SU112960A1 - Band phase meter - Google Patents

Description

Range phase meters based on pre-frequency conversion of the compared voltages and subsequent phase measurement between two other voltages at a constant frequency are known. The main disadvantage of such phase meters is the dependence of the measurement error on the amplitude of the compared input voltages.

In the described invention, one of the compared voltages obtained after conversion does not depend on the magnitude of the input voltage, as a result of which the dependence of the measurement error on the change in the amplitude of the input signals decreases and the accuracy of the measurements increases. For this purpose, the output of the local heterodyne is connected via a phase splitter and an uncalibrated adjustable phase shifter, with a phase indicator

The drawing shows a block diagram of the described phase meter.

One of the tested voltages

and sin ((u t -f cpi), taken from the channel output /., is fed to the mixer U. At the same

the mixer receives a signal from oscillator 2 stabilized by quartz. m L / r) (b -:., -). At the output of the mixer /, whose load is a band-pass filter 3. the difference frequency is released:: / Cf; rL /, sin (o) -). supplied to the second mixer 4. The second studied voltage is supplied from the channel output // L., - U., (.- r:.,., the load of this mixer is a resonant filter 5. tuned to the oscillator frequency 2. The difference frequency obtained at the output of the mixer 4 is determined by the expression

K Uf .-, .f +

(,) and equal to the frequency of the oscillator 2. The stability of the difference frequency is very high, since it is determined by the frequency stability of the crystal oscillator 2.

The phase difference between the oscillations of the generator 2 and the oscillations obtained at the output of the mixer 4 is equal to the phase difference between the voltages under study. Thus, the measurement of the phase difference of the two studied oscillations