RU2490660C1 - Scale converter phase error meter - Google Patents

Abstract

FIELD: instrument making.

SUBSTANCE: proposed meter comprises test signal controlled source, tested scale converter, first and second frequency inverters, first and second limiting amplifiers, microcontroller phase detector and LC indicator. Besides, it includes extra scale converter and controlled signal switch.

EFFECT: higher accuracy of measurements.

1 dwg

Description

The invention relates to measuring equipment and can be used to determine the phase errors of large-scale converters designed to operate in a wide frequency and dynamic ranges of input signals.

Direct measurement of the phase error of the scale converters by phase-sensitive devices (phase meters) by comparing the phases of the input and output signals of the controlled scale converter is difficult, since the phase meters have a significant phase-amplitude error. It is generally not possible to separate it from the phase error of the scale converter in the general case [Klaassen KB The basics of measurements. Electronic methods and devices in measuring equipment. M .: Postmarket. - 2002. - 352 p.].

A compensation device is known comprising a reference and controlled voltage divider, a phase shifter and phase comparison circuits, phase shifts of the controlled dividers are measured with respect to the reference voltage divider using a phase shifter [Kushnir F.V., Savchenko V.G., Vernik S.M. Measurements in communication technology. M .: Communication. - 1976. - 332 p.].

The absence of exemplary phase-shifting voltage dividers for a wide frequency range does not allow measuring small phase shifts of wide-band voltage dividers in a wide frequency range, which affects the accuracy of measurements.

A device for measuring the phase shift of harmonic signals containing a pulse shaper, a second division unit, a differentiation unit, a first and second sampling and storage units, a first division unit, a first and second comparators, a trigonometric converter, a reference voltage source, an amplifier with an adjustable transmission coefficient, an adder with corresponding connections (RF patent No. 2103698, IPC G01R 25/00). The main disadvantage is that this device only solves the problem of determining the dependence of the phase shift of the four-terminal network on the frequency of the signal under investigation, moreover, in the kilohertz range, where phase ratios can be measured from instantaneous samples of the signals under study.

If scale converters operate in the frequency range where phase shifts can only be measured with frequency conversion of the signals under study, then the intrinsic phase-amplitude error of the frequency converter is dominant, at the level of which it is almost impossible to estimate the phase error of the scale converter.

The phasometer [USSR copyright certificate No. 960657, IPC G01R 25/00] was taken as the closest analogue. It contains attenuators, frequency converters, selective amplifiers, limiter amplifiers, phase detectors, AND element, recounting elements, a reversible counter, a digital recording unit, a control unit, a crystal oscillator, controlled oscillators, a divider. In the device for eliminating the phase-amplitude error of frequency converters, the measurement process is carried out with a change in the frequency of the controlled generator (local oscillator) from ω _Г1 = ω _OP -ω _P to ω _Г2 = ω _OP + ω _P , where: ω _OP is the frequency of the reference signal, _F ω - frequency of the LO signal, ω _P - frequency difference signal, and since the sign of the phase error amplitude-frequency inverter does not change (since the change in frequency controlled oscillator signal amplitudes no change occurs), then comparing the two measured results th phase shift can be separated from its own error phase meter.

However, when studying a scale converter, in addition to the need to eliminate the phase error of frequency converters, the problem arises of minimizing the error of measuring the phase shift already at an intermediate frequency, due to the large inequality of the amplitudes of the input and output signals of the scale converter.

Thus, the disadvantages of the prototype include insufficient accuracy of the measurement of phase errors of large-scale converters.

The technical result of the claimed invention is to increase the accuracy of measuring phase errors of large-scale converters.

The technical result is achieved by the fact that the proposed phase error meter consists of a controlled source of test signals, a scale converter under investigation, a first frequency converter, a second frequency converter, a first and second limiting amplifier, a phase detector, a microcontroller, and a liquid crystal indicator. The device is equipped with an additional large-scale converter and a controlled signal switch.

The first output of the controlled source of test signals is connected to the input of the investigated scale converter and the signal input of the second frequency converter. The second output of the controlled source of test signals is connected to the heterodyne inputs of the first and second frequency converters. The output of the investigated scale converter is connected to the signal input of the first frequency converter, the output of which is connected through the controlled signal switch to the input of the first limiter amplifier, the output of which is connected to the input of the phase detector. The input of the additional large-scale converter is connected to the output of the second frequency converter, and its outputs are connected to the input of the controlled signal switch and to the input of the second amplifier-limiter, the output of which is connected to the input of the phase detector. The output of the first frequency converter is connected to the input of a controlled signal switch, the output of which is connected to the input of the first limiter amplifier.

The difference between the proposed phase error meter of the scale converter and the prototype lies in the fact that it additionally introduces a controlled signal switch and an additional scale converter. These additional elements make it possible to measure the phase error of the phase-compared signals that are previously aligned in amplitude due to the organization of the switching algorithm provided by the corresponding connections and, accordingly, exclude the meter’s own phase error and, therefore, increase the accuracy and reliability of the phase error measurement.

The drawing shows a functional diagram of a phase error meter scale Converter.

The phase error meter of the scale converter 1 consists of a controlled source of test signals 1, connected to the studied scale converter 3 by the first output. The first frequency converter 4 is connected to the studied scale converter 3 by a signal input 3, and then in series with the controlled signal switch 5, the first amplifier-limiter 6 , phase detector 7, microcontroller 8, liquid crystal indicator 9.

The controlled source of test signals 2 is connected by its second output to the heterodyne input of the first frequency converter 4 and to the heterodyne input of the second frequency converter 10, whose signal input is connected to the first output of the controlled source of test signals 2, and the output is connected to the input of an additional scale converter 11, the output of which connected to the input of the controlled signal switch 5 and to the input of the second amplifier-limiter 12, the output of which is connected to the input of the phase detector 7. Micro 8 MODULES their outputs connected to the control input test signal source 2 and the controlled switch 5 signals.

The phase error meter of the scale converter operates as follows.

From the first output of the controlled source of test signals 2 of the phase error meter of the scale converter 1, a reference signal is supplied to the studied scale converter 3, from the output of which a signal is fed to the signal input of the first frequency converter 4, a heterodyne signal from the second output of the controlled source is fed to the heterogeneous input of the frequency converter 4 test signals 2. From the output of the first frequency converter 4, the differential frequency signal is fed to the first input of the controlled a signal switch 5, the second input of which receives a signal from the output of an additional scale converter 11, the input of which from the output of the second frequency converter 10 receives a differential frequency signal generated by the second frequency converter 10, the signal input of which receives a reference signal from the first output of a controlled test source signals 2, and the local oscillator receives a heterodyne signal from the second output of the controlled source of test signals 2. From the output of the managed switch Signals 5, the signals are fed to the first amplifier-limiter 6, from the output of which to the first input of the phase detector 7. To the other input of the phase detector 7 is the signal from the output of the second amplifier-limiter 12, to the input of which the signal from the output of the additional scale converter 11 is output phase detector 7, a signal proportional to the phase difference is fed to the input of the microcontroller 8, from the output of which, the signal is fed to the input of the liquid crystal indicator 9.

The measurement of phase errors occurs in 2 cycles, each of which consists of 2 clock cycles and is generated by the signals from the microcontroller 8, which are fed to the inputs of a controlled source of test signals 2 and a controlled signal switch 5.

In the first measurement cycle, the signals at the input of the investigated scale converter 3, at the heterodyne input of the first frequency converter 4 and at the input of the additional scale converter 11 are as follows:

$$\begin{array}{l}{U}_{\mathrm{ABOUT}P}\left(t\right)=U_{\mathrm{ABOUT}P}sin\left({\omega }_{\mathrm{ABOUT}P}t+{\varphi }_{\mathrm{ABOUT}P}\right)\\ U_G\left(t\right)=U_{G}sin\left({\omega }_{G}t+{\varphi }_G\right)\left(\mathrm{one}\right)\\ U_P\left(t\right)=U_{P}sin\left({\omega }_{P}t+{\varphi }_P\right)\end{array}$$

where: U _OP is the amplitude of the reference signal, ω _OP is the frequency of the reference signal, φ _OP is the initial phase of the reference signal, U _G is the amplitude of the heterodyne signal, ω _G is the frequency of the heterodyne signal, φ _G is the initial phase of the heterodyne signal, U _P is the amplitude difference signal, ω _P is the frequency of the difference signal, φ _P is the initial phase of the difference signal. The frequency of the heterodyne signal ω _G at the second output of the source of test signals 2 is set equal to:

$${\omega }_G={\omega }_{\mathrm{ABOUT}P}-{\omega }_R\left(2\right)$$

Then, in the first step of the first measurement cycle at the output of the phase detector 7 we have:

$${\varphi }_{\mathrm{one}}={\varphi }_{\mathrm{AND}MP}+{\varphi }_{PH}+\Delta {\varphi }_{PH}-{\varphi }_D+\Delta {\varphi }_f+\Delta {\varphi }_U\left(3\right)$$

where: φ _IMP - the measured phase shift of the investigated scale Converter; φ _IF - phase shift of the frequency converter 4, due to the difference in the amplitude of the signals at the signal and heterodyne inputs; Δφ _IF - the phase difference of the frequency converters at the initial signal levels at the signal and heterodyne input, taking into account the initial phases φ _G and φ _OP ; φ _D is the phase shift of the additional scale Converter 10; Δφ _f is the phase difference of the amplifier-limiters, due to the non-identity of their phase-frequency characteristics; Δφ _U is the phase difference of the amplifier-limiters, due to the non-identity of the phase-amplitude characteristics.

In the second cycle of the first measurement cycle, from the output of the additional scale converter 11, the signal is fed to the input of the amplifier-limiter 12 and through a controlled signal switch 5 to the input of the amplifier-limiter 6, and the measurement result at the output of the phase detector 7 is equal to:

$${\varphi }_2=\Delta {\varphi }_f+\Delta {\varphi }_U\left(\mathrm{four}\right)$$

Compare the results in both measures for the first measurement cycle, we have:

$${\varphi }_{\mathrm{Ts}\mathrm{one}}={\varphi }_{\mathrm{one}}-{\varphi }_2={\varphi }_{\mathrm{AND}MP}+{\varphi }_{PH}+\Delta {\varphi }_{PH}-{\varphi }_D\left(5\right)$$

In the second measurement cycle, the frequency of the heterodyne signal ω _G at the second output of the source of test signals 2 is set equal to:

$${\omega }_G={\omega }_{\mathrm{ABOUT}P}+{\omega }_R\left(6\right)$$

Then, in the first step of the second cycle, the measurement result at the output of the phase detector 7 will be calculated by the formula:

$${\varphi }_3=-{\varphi }_{\mathrm{AND}MP}+{\varphi }_{PH}+\Delta {\varphi }_{PH}-{\varphi }_D+\Delta {\varphi }_f+\Delta {\varphi }_U\left(7\right)$$

In the second cycle of the second cycle, from the output of the additional scale converter 11, the signal is fed to the input of the amplifier-limiter 12 and through a controlled switch of signals 5 to the input of the amplifier-limiter 6, and the measurement result at the output of the phase detector 7 will be defined as equal to:

$${\varphi }_{\mathrm{four}}=\Delta {\varphi }_f+\Delta {\varphi }_U\left(8\right)$$

Comparing the results in both measures of the second measurement cycle, we have:

$$$$

$${\varphi }_{\mathrm{Ts}2}={\varphi }_3-{\varphi }_{\mathrm{four}}=-{\varphi }_{\mathrm{AND}MP}+{\varphi }_{PH}+\Delta {\varphi }_{PH}-{\varphi }_D\left(9\right)$$

Comparing the measurement results of the first and second measurement cycles, we obtain:

$$\Delta {\varphi }_{\mathrm{Ts}}={\varphi }_{\mathrm{Ts}\mathrm{one}}-{\varphi }_{\mathrm{Ts}2}=2{\varphi }_{\mathrm{AND}MP}\left(10\right)$$

We find the measured phase shift of the investigated scale Converter 3:

$${\varphi }_{\mathrm{AND}MP}=\frac{\mathrm{one}}{2}\Delta {\varphi }_{\mathrm{Ts}}\left(\mathrm{eleven}\right)$$

Thus, the introduction of an additional scale converter to the measurement circuit, which makes it possible to equalize the levels of the studied signals and a controlled signal switch that implements the switching algorithm of the phase information meter, allows the elimination of phase-amplitude and phase-frequency errors of limiter amplifiers and thereby increase the accuracy of phase measurement shear scale converter. At the same time, the introduction of appropriate measurement cycles in the measurement process eliminates the intrinsic phase error of the additional scale converter. In general, these differences make it possible to solve the problem of measuring the phase error of large-scale converters independent of the error of the phase measuring device.

The proposed technical solution is new, has an inventive step and is industrially applicable, i.e. satisfies the criteria for inventions.

Claims (1)

Phase error meter, consisting of a controlled source of test signals, a studied scale converter, first and second frequency converters, first and second limiter amplifier, phase detector, microcontroller, liquid crystal indicator, characterized in that the device is equipped with an additional scale converter and a controlled signal switch, the first output of the controlled source of test signals is connected to the input of the studied large-scale pre the generator and the signal input of the second frequency converter, the second output of the controlled source of test signals is connected to the heterodyne inputs of the first and second frequency converters, the output of the investigated scale converter is connected to the signal input of the first frequency converter, the output of which is connected through the controlled signal switch to the input of the first limiter amplifier, the output of which is connected to the input of the phase detector, the input of an additional scale converter is connected to ode to the second frequency converter, and its outputs are connected to the input of the controlled signal switch and to the input of the second amplifier-limiter, the output of which is connected to the input of the phase detector, which is connected in series with the microcontroller and the liquid crystal indicator, in addition, the microcontroller is connected with its controlled outputs with a controlled test signal source and a controlled signal switch.