RU1775864C - Noise level meter in a communication channel - Google Patents

Abstract

Usage: electric communication. SUMMARY OF THE INVENTION: 1 communication channel (1), 1 block

Description

1720 27

phage 1

The invention relates to telecommunications and can be used in measuring parameters of links, paths, communication channels and broadcasting.

The purpose of the invention is to expand the range of measured interference levels and increase the accuracy of measurements.

In FIG. 1 shows a structural electrical diagram of the proposed device; in FIG. 2 - time diagrams explaining his work,

A device for measuring the level of interference in a communication channel contains a delay unit 2, an adder 3, a linear detector 4, a Schmitt trigger 5, a key 6 and a pilot signal generator 7 on the transmitting side of the test channel 1, and a narrow-band filter 8 on the receiving side , linear detector 9, first and second Schmitt triggers 10, 11, element 12, first key 13, blocking filter 14, quadratic detector 15, interference integrator 16, amplifier 17, synchronizer 18, reference integrator 19, square root extracting unit 20, second and third keys 21, 22, jammer 23, t rigger 24, fourth key 25, generator 26, third Schmitt trigger 27 and signaling unit 28,

The device operates as follows. .

The information signal from the input of the device goes to the input of the adder 3 and to the input of the delay unit 2. The output of adder 3 is connected to the input of communication channel 1. The signal 8 of block 2 is delayed by an amount corresponding to the group propagation time of the signal on the communication channel 1. Therefore, the information signals at the output of the communication channel 31 and at the output of the delay unit 2 appear at the same time points.

The signal from the output of the delay unit 2 is fed to the input of the linear detector 4, which selects the enveloping information signals. These envelopes go to the input of Schmitt's trigger 5. In the absence of an information signal о from the inverting output of the Schmitt trigger 5, the resolving potential arrives at the input of the key 6. A pilot signal generator 7 is connected to the second input of the key 6, and the signal of the generator 7 in the absence of an information signal is fed to the input of the communication channel 1 through an adder 3, in which the information signals and the pilot signal are added.

On the receiving side of the communication channel 1, the signals of the generator 7 are extracted using a narrow-band filter 8 and fed to a linear detector 9. which

extracts the envelope of the signals of the generator 7 at the output of the communication channel 1. From the output of the linear detector 9, the signal is fed to the input of the first Schmitt trigger 10 and simultaneously to the input of the second Schmitt trigger 11. The trigger threshold of the first Schmitt trigger 10 is selected to be lower than the minimum level of the information signal, and the trigger threshold of the second Schmitt trigger 11

0 is set equal to the minimum acceptable level of information signals. The non-inverting output of the first Schmitt trigger .10 and the inverting output of the second Schmitt trigger 11 are connected to the inputs

5 elements And 12.

When the envelope of the information signal arrives from the output of the linear detector 9, the first and second Schmitt triggers 10, 11 are triggered. In this case, the input of element And 12 from the non-inverting output of the first Schmitt trigger 10 receives a logical 1 signal, and from the inverting output of the second Schmitt trigger 11, a logical 0 signal.

5 In this case, at the output of the element And 12, a logical 0 signal is generated, which goes to the control input of the first key 13 and keeps it closed. At this time, if there is an information signal of the communication channel 1 under study, this signal is transmitted through the closed first key 13 not connected to the blocking filter 14 and no interference measurement is performed at this time,

5 When a pause occurs, i.e. in the absence of an information signal, the resolving potential comes from the inverting output of the Schmitt trigger 5 to the input of the key 6. A generator 7 is connected to the second input of the key 6, the signal of which, if there are pauses in the information signal, enters the input of the communication channel 1 through the adder 3, is extracted by a narrow-band filter 8, and is detected by a linear detector

5 9 and starts the first Schmitt trigger 10, which leads to the appearance of a logical unit signal at its non-inverting output, which is fed to the input of the And 12 element. At the second input of the And 12 element, the signal of the logical unit coming from the inverting output of the second Schmitt trigger 11 .

Thus, in the presence of pauses in the information signal to the inputs of the element

5 and 12, two signals of a logical unit arrive, the first key 13 opens and the voltage of the noise existing during a pause in the information signal (Fig. 26) is supplied through the blocking filter 14 to the input of the quadratic detector 15.

The blocking filter 14 impedes the passage of the pilot signal. The narrow interference band cut out by this filter does not introduce a significant error into the results of interference measurements and can be taken into account, if necessary, by making a constant small correction to the measurement results.

From the output of the quadratic detector 15, the signal is supplied to the integrator 16 interference. The voltage at the output of the quadratic detector 15 is proportional to the square of the input voltage. The need for a quadratic detector is associated with the fact that it is subsequently required to integrate power interference. This will determine the average interference power for the selected time interval.

The synchronizer 18 generates pulses (Fig. 2a), which follow at time intervals T, during which the interference power is averaged. As a synchronizer, you can choose a multivibrator.

In FIG. 26 it is seen that in the time interval T1 at the output of the first key 13, the interference was twice, in the time interval TK - once. In the time interval T2 there were no pauses of information signals and there was no voltage, no interference in this time interval to the output of the first key 13.

The information of the interference integrator 16 is read and reset when the leading edge of the synchronizer pulse 18 arrives. The start of the integration time corresponds to the arrival of the leading edge of the synchronizer pulse 18.

From the output of the integrator 16 (Fig. 2c), the signal is fed to the input of the amplifier 17 with gain control. In order for the signal at the output of amplifier 17 to depend only on the amount of interference in the communication channel and to vary little from changing the duration of the signals at the output of the first switch 13, voltage is supplied to the second input of amplifier 17 from the reference integrator 19.

The output voltage of the reference integrator 19 (Fig. 2d) linearly decreases the transmission coefficient of the amplifier 17 (Fig. 2e) as the signal duration at the output of the first switch 13 increases. The integrator circuits 16, 19 must be identical.

Since a constant voltage is supplied to the input of the reference integrator 19 from the And 12 element in the presence of pauses, the output of the amplifier 17 receives a signal whose value is proportional to the interference power in the communication channel, and the value of this signal does not depend on the change in the duration of the pauses in the channel communication.

A square root extractor 20 is connected to the output of the amplifier 17, the output of which is numerically equal to the rms value of the interference voltage of the communication channel 1.

From the square root extraction unit 20, a signal is supplied through the second and third keys 21, 22 to the jammer 23.

When in the averaging interval T was not

0 pauses, then the resolving potential from the trigger 24 will not come to the input of the second key 21 and there will be no interference signals at the output of the second key 21.

Trigger 24 is reset

5, the state is at the trailing edge of the synchronizer pulse 18. When a signal is received from the And 12 element, an enable potential is applied to the input of the trigger 24 to the input of the second key 21 (Fig. 2f), and the interference signal of the communication channel 3 will be transmitted to the output of the second electronic key 21 .

If in the averaging interval from the And element 12 there is no signal at the input of the trigger 24, then from the inverting output of the trigger 24

5, the enabling potential arrives at the fourth electronic key 25. The second input of the fourth key 25 receives a signal from the generator 26, which, through the fourth and third keys 25, 22, enters the jammer 23. The presence of the signal of the generator 26 at the input of the recorder 23 indicates that the measurement of interference in the time interval T was not performed.

resolving potential to the third

5, the key 22 is supplied at the moment of the leading edge of the pulse from the synchronizer 18, and the voltage from the third key 22 (Fig. 2g), which corresponds to the value of the mean square value of the interference voltage in the communication channel, is supplied to the input of the recorder 23 that no interference measurement is performed at a given time interval. Upon arrival of the leading edge of the synchronizer pulse 18, the amount of interference is recorded by the recorder 23, the integrators 16, 19 are reset, and the trigger 24 is returned to its original state. If necessary, the pulses of the synchronizer 18 can be used to

0 to zero the recorder 23 or to pull the tape.

Using the invention, it is possible to continuously monitor the amount of interference during operation of all

5 communication channels. For example, it is possible to continuously monitor the amount of interference in the paths of radio houses, in transmitters, sound and amplification systems, professional tape recorders and in all other cases.

When organizing continuous monitoring of the amount of interference, it is advisable to connect the third Schmitt trigger 27 to the output of the amplifier 17 or to the square root block 20, which will turn on the alarm in cases when the amount of interference exceeds a predetermined threshold. In this device, a third Schmitt trigger 27 is connected to the output of the square root extractor 20. If the permissible interference in the communication channel 1 is exceeded, the signal from the third Schmitt trigger 27 is fed to the signaling unit 28, which includes an alarm that the noise p is above normal and, if possible, switches the working communication channel to the backup one.

If, for some technical implementation of the device, it is necessary to control the amount of interference of a not very long communication channel (radio house path, powerful transmitter, sound and amplification system), then the signal from the inverting output of Schmitt trigger 5 can be directly connected to the first key 13, the reference integrator 19 and trigger 24. The technical implementation of the device is greatly simplified.

When it becomes necessary to measure and control the psophometric noise of the communication channel, a psophometric filter is connected between the first electronic key 13 and the quadratic detector 15.

Claims (1)

The claims A device for measuring the level of interference in a communication channel, comprising an adder on the transmitting side, the output of which is connected to the input of the communication channel, and a pilot signal generator, and on the receiving side, an alarm unit, characterized in that, in order to expand the range measured noise levels and porchitschitsy / accuracy of measurements, series-connected delay block, linear, trigger are entered on the foregoing side Schmitt and the key, the second input and the output of the one are connected respectively to the output re of the pilot signal and the first result of the adder, the second input of which is connected to the input of the delay unit, which is the output of the device for measuring the level of interference in the communication channel, and the receiving side is the reference integrator, the first Schmitt trigger, a series-connected narrow-band filter, a linear detector, the second Schmitt trigger, element I. the first key, a filtered filter, a quadratic detector, an interference integrator, an amplifier, a square extraction unit root and third Schmitt trigger, sequentially connected synchronizer, trigger, second key, third key and jammer, and a series-connected generator and fourth key, the input of a narrow-band filter connected to the output of the channel connection with the second input of the first key, the output of the linear detector through the first Schmitt trigger is connected to the second output of the element And, the output of which is connected to the first input of the reference integrator and to the trigger installation input, whose inverse output is connected to the second input of the fourth key; the output of which is connected to the first input of the third key, the second input of which is connected to the control inputs of the jammer, reference integrator, and integrator of the synchronizer, the input and output of the third Schmitt trigger are connected respectively to the second input of the second key and to the input of the signaling unit, and the output of the reference integrator is connected to the second input of the amplifier. $ Oh Fig 2