the block 20 and the impulses arrive at the input of the amplifier 21. In connection with the presence of positive feedback in the amplifier 21, a response signal is emitted in the direction of the main 1. This signal Antium through Clue

0

five

five

.. 4 is fed to the input of the detector 5. From the output of the detector 5, the rectified response signal is measured by measuring unit 6. Block 7 reads the voltage code from the output of measuring unit 6 at known intervals and writes the measurement result to recording unit 8. The number of records in block 8 records and determines the magnitude of the duration of the response signal, which corresponds to the magnitude of the voltage rectified from the output of detector 10. The number of records in block 8 is compared visually with the reference record length. If the recording length is greater than the minimum specified recording length, but less than the maximum specified recording length, but less than 0 than the maximum specified recording length, the attenuation is not performed, i.e. the attenuation vector is zero. If the recording length is less than the established recording length, then we can say that the attenuation of the communication line in the direction of the main station is unattended more than the Norm and the attenuation control vector in this case is negative and it is necessary to reduce the attenuation by increasing the gain. If the record length is greater than the maximum, then we can say that the damping control vector is positive, i.e. it is necessary to increase the attenuation by decreasing the gain.

A rectangular impulse of duration proportional to the value of the delay is generated only at the time of the increment of the transmission of the measuring signal and is performed by unlocking the key 3 by the block 7. Simultaneously after the unlocking of the key 3, the block 7 turns on the key 4.

Further, the device operates analogously described.

In the initial state, before transmitting and detecting the received measurement signal, the magnitudes of the voltages on the outputs of the storage sampling unit 12 and the storage sampling unit 13 are zero. The comparator 14 and the comparator 15 compare this voltage with the voltage of the source 17 of the reference voltage. As a result of the comparison, the outputs of the comparators 12 and 13 contain voltages equal to a logical zero. As a result of the logical operation Unequal5

0

five

In the adder 16, a logical zero appears at the output, which opens the key 18 and closes the key 19. In the process of transmitting the measuring signal, the rectified voltage of the received measuring signal arrives at the outputs of block 12 and block 13 and is stored in them. After a period of time sufficient to store the rectified voltage in blocks 12 and 13, unit 7 turns off key 3 and turns on key 4. In this case, the transmission of the measuring signal to the unattended station 9 stops and the input of the detector 5 is connected to the line. The magnitude of the voltage at the output of the detector 10, having taken a value of zero, and the magnitudes of the voltages in blocks 12 and 13 begin to change exponentially. The storage time in block 12 is much longer than the storage time in block 13 and is determined by the expression

t.

t

In (--Ig)

(one)

Where

e.

- constant time of voltage variation in block 12; t, is the time during which the voltage in block 13 varies to the value of the voltage of the reference voltage source; O is the permissible error of voltage variation in block 12. After the voltage at the output of block 13 becomes less than the magnitude of the voltage of the source 17 of the reference voltage, the comparator 15 switches. As a consequence, at one of the inputs of the adder 16 there is a logical zero, and at the other input from the output of the comparator 14 - a logical unit. At the output of the adder 16, a logical unit appears that turns on the key 11 to protect the blocks 12 and 13 from interfering with the response signal when monitoring communication lines with a two-wire termination and includes a set of keys 18 and 19, block 20, amplifier 21. Time interval during which a logical unit is present at the output of the adder 16, is determined by the time of discharge of the capacitor in block 12 of the value of 065596

the amount of the rectified measured signal to the magnitude of the voltage of the source 17 of the reference voltage. After the capacitor is discharged in block 12, a logical zero appears at the output of the adder 16, which turns off the set of keys 18 and 19, block 20 and amplifier 21 and closes 10 key 11. The circuit returns to its original state.

Claims (1)

Invention Formula five 0 five 0 five 0 five 0 five A device for automatically monitoring the residual attenuation of unattended tone frequency channels, which at the main station contain serially connected control frequency generator and the first key, the output of which is the forward channel input, the second key sequentially connected, the detector, the measuring unit and the control unit and the recording unit, the first input second key ow -. the input signal from the reverse channel; at an unattended station, a detector whose input is the output of the forward channel signal, the first key connected in series, the second key and the feedback unit whose output is combined with the output of the amplifier whose input is connected to the second output The second key is the input of the return channel, characterized in that, in order to increase the measurement accuracy and reduce the recovery time of the nominal attenuation value, at the main station the output of the control unit is connected to the second input The first and second keys, and a third key, the input of which is connected to t by the detector output, two sampling and storage units, the inputs of which are connected to the output of the third key, two comparators, the first inputs of which are connected to the outputs of the corresponding sampling and storage units, are entered at an unattended station, modulo two, the inputs of which are connected to the outputs of the respective comparators, and the output is connected to the second input of the third key and to the input of the first key, the source of the reference voltage, the output of which is connected to the second input m comparators.