SU429372A1 - RADIO IMPULSE PHASOMETER - Google Patents

Description

one

The invention relates to a technique of radio-electronic phase measurements and can be used in measuring phase shifts between short, including single radio pulses at high frequencies, as well as in the study of signals with a rapid change in phase shift.

Known phase meters with frequency conversion, containing the reference and measuring channels, which are made of serially connected input devices, mixers and amplifiers of intermediate frequency and connected to a phase detector loaded on a low-pass filter, as well as a local oscillator connected to both mixers.

In the study of short radio pulses, the intermediate frequency of the phase meter should be chosen sufficiently high. However, both limiters and automatic gain control (AGC), which are used in well-known phase meters to equalize the amplitudes of signals at frequencies above 0.5-1 MHz, have very large amplitude-phase errors. These errors increase with an increase in the dynamic range of the signals and significantly reduce the accuracy of phase shift measurements.

The aim of the invention is to reduce the errors in measuring the phase shift between short radio pulses in a wide dynamic range of amplitudes when it is impossible to use a low intermediate frequency.

For this, a controlled attenuator is connected between the heterodyne output and the inputs of both mixers, and the control pendants of the attenuator are composed of a series-connected resonant filter at a double intermediate frequency, an amplitude detector and a feedback amplifier, where the input of the resonant filter is connected to the output of the phase detector, and feedback - to the attenuator control input.

The drawing shows a block diagram of the proposed radio-pulse phase meter.

The phase meter contains measuring and reference channels, which are made of series-connected input devices 1 and 2, mixers 3 and 4, amplifiers 5 and 6 of intermediate frequency. The outputs of amplifiers 5 and 6 are connected to a phase detector 7, which is loaded onto a low-pass filter 8 and a resonant filter 9 at a doubled intermediate frequency. The local oscillator 10 is connected via a controlled attenuator 11 to the second inputs of mixers 3 and 4. The output of the resonant filter 9 is connected to an amplitude detector 12 connected through a feedback amplifier 13 to the control input of the attenuator 11.

Radio pulse phase meter works as follows.

High-frequency oscillations, the phase shift between which you want to measure, are nodalized to input devices 1 and 2, and then to mixers 3 and 4. At the same time, the tension of the local oscillator 10 is supplied to the mixers through attenuator 11 arriving at their inputs, with minimal errors in a large dynamic range of amplitudes.

In this case, the intermediate frequency voltage at the output of the mixer 3 is proportional to

and t - cos Ki + g + Tg) The output voltage of the mixer 4

and „A cos (u) n / + y),

where Ei and EZ are the amplitudes of the studied signals arriving at the input devices 1 and 2;

EG - the amplitude of oscillation of the local oscillator entering the mixers 3 and 4;

Fg-- the initial phase of these oscillations;

(ip - intermediate circular frequency;

Ф - measured phase shift.

The intermediate frequency signals from the outputs of mixers 3 and 4 are amplified by amplifiers 5 and 6 and fed to the inputs of phase detector 7, which, like mixers, operates in the signal multiplication mode. At the same time, the composition of its output signal includes a DC voltage and a doubled intermediate frequency.

t / Fd cos (f + E, cos (2с „g + +). The first component of this sum is the result of measuring the phase shift between the studied signals and, after separation by the low-frequency filter 8, is fed to the output of the phase meter

B "x-A cos.

The second component is filtered by the resonant filter 9 and is fed to the amplitude detector 12. The voltage at its output is proportional to the value, i.e.

coefficient of the cosine of the phase shift in the output voltage of the phase meter.

The voltage from the amplitude detector 12 is amplified by the feedback amplifier 13 and fed to the control input of the attenuator 11. Thus, the auto-regulation circuit is closed, maintaining the value of EiEzEf constant for all changes in the amplitudes of the input signals Ei and EZ by adjusting the heterodyne voltage Ef.

Since the oscillation amplitude of the local oscillator is controlled in the common channel of the phase meter, the amplitude-phase errors of the attenuator 11 do not introduce errors into the results of measuring the phase shift.

The mixers and phase detector in the proposed radio pulse phase meter can be performed on field-effect transistors in a variable resistance mode. Occurrences

multipliers of such mixers and phase detectors are much smaller than the errors introduced at high frequencies by limiters or AGC. This determines the increase in the accuracy of measuring the phase shift between short radio pulses in a large dynamic range of amplitudes.

Subject invention

A frequency-converted radio-pulse phase meter, containing reference and measuring channels, which are made of serially connected input devices, mixers and intermediate frequency amplifiers and connected to a phase detector loaded on a low-pass filter, as well as a local oscillator connected to both mixers, characterized in that in order to reduce the errors of measuring the phase shift between short radio pulses in a wide dynamic range of amplitudes, between the output of the local oscillator and the inputs of both mixtures A controlled attenuator is turned on, and the attenuator control circuit is composed of a series-connected resonant filter at twice the intermediate frequency, an amplitude detector and a feedback amplifier, the input of the resonant filter connected to the output of the phase detector, and the output of the feedback amplifier to the control input attenuator.