SU915247A1 - Device for measuring instability of communication channel phase characteristics - Google Patents

Description

The invention relates to the field of communication, in particular to measurements of the phase characteristics of communication channels.

A device is known for measuring the instability of the phase characteristics of a communication channel, which contains a test signal generator at the reception, and at the reception — successively connected phase detector and low-pass filter [1].

However, the known device has a low measurement accuracy, especially at high frequencies, since the intrinsic phase fluctuations of the reference signal generator are completely included in the measurement results, and the presence of a highly stable controlled reference signal generator complicates the meter.

The purpose of the invention is to increase the measurement accuracy.

This goal is achieved by the fact that a device for measuring the instability of the phase characteristics of the communication channel, containing a test signal generator at the transmission, and a serially connected phase detector and a low-pass filter at the reception, has introduced a delay unit at the reception and subsequently

single phase shifter, phase meter and calculating and display unit, when ι this is the second phase meter input and output

5 of the low pass filter are connected respectively to the first and second inputs of the phase shifter, the output of which is connected to the first input of the phase detector and to the input of the delay unit whose output is connected to the second input of the phase detector.

The drawing shows a structural electrical circuit of the device for measuring the instability of the phase characteristics of the communication channel.

The device contains a test signal generator 1) the output of which is connected to a connector for connecting the input of the channel under study 2

“Connections, phase shifter 3, block 4 in-. holders, phase detector 5, filter 6 / low pass, phase meter 7, block 8 calculations and indications.

The device works as follows.

The phase of the test signal of the generator 1, passing through the studied communication channel 2, under the influence of destabilizing factors, receives

30 random increments that carry.

3

915247

four

information about the phase instability of the channel 2.

Measurement of phase characteristics is carried out by tracking the phase of the signal at the output of channel 2 of communication. The tracking is carried out with the help of a phase meter 7 with the test signal being fed to one of the inputs, and a signal with a reference phase to the other.

The formation of a signal with a reference 10 phase is carried out by suppressing the phase fluctuations of the signal under investigation as follows. The signal under study through the phase shifter 3 is fed to one of the inputs of the phase, 5 tsetektora 5 directly, and the other through the block 4 delay (for example, the delay line), where it is delayed by time ΊΑ (2h (where ϊ is the nominal frequency of the signal under study 20, ΐ = 0,1,2, ...). The output signal of the phase detector .5 containing information about the phase difference of the source and delayed signals under study, and the output of the filter 25 of the lower 25 frequencies receive an error signal proportional to the phase difference of these signals. In the absence of phase fluctuations in the communication line with drove the error at the output of the low pass filter 6 is zero and the phase shifter 3 introduces a constant phase shift. Otherwise, phase shifter 3 fulfills the phase fluctuations of the signal, whereby

the output signal of the phase meter 7 is OPPORTANT to the fluctuations under study and block 8 determines the required characteristics of the phase fluctuations, for example

their rms. value at the ends of the time interval.

Due to the introduction of block 4 delay, phase shifter 3, phase meter 7 and block 8 of calculations and indications, the proposed meter does not contain a reference signal generator, its own phase fluctuations of which distort the measurement results, which increases the measurement accuracy.

Claims (1)

Claim A device for measuring the instability of the phase characteristics of a communication channel, containing a test signal generator at the reception, and at the reception a series-connected phase detector and a low-pass filter, characterized in that, in order to improve measurement accuracy, a delay block and a series-connected phase shifter are introduced at the reception , a phase meter and a calculation and indication unit, while the second input of the phase meter and the output of the low-pass filter are connected respectively to the first and second inputs of the phase shifter, the output of which is dinei to a first input of the phase detector and to the input of delay unit, whose output is connected to the second input of the phase detector.