RU1775863C - Method of noise level measurement in a communication channel - Google Patents

Abstract

Usage: electric communication. The essence of the invention: on the transmitting side of the communication channel, pauses in the transmission of information signals are allocated and at this time a pilot signal is transmitted in the band of the communication channel with a level lower than the interference level, a pilot signal is isolated on the receiving side and only during its time actions measure the interference of a communication channel. 2 ill.

Description

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 the expansion of the range of measured values of interference and improving the accuracy of measurements

In FIG. 1 shows a structural electrical diagram of a device that implements the proposed method; in FIG. 2 are timing diagrams illustrating its operation.

The device for implementing the proposed method contains on the transmitting side of the test communication channel 1 a first linear detector 2, a first Schmitt trigger 3, a first key 4 and a pilot signal generator 5, and on the receiving side a narrow-band filter 6, a second linear detector 7, and a second trigger 8 Schmitt, second key 9 quadratic detector 10, interference integrator 11, amplifier 12, synchronizer 13, reference integrator 14, square root extractor 15 third and fourth keys 16, 17, jammer 18, trigger 19, fifth key 20, generator 21, third trigger Schmitt 22 and alarm unit 23.

The essence of the proposed method lies in the fact that such intervals are allocated on the transmitting side of the communication channel

time during which there are no information signals, at which time a pilot signal is transmitted in the band of the communication channel with a level lower than the interference level; the pilot signal is isolated at the receiving side and only during the time of its operation the interference of the communication channel is measured.

A device that implements the proposed method works as follows.

Information signals are fed simultaneously to the input of the test communication channel 1 and to the input of the first linear detector 2, which extracts the envelopes of the information signals.

These envelopes are served on. input of the first Schmitt trigger 3. In the absence of an information signal from the inverting output of the first Schmitt trigger 3, an enable potential is supplied to the input of the first key 4, and a pilot signal generator 5 is connected to the second input of the first key 4, which, in the absence of an information signal, goes to the input of the communication channel 1. The signal level of generator 5 is chosen below the permissible interference level, and therefore, the presence of a pilot signal does not affect the quality of transmission of information signals.

Thus, the first linear detector 2, the first trigger 3 Schmittzgen VJ VI

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torus 5 and first key A highlight the pauses that exist when transmitting an information signal at the transmitting end and at this time transmit a pilot signal in the channel frequency band with a level lower than the permissible interference level

At the receiving end of the communication channel 1, the signals of the generator 5 are extracted using a narrow-band filter 6 tuned to the frequency of the pilot signal and transmitted to a second linear detector 7, which extracts the envelope of the signals of the generator 5 at the output of the communication channel 1. From the output of the second linear detector 7, the signal is fed to the input of the second Schmitt trigger 8. The threshold of operation of the second Schmitt trigger 8 is set below the level and the pilot signal. The non-inverting output of the second Schmitt trigger 8 is connected to the control input of the second key 9, the output of which is connected to the input of the quadrator 10,

In the absence of a harmonic-shaped pilot signal, the voltage at the input of the second Schmitt trigger 8, coming from the output of the narrow-band filter 6 through the second line detector 7, is below the trigger threshold of the trigger 8, and there is a logic zero signal at its non-inverting output. This signal is supplied to the control input of the second key 9 and keeps it closed (Fig. 26). Therefore, in the absence of a pilot signal at the receiving end of the communication channel 1, the second key 9 is closed and the signal from the output of the communication channel 1 does not arrive at the input of the quadratic detector 10. The appearance of a harmonic-shaped pilot signal at the output of the communication channel 1 leads to the appearance of noise voltage at the input of quadratic detector 10 (Fig. 26).

The output voltage of the quadratic detector 10 is proportional to the square of the input voltage. The need to use a quadratic detector is associated with the fact that it is subsequently required to integrate power interference, which will allow determining the average interference power over a selected time interval.

The synchronizer 13 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 shows that in the time interval T1 at the output of the second key 9, the interference was twice, in the time interval TK once. In the time interval T2 there were no pauses of information signals and the interference voltage in this time interval was not received at the output of the second switch 9

Reading and resetting the information of the interference integrator 11 is performed at the moment of the arrival of the leading edge of the synchronizer pulse 13 The start of the integration time corresponds to the arrival of the leading edge of the synchronizer pulse 13

From the output of the integrator 11, the signal is input to the amplifier 10 by gain control. In order for the signal at the output of amplifier 12 l to depend only on the amount of interference in the communication channel 1 and vary little from the change in the duration of the signals at the output of the second switch 9, the voltage of the atop resistor integrator 14 is supplied to the second input of the amplifier 12.

The output voltage of the reference integrator 14 (Fig. 2d) linearly reduces the gain of the amplifier 12 (Fig. 2e) as the signal duration increases by

0 the output of the second key 9. The circuit integrators 11 and 14 should be identical.

Since the input of the reference integrator 14 from the inverting output of the second Schmitt trigger 8, in the presence of pauses, receives a constant voltage, the signal at the amplifier output is proportional to the interference power in the communication channel, and the value of this signal does not depend on the change

0 duration of pauses in the communication channel.

An amplifier is connected to the output of amplifier 12

15 of extracting the square root, the output signal of which is numerically equal to the rms value of the voltage across the 5 channel 1 coupling.

From the block 15 extraction of the square root signal through the third and fourth keys

16 and 17 goes to the jammer 18.

When in the averaging interval T was not

0 pauses, to the input of the third key 16 will not receive the resolving potential from the trigger 19, and interference signals at the output of the third key 16 will be absent

Trigger 19 is reset

5 is the state of the trailing edge of the synchronizer pulse 13. When a logical 1 signal is received from the second Schmitt trigger 8, an enable potential is applied to the input of the third key 16 to the input of the third key 16 (fi. 2e),

0 and the output of the third key 16 receives the interference voltage of the communication channel 1

If, in the averaging interval from the second Schmitt trigger 8, the logical 1 signal does not arrive at the input of trigger 19, then from the inverting output of trigger 19, the resolving potential to the fourth key 17 comes to the second input of the fourth key

17 receives a signal from the generator, which through the fifth and fourth keys 20, 17 will go to the recorder 18 pomelo

the signal of the second generator 21 at the input of the recorder 18 indicates that the measurement of interference in the interval T was not performed.

The resolving potential for the fourth switch 17 is applied at the moment of the leading edge of the pulse from the synchronizer 13, and the voltage from the fourth switch 17 (Fig. 2g), which corresponds to the value of the mean-square interference voltage in the communication channel 1 or indicates that interference measurement is not performed in this time interval. Upon arrival of the leading edge of the pulse of the synchronizer 13, the amount of interference is recorded by the recorder 1 & the integrators 11, 14 are reset, and the trigger 19 is returned to its original state. If necessary, the pulses of the synchronizer 13 can be used to zero the recorder 18.

Using the present invention, it is possible to continuously monitor the amount of interference during the entire operation of the communication channel 1.

When organizing continuous monitoring of the amount of interference, it is advisable to connect the third Schmitt trigger 22 to the output of the amplifier 12 or to the square root block 15, which will turn on the alarm in cases when the amount of interference exceeds a predetermined threshold. In this example, the third Schmitt trigger 22 is connected to the output of the square root extractor 15. If the permissible value in the communication channel is exceeded, the signal from the third Schmitt trigger 22 is fed to the signaling unit 23, which includes an alarm that the interference exceeds normal

and, if possible, switches the working channel 1 of the communication to the backup

If during some technical implementation of the method it is necessary to control the noise of the not very long channel 1 of communication (radio path, powerful transmitter, sound and amplification system), then the signal from the inverting output of the first Schmitt trigger 3 can be directly connected to the second electronic a key 9. a reference integrator 14 and a trigger 19. 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 included between the second electronic key 9 and the quadratic detector 10.

Claims (1)

The claims A method for measuring the level of interference in a communication channel, which consists in the fact that pauses in the information signal are allocated on the transmitting side, at the beginning of each of which they begin to generate a pilot signal, which is transmitted in the frequency band of the information signal, and a pilot is allocated on the receiving side -signal and measure the amount of interference, which is compared with an acceptable threshold, characterized in that, in order to expand the range of measured interference values and increase the accuracy of measurements on the transmitting side, a pilot signal is formed with a level below d uro.en admissible interference and transmitted throughout, of the information signal, and the reception side noise value measured only at intervals of time the presence of the pilot signal. Phage i g / So f ЈZ about G2 tk