SU600471A1 - Arrangement for testing meter of group time delay - Google Patents

Description

one

The invention is based on phase-measuring technology and can be used in instruments for calibration of group time delay meters (GDT), as well as in all cases where separate control (in amplitude and phase) of any of the components of an amplitude-modulated (AM) signal is required. or beat.

The known device for calibrating the metering devices contains dual capacitors, the rotors of which are brought into continuous rotation, and the stator rotation angle of one capacitor relative to another, measured with great accuracy, is a measure of the group deceleration time used for instrument calibration and has a small measurement accuracy 1.

It is also known another device for measuring the phase shift between two voltages MP, containing a generator, two rotary phase shifters, the rotors of which are located on the same shaft and inserted in continuous rotation, and a reading device connected to the stator of one of the phase shifters, and an inertial phase indicator. The compensating phase shift is also determined by the angle of rotation of the stator of one phase shifter relative to the stator of another 2.

Measurement of the GDT in such a device is possible only with the successive transmission of first one harmonic oscillation followed by the measured phase shift at the input and output of the object under study, and then the second, and the result of the measurement of the delay group

equal to the ratio of the differential phase shift to the difference frequency. Measuring Amsignal (consisting of three or two harmonic components) do not have such a threat, therefore it is impossible to determine the error in measuring the GDT arising from the non-ideality of amyl state-of-the-art frequency characteristics and phase-frequency characteristics of the studied objects. The aim of the invention is the new

accuracy of measurement of the group stop by determining the errors introduced by the phase response and the unevenness of the frequency response of the object under investigation. This is achieved by the fact that a device containing two circular phase shifters, the rotors of which are located on the same shaft, and the stator of the first phase shifters are mechanically connected to the readout device, and the master oscillator connected to the input of the second phase shifter is inserted into the vertical mechanism, which is connected cut, two bandpass filters, three attenuators, a phase shifter, a frequency filter and an adder, and a reference voltage generator is installed on the same shaft with an electric motor, and its output is through a low-pass filter and the limiter is connected to the output terminals of the device, and the outputs of each of the two other limiter amplifiers are connected through two successively connected band-pass filters and attenuators to the two inputs of the adder, the third input of which is connected to the output of the master, its generator and the input of the nerve circular phase shifter phase shifter and attenuator, the output of the adder is connected to the output terminals of the device, and the vernier mechanism is mechanically connected to the stator of the second phase shifter. The circular phase shifters are set so that the directions of rotation of their rotors relative to the electromagnetic field of the stators are opposite.

The device makes it possible to synthesize the measuring AM signal or bienn, to control its harmonic components separately but the amplitude on the phase, which makes it possible to determine the error of measuring the GD due to the frequency response and phase response of the instrument to be tested.

The drawing shows a block diagram of the proposed device.

It contains a master oscillator 1, the output of which is connected to the input of two circular phase shifters 2, 3, the rotors of which are located on the same shaft and are brought into continuous rotation by the electric motor 4, their stators are mechanically connected - one with the reading device 5, the second - with the vernier mechanism 6 and the outputs of the phase shifters are connected to the inputs of the limiting amplifiers 7, 8. A generator 9 of the reference voltage is installed on the same shaft with the electric motor, the output of which is through a low-pass filter 10 and a full amplifier-limiting device 11 dklyuchen reference input to forward power metal device 12, and outputs the main limiting amplifiers via respective series-connected band pass filters 13, 14, attenuators 15, 16 are connected to the two inputs of adder 17, whose output is connected to a measuring input power metal emogo device. The output of the master oscillator through the successively connected phase shifter 18 and the attenuator 19 is connected to the third input of the adder.

The principle of operation of the device is as follows.

If the rotors of circular phase shifters located on the same shaft are brought into continuous rotation and the stators are connected in such a way that the directions of their electromagnetic fields are opposite, then the frequencies of the output voltages of the phase shifters will differ by 2Q, i.e. the double rotation frequency of the rotors. These voltages, together with the master oscillator voltage, are applied to the linear adder, and the phases of all three voltages are aligned so that they are on the same straight line on the phase-response characteristic. With the correct choice of the amplitudes of the original paprigenes, it is possible to get a pa output of the adder A. M-voltage, in which any of its harmonic components is easily controlled both in amplitude and phase.

In case the measuring signal must consist only of the components of the two side frequencies, the voltage of the master oscillator carrying the oscillations a) on the adder

not served.

In the proposed device, the outputs of the circular phase shifters are preassigned to the inputs of the limiting amplifiers to suppress the parasitic amplitude moduli of their voltages. The following nolosovye filters isolate the nervous harmonic of the oscillations at the outputs of the limiter amplifiers, i.e. the frequencies co + d, co-Q, and feed them to the inputs of the adder. Driver voltage

a generator is fed to the input of an adder via a phase shifter and an attenuator in the event that an AM measurement signal is required.

A reference voltage generator is installed on the same axis with the rotors of the circular phase shifters and the electric motor. Its output signal (with a frequency Q), formed through a low-pass filter and a suppressor-limiter, as an instrument for a test instrument.

A novelty of the device by the proposed device (for the case of an M-measuring signal) is carried out as follows.

The counting device 5 of the circular phase shifter 2 is set to zero. Phaser 18 in the circuit of the oscillating oscillation establish a minimum of distortion at the output of the adder. The indicator is any oscilloscope or a scanned instrument itself, which is shown as the phases approach

all three voltages to the values that are on the phase-frequency characteristic on one straight line approach the minimum, and at any offset their location from the straight line increases. By rotating the stator of the generator 9 of the reference voltage, the zero readings of the instrument being calibrated are set.

By setting, using the readout device 5, any phase shift and again to achieve the minimum range of indications of the instrument being tested, by rotating the phase shifter 18 of the carrier oscillation, the readings of the instrument being checked are measured from the MP readout device, which can be scaled in units

of time.

By turning the stators of the circular phase shifters to one or different sides at a small angle, it can be determined by how much the readings of the scanned device change, due to the nonlinearity of its phase response. By replacing the amplitude of the lower or upper side frequencies of the measuring signal with an attenuator, it is possible to determine the accuracy of the instrument being tested, due to the frequency measurement of its frequency response.