SU1322179A1 - Method and apparatus for measuring small variations of phase difference - Google Patents

Abstract

The invention relates to the field of microwave measurements and can be used to build effective systems of phase direction finders, high-precision phase-tuning of the frequency of generators, as well as in systems where it is necessary to measure small changes in the phase difference of microwave signals. In the device that implements the method, Bridge 2 provides microwave signals, the change in the phase difference of which is measured. On the path of one of these signals, an adjustable phase shifter 1 is turned on to set the initial phase, where the maximum multiplication factor of the difference change takes place. phases. The mixed signals are modulated with a modulator 3 and 4 by a pulsed control voltage of a certain duty cycle, shifted in phase by. Then the signals are summed and. served on the adder 5, and from its output to the input of the quadratic detector 6 and then to the input of the selective amplifier 7. The value of the measured phases is obtained at the output of the phase meter 8. The drawing also shows the master oscillator 10 and the frequency doubler 9. The method provides an increase in sensitivity and an increase in the accuracy of measuring small changes in the phase difference. 2 s, p. f-ly, 3 ill. ro 1hE to

Description

43

The invention relates to microwave microwave measurements and can be used to build effective systems of phase finders to "high-precision phase-tuning of the frequency of generators, as well as to systems where it is necessary to measure small changes in the phase difference of the microwave signal

The purpose of the invention is to increase the sensitivity and increase the accuracy of measuring small changes in the phase difference.

Fig. 1 shows j HarpaNSMbi, explaining the temporal relations between the input signals and the resulting signal at the output of the device; in Fig. 2, the ratios between the multiplication factor of the phase difference Kg and the magnitude of the phase difference b t, -Cf; FIG. 3 is a block diagram of a device implementing a method.

The proposed method is carried out as follows.

Let the signals change the phase difference. which are to be measured are equal

j ("t + tp.)

E, E, E, E /

j (wt -Kf i)

where Ej 3 E, Cp,,

 cJ - respectively, the amplitudes, initial phases and the frequency of these signals,

After mixing, the signals are equal.

(E, -LE) and - (E, -jE,).

The modulation of these mixed signals is produced by pulsed voltages.

mi 5 out of phase by ---. After

modulation signals take the following form

f, (t) (E, jE, j) 5 - | -fj4t) (E, rjE,),

where fj, f ,, are the laws of signal modulation. The sum of the modulated signals 50

Ё -, (t) (E, -jE ,,) f, (t) (,),

Fia quadratic detector voltage output is as follows ;;

Up, HER,

t-de si; - parameter depending on the quadratic detector,

(Oi-i E (Eigp. 1. G (G

 -Mcos b -f-ra sin-S

   .but

ticosiZftt arctg (mtg5) j;

where and J J, C ,, m ctg2 | 3;

Y coefficient

booster.

Thus, at low get the value of the phase

P arctg (mtg5).

Multiplier factor phase difference

TO

- ..

4 d 5 t, 2. r p cos about + t sin about

Therefore, the coefficient of multiplication of the phase difference does not depend on the amplitudes of the microwave signals, and the desired value of the coefficient Kj can be obtained only by changing the duty cycle of the control pulses. The maximum value of the multiplication factor, equal to m, is obtained at values of S close to 0 or 180 °,

The graph of the multiplication function Ku is given for three values of m (Fig. 2),

At the maximum value of the multiplication factor, the signal amplitude

decreases in

 relative times35

Q

45

50

but a linear phase meter, instead of mra at best, in the known method, i.e. the sensitivity implemented by the proposed method of the device above,

Thus, to implement the proposed method, the microwave part and the type of modulation should be changed in the known device.

A device that implements the method (Fig. 3) contains a phase shifter i connected to one of the inputs of a slotted bridge 2, the outputs of which are connected via the modulators 3 and 4 to the inputs of the adder 5, to the output of which a quadratic detector b is connected. The output of detector 6 through selective amplifier 7 is connected to one of the inputs of phase meter 8, the other input of which through frequency doubler 9 is connected to the output of master oscillator 10. The output of master oscillator is also connected to the input of driver 1 of control pulses, which outputs 313

it is connected to the control inputs of the modulators 3 and A.

The device works as follows.

The inputs of the slot-hole bridge 2 are supplied with microwave signals, the change of the phase difference of which is to be measured. On the path of one of these signals, an adjustable phase shifter 1 is installed to set the initial phase, where the maximum value of the multiplication factor of the change in the phase difference occurs. The mixed signals at the output of the slotted bridge are modulated with the help of modulators 3 and 4 by pulsed control voltages of a certain duty cycle, shifted by

phase on -d modulated such

Thus, the signals are summed by adder 5 and fed to the input of a quadratic detector 6. The detected signal is fed to the input of a selective amplifier 7 tuned to twice the modulating frequency. The low-frequency signal from the output of the selective amplifier 7 and the low-frequency signal generated by the master oscillator 10 using frequency doubler 9 are fed to the inputs of the low-frequency phase meter 8. At the output of the phase meter, a phase value equal to

P arctg (mtgS),

where S 4, - ,;

m is a parameter depending on the wellness of the control pulses that are generated by the shaper 11. At values of S 0 and 180, the maximum coefficient of intelligent change in the phase difference equal to m is obtained.

Claims (2)

Formula invented and. A method for measuring small changes in phase difference, comprising 794 that one input signal is shifted in phase relative to the other by 90 and shifted, the resulting shifted signals modulate, acquire a low-frequency spectrum of the signal and measure phase shift signals, which, in order to increase sensitivity and increase exact - these measurements, the formation of mixed signals is made by adding half of one signal to half of the other, shifted 90 in phase, the modulation of the received signals is produced by low-frequency pulses of variable duty cycle, mixed with m relative about each other on ir / 2, and the resulting signal with the multiplied phase difference is obtained by summing the envelope of the modulated signals 2. A device for measuring small changes in the phase difference containing a phase shifter, a quadratic detector whose output is connected through a selective amplifier to a phase meter input, the second input of which connects the frequency doubler to the first output of the master oscillator, in order to increase the sensitivity and increase measurement accuracy; two modulators, an adder and a slot-hole bridge, as well as a driver of control pulses, the input of which is connected to the second output of the master oscillator, are introduced at this The first input of the slotted bridge is connected via a phase shifter to the bus of the first input signal, the thickness of the second input signal is connected to the second input of the slotted bridge, the first and second outputs of which are respectively connected via the first and second modulators to the inputs of the adder, the output of which is connected to the input of a quadratic detector a The first and second outputs of the control pulse driver are connected to the control inputs of the first and second modulators. Ig