SU602877A1 - Radio pulse signal phase shift meter - Google Patents

Description

(54) DEVICE FOR MEASURING THE DIFFERENCE PHASES OF RADIO IMPULSE SIGNALS

memory, control element - connected to a tunable generator, outputs of a tunable channel generator are connected respectively to the first and second inputs of the measuring pulse generator, besides the output of a tunable generator to the second channel is connected to the heterodyne input of the same channel mixer, input to the delay line of the first channel through a series-connected amplitude detector and a limiting amplifier, it is connected to the control inputs of the keys of the slab channels.

The block diagram of the proposed device is shown in the drawing and contains the input blocks 1 and 2 of each channel, the lines of the 3 and 4 channels of each channel, the amplitude detector 5 force limiter 6, the mixers 7/8 of each channel, phase detectors 9, 10 each of the channels, reference generator 11, keys 12 and 13, memory unit 14, 15 of each channel, control elements 16, 17 of each channel, tunable generators 18, 19 of each channel, shaper of measuring pulse 20 and indicator 21.

The device for measuring the phase difference is made according to a symmetrical two-channel scheme.

In the first channel, the mixer 7, the phase detector 9, the key 12, the block 14, and the generator 18 with the element 16 form the following phase system (SPS). In the second channel, similarly: the mixer 8, the phase detector 10, the key 13, the block 15 and the generator 19, together with the control element 17, also form an SPS loop,

The SPS loop is closed with a key device for the duration of the input radio pulse, and at the time of its absence it opens, and the block 14 keeps the voltage on the element 16, and therefore the frequency and phase of the generator 18, unchanged. The operation of the key is controlled by the front and rear edges of the video pulse formed from an input radio pulse of one of the channels by a chain consisting of block 1, detector 5 and amplifier-limiter 6 radio pulses, between high-frequency fillings of which it is necessary to measure the phase shift, through the input units 1 and 2 and the delay lines 3 and 4 are fed to the input of mixers 7 and 8. Signals from the corresponding generators 18 and 19 are sent to the heterodyne input of the mixer of each channel, and from the outputs of mixers 7 and 8 the signals of the intermediate frequency follow the inputs detectors 9 and 10, the second inputs of which receive a generator signal 11 A device for correcting the initial detuning of the generator frequency 18 (19) r 7 Ozvol / 1et adjustment to obtain the intermediate frequency at the mixer output t

(8), close to the frequency of the reference generator 11, and, therefore, to ensure the performance of SPS.

The output signals of the phase detectors 9 and 10 are fed through keys 12 and 13 to blocks 14 and 15, which may be conventional capacitance. The voltages from the output of blocks 14 and 15 determine the magnitude of the capacitance of the varicaps used as elements 16 and 17, and

therefore, the frequency and phase of the signal

generators 18 and 19. The signal from the output of each generator ator 18 and 19 is fed to the heterodyne input of the corresponding mixer and with the closed key 12 and

13 century. Each channel forms SPS. SPS works out the initial detuning of the SH inlet of the detectors 9 and 10 in the capture mode with the cosinusoidal characteristic of the phase detector.

F arc cos yats / ya,

where SZy is the retention band of the system;

fy is the established value of the systematic phase error. The phase error of Chu can be eliminated by the device for correcting the initial detuning of the frequency during the measurement process. The phase difference of the input signals of the blocks 1 and 2 and the signals of the generators 18 and 19 are processed in the first approximation according to the law.

U 4 Ct)% expK (f 02) 1

where fd is the initial phase difference between the input signal and the tunable generator;

 02) - derivative characteristic of the phase detector at the operating point of CH, 2 .;

. 2 - steady state phase difference.

The basic requirement for SPS in the proposed device is the following speed requirement:

,,

where SC - the duration of the input radio pulses;

tycT is the time during which the transient process in the system almost ends.

For example, L4OD Yyst As a result of the SPS system working off the phase difference of the input radio pulse and tunable generator at the output of generators 18 and 19, the phase of continuous harmonic oscillations with some error Af is equal to the phase of the input radio pulse of the corresponding channel.

Claims (1)

J The error of DF is the sum of the errors of the LFM. -Gy. and the phase error introduced by the input device and the mixer, the latter components being compensated with the appropriate selection of elements in the channels at the output of the phase meter. At the end of the radio pulse, the keys 12 and 13 break the SPS circuits, and the memory blocks keep the voltage level that was at them at the time of the end of the radio pulse and, therefore, the frequency and phase of the generators 18 and 19 will remain unchanged for a time T equal to the period of the following radio pulses. The phase difference of continuous g mono oscillations at the output of the generators 18 and 19 can be measured with high accuracy by commercially available instruments. If the radio signal does not change from pulse to pulse, then averaging can be performed over a long period of time, determined by the required measurement accuracy, otherwise, the difference of continuous oscillations from the output of the generators 18 and 19 should be measured during time T which at large duty cycles of radio pulse signals is much longer than the duration of the radio pulse signals is much longer than the duration of the radio pulse. In the proposed device, the measurement of the phase difference of the signals from the outputs of the generators 18 and 19 is carried out in a block consisting of a series-connected shaper 20 and an indicator 21. Delay lines 3 and 4 are introduced in order to compensate for the delay of a video pulse in a circuit consisting of the detector 5 and the amplifier-limiter b, as in the case of a mismatch between the arrival times and the end of the radio pulse with the opening and closing times of the keys 12 and 13 there will be significant measurement errors due to changes in the voltage level in the Memories 14 and 15. Formula of the Invention A device for measuring the phase difference of a radio pulse signal, comprising a series connected measuring pulse generator and an indicator, a reference generator and two channels, each of which consists of a series-connected input mixer unit and connected to the heterodyne input of the first mixer of a tunable generator, characterized in that, in order to increase accuracy, it is equipped with an amplitude detector, an amplifier-limiter and in each of two channels a delay, a phase detector, a key, a memory unit, a control element and in the second channel an additional tunable generator, in each of the channels between the output of the input unit and the mixer input there are connected delay lines, the outputs of the mixers are connected to the first inputs of the phase detectors, the second inputs which are connected to the reference generator, the output of the phase detectors, respectively: through a serially connected key, recall unit, control cadmium element connected to a tunable generator , the outputs of the aaeivftix generators of each channel are connected respectively to the first and second inputs of the measuring pulse generator, in addition, the output of the second channel tunable generator is connected to the heterodyne input of the same channel mixer, the input channel of the first channel's cut-off line and the limiter amplifier connected to control by key inputs of both channels.