SU681388A1 - Digital phase meter - Google Patents

Description

(54) DIGITAL

The device is characterized by low accuracy of phase difference measurement due to different electrical channel lengths (the first channel is longer than second by the electrical length of the electronic phase shifter), the nonlinearity of the frequency phase characteristics of the electronic phase shifter and the frequency instability of the generator in the frequency difference selection circuit, which is counted by a frequency meter, and also insufficient limits of the measured phase difference.

The purpose of the invention is to expand the range of measurement of the phase difference and improve the measurement accuracy.

This is achieved due to the fact that in the device containing in two channels serially connected mixers and limit amplifiers, common for two channels of the local oscillator with an automatic frequency control system, the third mixer, the output of which is connected to the digital frequency meter input, is an electronic phase shifter, the first input of which is connected to the output of the amplifier-limiting device of the first channel, the second input is connected to the first input of the third mixer, its output connected to the input of the digital frequency meter, and the output of the electronic phaser By connecting the first input of the phase lock loop system, trans

The output of which is connected with the third input of the electronic phase shifter, a second electronic phase shifter is additionally introduced, the first input of which is connected to the output of the second channel amplifier limiter and the input of the automatic frequency control system, the second input is connected to the second input of the third mixer, the third input is connected to the second output of the system phase self-tuning, -a output of the second electronic phase shifter is connected to the second input of the auto-phase adjustment system, the third and fourth inputs of which are connected to the output of the automatic tuning system stoty.

The drawing shows the structural scheme of the proposed digital phase meter.

It consists of mixers 1 and 2, limiting amplifiers 3 and 4, a common local oscillator 5 with an automatic frequency control system 6, which includes an intermediate frequency control switch 7, 8 tons (oscillatory circuits) 8 and 9, symmetrically viewed with respect to the intermediate frequency .1, adder 3.0, amplitude detector 11, low-frequency amplifier 12 of alternating voltage, phase detector (low-frequency synchronous detector). 13, the integrating filter 14 and the

torus reference voltage 15, electronic phase shifters 16 and 17, consisting of mixers 18, 19, O, 21, delay lines 22, 23 of controlled local oscillator 24 in the first channel and controlled local oscillator 25 in the second channel;

the phase locked system 26, including the intermediate frequency controlled switch 27, the phase-shifting circuits 28 and 29

 phase shift at the daily rate, respectively, at Tt and If / 2, combiner ZO, amplitude detector 31, low-frequency amplifier 32 of alternating voltage (error signal), phase detector

(low-frequency 1-phase detector) 33 and integrating filters 34 and 35, mixer 36 and digital frequency meter 37.

The device works as follows.

In the initial state, the reference voltage generator 15 generates, for example, a rectangular voltage (square wave)

4 kHz frequencies to controllable switches 7 and 27, as well as to low-frequency phase detectors 13 and 33 systems of automatic frequency control 6 and phase 26. Managed hetero-

The 24 and 25 electron phase shifters are tuned to the same frequency, therefore the difference frequency oscillations at the Mixer Output 36, and therefore at the Input of the digital frequency meter 37 operating in continuous mode, for example, with a 1 M sec counting time. By connecting sources to the digital phase meter inputs

Claims (1)

The high-frequency oscillations, the phase difference between which is to be measured, adjust the common local oscillator 5 to the appearance of 3,4 signals at the outputs of the limiters. A part of the signal from the amplifier-limiter 4 is fed to switch 7, from the outputs of which through symmetrically distant relative to the intermediate frequency of Flash 8 and 9, the right impulses are alternately fed to the adder 10. From the last continuous mode, the oscillation is at the amplitude (frequency, oscillation), and the oscillation is alternating (variable, the amplitude of the oscillation) and the shape of the molar line coincides in frequency and shape with the voltage of the generator 15, the depth of modulation determines the amount of detuning in frequency, and the synphasic or anti-fangeness of the bend in relation to the voltage of the generator 15, to How frequency offset is detected. The selected bend is amplified and fed to the low-frequency phase detector 13, the constant component of which is outputted through the integrating filter 14. It enters the tunable common local oscillator 5, thereby ensuring the stabilization of the intermediate frequency. The intermediate frequency signals from the Outputs of the limiting amplifiers through Electronically controlled phase shifters 1 and 17, respectively, arrive at the input of the voltage controlled GOT and switch 27 and phase-shifting circuit 29. Rectangular radio1 pulses of the intermediate frequency from the outputs of the switch 27 alternately in phase or anti-phase (provided by the phase-shifted circuit 2 with respect to the input signal is fed to the input of the adder 30, the third input of which from the output of the phase-shifting circuit 29 (provides a phase shift to the continuous Intermediate frequency oscillation of the second channel. From the output of the AO adder, continuous amplitude-modulated oscillation of the intermediate frequency (frequency and modulation forks coincide in frequency and form with generator voltage 15, modulation depth determines the amount of phase detuning, and synphasis or antiphase the envelope with respect to the voltage of the generator — the sign of the phase alignment is detected. The selected bend is amplified and fed to the low-frequency phase detector 33 in the same way as in the auto-tuning system. - ki frequency. Antiphase voltages (opposite voltage) from the opposite pads of the low frequency arms of the phase detector 33, through identical integrating filters 34 and 35, arrive at the corresponding Inputs of the controlled local oscillators 24 and 25 of the electronic phase shifters 16, 17 and compensate for the phase difference of the signals at the intermediate frequency at their inputs. As a result of mixing the frequency-mixed cole C of the controlled local oscillators 1c and 17, the difference frequency is determined, the frequency is selected, and the C, the measured phase difference is measured by the digital frequency meter 37. The change in the phase difference at the Phasometer Inputs is automatically monitored by the system self-tuning of the 2G phase and two electron yppaB eFfl phase shifters 16, 17 ,. and the corresponding digital readout and the indicator of a digital frequency meter 37 correspond to it. According to the proposed digital phase meter circuit, a laboratory c-1 kit was made, which proved its efficiency before the prototype. Thus, the sensitivity was obtained (from the measured phase difference), which is a fraction of a degree (this was obtained without adopting / reducing the noise figure in the frequency and phase control systems), measuring the phase difference of -41 ° with the nonlinearity of the characteristic phase difference at the input phase meter - phase difference phase indicated by a digital frequency meter in the order of 5 to 7 ° (this nonlinearity is due to the low frequency properties of the gauge line used in electronic phase shifters 16 and 17, the frequency stabilization factor 1000. It should be noted that disconnecting the input of the controlled local oscillator of one of the electronic phase shifters from the phase auto-tuning system, which corresponds to the prototype in measuring sensitivity, limits on measuring phase difference and nonlinearity, characterizes the phase difference to approximately two times, narrowing the limits on measuring phase difference to - 240 ° - (- 190 °) and increasing the nonlinearity to 18-20 It should be noted that according to the scheme of the proposed qi of the Groove phase meter, devices can be constructed not only for measuring the difference phases between continuous high-frequency PI waves, but also between high-frequency pulsed oscillations (between radio pulses), for which a synchronizer and controlled peak detectors must be introduced into the device, which must be switched on between the detector and amplifier in each of the frequency and phase automatic tuning systems . DETAILED DESCRIPTION OF THE INVENTION Digital phase meter, goder, channel, sequential channel.