SU425124A1 - Phase meter - Google Patents

Description

one

The invention relates to phase-measuring technology and can be used in phase meters with frequency converters when measuring the phase shift of radio pulse signals for both repeated and single exposure to short radio pulses.

Known frequency conversion phase meters include mixers, a local oscillator, a device for automatic frequency control, a reference oscillator, filters, limit amplifiers, a phase detector and an indicator.

Such phase meters can work only if the signals at the phase meter inputs are continuous oscillations, since the device for frequency auto-tuning is sufficiently inertial and it takes a long time to trigger it and set the desired local oscillator frequency. For operation in a pulsed mode and even more so with a single exposure to short radio pulses with a duration of 0.1-10 msec, such phase meters are not suitable.

The disadvantages of phase meters should also include the need to manually adjust the local oscillator, since the device for automatic frequency control only works if the frequency of the signal at the output of the filter is close to the frequency of the reference oscillator. Manual tuning of the local oscillator allows you to set its frequency so that the automatic frequency control device will work.

The purpose of the invention is the measurement of the phase difference of the radio pulse signals for both repeated and single exposure, as well as automation of measurements.

This is achieved by introducing into the device two single-band modulators and a frequency divider, with one of the inputs of single-band modulators being connected to the outputs of the local oscillator and the others to the outputs of the reference oscillator, and the outputs of single-band modulators connected to mixers whose outputs are through filters and amplifiers connected to the third mixer, the output of which through the filter is connected to the input of the amplifier-limiter, to the output of which is connected the input of the frequency divider, the output connected to the phase detector, and the second input of the phase detector RA is connected to the output of the other force bodies -ogranichitel, connected to the input

reference generator, and the output of the phase detector is connected to the indicator.

The drawing shows a block diagram of the device. The device contains mixers 1, 2 and 3.

LO 4, single-band modulators 5 and G, reference oscillator 7, filters 8, 9 and 10, amplifiers 11 and 12, limit amplifiers 13 and 14, frequency divider 15, phase detector 16. indicator 17.

The inputs of the mixers 1 and 2 are supplied to the radio pulse voltage Ui Ui (t) cos (i) fc:

i) cos & t. Sinusoidal voltages with an output of a local oscillator 4 with a frequency of coi are fed to two single-pole modulators, which also receive sinusoidal voltages at a frequency of 52 from the outputs of the reference generator. The output of the modulator 6 is the voltage of the upper sideband (a)) /, the output of the modulator 5 is the voltage of the lower sideband

4 cos (sy, - Q) t.

The magnitudes of the stresses, Us and U, are taken equal to one to simplify subsequent trigonometric transformations. Thus, the voltage t / i and f / 3 are applied to the mixer 1, and the voltage t / 2 and and to the mixer 2. As follows from the theory of frequency conversion, at the outputs of the mixers there are oscillations of frequencies equal to the difference and sum of the frequencies of the input voltages (and only these components if the mixers are balanced). Figures 8 and 9 isolate the components of voltages having sum frequencies. These filters should be bandpass with a band from (UMIIH + U) ± Q to nd) max +

-f-coi ± Q, where Mmin and somax are the values of the minimum and maximum carrier frequencies of the input radio pulses.

The output voltages of filters 8 and 9 are amplified by amplifiers 11 and 12 in order to increase the sensitivity of the phase meter and to clarify the linear conversion in mixer 3. The output voltages I / s and Ue of amplifiers 11 and 12 are equal

and, Ki, (t) cos (o) + (Oj + I) - If 1;

f /, KU., (t} cos (o) + CO, - 2) t.

The coefficient L takes into account the loss of conversion in mixers 1 and 2, the transmission coefficients of filters 8 and 9, and the gain factors of amplifiers And and 12. It is assumed that the channels in the phase meter are the same. Some inequality of the coefficients C in the phase meter channels, due to the possible nonidentity of the nodes, does not reflect on his work.

The voltages V and f / e are fed to the inputs of the mixer 3, to the output of which a filter 10 is connected, tuned to the difference voltage frequency (/ 5 and / 7b. The voltage at the filter output is equal to

and, - (t) and (t) cos (2D - Wed).

This design is applied to the input of the amplifier-limiter 13, the output of which is a rectangular voltage of the type square wave with a constant amplitude. The gain of amplifier limiter 13 must be chosen so that the limit takes place at the minimum amplitude of the input voltages Ui (t) and f / 2 (0- The output voltage of the amplifier 13 is fed to the input of frequency divider 15. Measuring phase shift is radiated in voltage UT,

whose frequency is twice the frequency of the reference oscillator. Dividing the voltage f / 7 by frequency by 2 allows measuring the phase shift under investigation at the frequency of the reference generator O. The voltage of the first harmonic of the carrier frequency at the output of the frequency divider can be written as

f / s f / {0cos (2 / -). P2 /

The voltage at the output of the reference generator Ut UcQsut.

To measure the investigated phase difference

the t / g and f / g voltages must be applied to the phase detector, and to obtain the highest broadband and fast response (which in this case is very important, since the proposed phase meter is intended for

Measurement of the phase difference between short radio pulses) It is advisable to use an annular phase detector circuit. One of the input voltages of the phase detector 16, taken from the output of frequency divider 15, is already rectangular. Another voltage, from the output of the reference generator 7, for conversion into a rectangular shape is fed to the amplifier-limiter 14, from the output of which the rectangular voltage goes to another input of the phase detector 16. The average value of the current in the load of the phase detector is

/ - ()

where K, is the coefficient taking into account losses in the phase detector and determined by the values of the output resistances of the signal sources, diode resistances and the load of the phase detector;

and - amplitudes of rectangular voltages at the inputs of the phase detector;

d) - phase shift between the input voltages of the phase detector in our case d).

The output voltage at the load of the phase detector R will be equal to

.0- (- +).

Thus, when the phase shift is zero, as the phase shift changes from -180 ° to + 180 °, the output voltage of the phase detector varies linearly from 0 to 2 KUR.

The output of the phase detector is connected to the indicator, which can be used as an oscilloscope, the scale on the screen

which is calibrated in terms of the phase shift between the input voltages. With a single exposure to radio pulses, it is advisable to use an oscilloscope with an afterglow. In automatic measurements, the indicator is used as an indicator.

A high-speed digital voltmeter, from the output of which information in the form of a binary-decimal code is sent to a computer.

Subject invention

A phase meter containing mixers, a local oscillator, a reference oscillator, filters, amplifiers, amplifiers-limiters, a phase detector, an indicator, characterized in that, in order to measure the phase difference of radio pulse signals both at multiple and single exposure, as well as automate measurements, The phase meter is equipped with two single-band modulators and a frequency divider, with one of the inputs of single-band modulators connected to the outputs of the local oscillator, and others to the outputs of the reference oscillator, and the outputs of single-band modulators dinene to mixers whose outputs through filters and amplifiers are connected to a third mixer, the output of which through a filter is connected to the input of one amplifier-limiter, the output of which is connected to the input of a frequency divider, the output connected to one input of the phase detector, and the second input of the phase the detector is connected to the output of another amplifier-limiter connected to the reference oscillator, and the output of the phase detector is connected to the indicator.

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