RU2101715C1 - Phase meter for signals of high and ultrahigh frequency - Google Patents

Abstract

FIELD: instruments. SUBSTANCE: device has signal addition unit, envelope detector, processing unit, synchronization unit. Goal of invention is achieved by introduced second controlled digital phase shifter in addition to digital phase shifter which is present in state-of-the-art device. Different combinations of input controlled phase shifts corresponding to different voltage values at output of envelope detector are set in subsequent ticks of operation cycle. Their set is used by processing unit for generation of output value of phase meter. Vector combinations which are required for phase detection are generated serially and detected by same envelope detector. This results in possibility to suppress mismatch effects caused by two parallel detectors. EFFECT: increased precision of measurements. 2 tbl, 1 dwg

Description

 The invention relates to the measurement of the phase angle between electrical voltages of high or ultra-high frequency, in particular to phase meters with a controlled phase shifter at the input.

The closest in technical essence to the claimed is a phase meter [1]
The known phase meter contains a controlled discrete phase shifter 0 - 90 ^o , phase detector, switch, functional converter and synchronization unit. The measurement result is determined by the arc tangent conversion of the two voltages from the output of the phase detector, obtained and stored in two consecutive clock cycles, corresponding to two states of the controlled phase shifter 0 and 90 ^o .

 In the known phase meter, the phase detector is performed according to a balanced circuit comprising a difference sum block, two envelope detectors with quadratic characteristics, and a voltage subtraction unit (or voltage additions with the opposite polarity of the detectors switching on).

 For any imbalance in the phase detector, for example, due to the non-identity or relative instability of the characteristics of the envelope detectors in the known phase meter, measurement errors occur. To increase the sensitivity to the power level of the input signals in a known phase meter, a two-channel amplifier device should be used. The difference in the amplitude-phase characteristics of the gain channels also leads to measurement errors.

 An object of the invention is to increase accuracy.

 The stated technical problem is solved in that in the phase meter containing the synchronization unit, a functional converter, the output of which is the output of the phase meter, and connected to the first input of the phase meter are connected in series to the first controlled discrete phase shifter, the input of which is connected to the first output of the synchronization unit by the control signal, the addition unit signals, an amplifying device, an envelope detector, inserted between the second input of the phase meter and the second input of the signal addition block of the second control a removable discrete phase shifter, the input of which is connected to the second output of the synchronization unit by a control signal, the first and second synchronous drives, the inputs of which are connected to the output of the envelope detector, the outputs of which are connected to the first and second inputs of the functional converter, and the block for generating quadrature reference signals, the first and the second inputs of which are connected to the inputs of the first and second controlled discrete phase shifters, respectively, by a control signal, the first and second outputs of which are connected to moves the first reference signal and the second synchronous drives respectively.

 The operation of the proposed phase meter is illustrated by a block diagram and a description of the principle of operation.

 The block diagram shows 1 first phasemeter input, 2 second phasemeter input, 3 first controlled discrete phase shifter, 4 second controlled discrete phase shifter, 5 signal addition unit, 6 - amplifying device, 7 envelope detector, 8 first synchronous storage, 9 second synchronous storage , 10 functional converter, 11 block for generating quadrature reference signals, 12 — synchronization block 6 13 phase meter output, 14 processing block.

 The first controlled discrete phase shifter 3, the signal addition unit 5, the amplification device 6, the envelope detector 7 are connected in series to the first input of the phase meter 1, and the second controlled discrete phase shifter 4 is connected between the second input of the phase meter 2 and the second input of the signal addition unit 5. Inputs of the first and second synchronous drives 8, 9 are connected to the output of the envelope detector 7, and their outputs are connected to the first and second inputs of the functional Converter 10, the output of which is the output of the device 13. Pe the second and second outputs of the synchronization unit 12 are connected respectively to the inputs of the control signal of the first and second controlled discrete phase shifters 3, 4 and to the first and second inputs of the block for generating quadrature reference signals 11. The inputs of the reference signal of the first and second synchronous drives 8, 9 are connected respectively to the first and second inputs of block 11.

The phasemeter operates in cycles consisting of successive clock cycles. In each cycle, the synchronization unit 12 provides a certain, different from other cycles, combination of integer settings n 0,1,2,3 and m 0,1,2,3, which are output from the control signals of discrete phase shifters 3, 4 and the inputs of the block formation of quadrature reference signals 11. Nominal values of phase shifts created by controlled discrete phase shifters 3, 4 are multiples of π / 2
γ ₁ = nπ / 2; γ ₂ = mπ / 2.
A change in the phase shifts γ ₁ , γ ₂ causes a change in the amplitude of the signal at the output of the signal addition unit 5. The total signal is amplified by an amplifying device 6 and amplitude-detected by an envelope detector with a quadratic characteristic 7.

Synchronous drives 8 and 9 accumulate the signal coming from the output of the envelope detector 7 during the measurement cycle with the weights determined by the reference signal C _nm , S _nm coming from the block for generating the quadrature reference signals 11. The reference signals C _nm , S _nm vary in three discrete levels corresponding to 1.0, -1. In block 11, an unambiguous correspondence is ensured between the values of the integer settings n, m supplied to its inputs and the levels of the reference signals C _nm , S _nm generated at its outputs, in accordance with Table 1a, b.

In the general case, the quadrature reference signals C _nm , S _{nm are} proportional, respectively, to the cosine and sine of the difference in phase shifts γ ₁ , γ ₂ generated by controlled discrete phase shifters.

которое выдается на выход 13 фазометра как результат измерения разности фаз сигналов на входах 1, 2.Functional converter 10 converts the values of X, Y of the voltages supplied to its inputs from synchronous drives 8 and 9 into the value of the argument of the complex number ZX + jY:

which is issued to the output 13 of the phase meter as a result of measuring the phase difference of the signals at inputs 1, 2.

The principle of operation of the phase meter is based on using the relationship between the amplitude of the total signal at the output of the signal addition unit 5 and the phase difference of the signals at its inputs, which is composed of the known measured value φ of the phase difference of the signals at the inputs of the phase meter 1, 2 and the known value of the phase difference difference g ₁ , γ ₂ introduced by controlled discrete phase shifters. This dependence can be represented by the formula
A ² = a $\genfrac{}{}{0ex}{}{\text{2}}{\text{1}}$ + a $\genfrac{}{}{0ex}{}{\text{2}}{\text{2}}$ + 2a ₁ a ₂ cos [φ + (γ ₁ -γ ₂ )] (1)
where A is the amplitude of the total signal;
a ₁ , a ₂ - amplitudes of the summed signals;
γ ₁ , γ ₂ phase shifts introduced by controlled phase shifters.

In the presence of the necessary set values of γ _1, γ ₂ equations of the form (1) form a system of equations that can be solved for the unknown measured value φ most simple solutions occur when using the values g _1, γ ₂ multiples of π / 2 that is accepted in the proposed device.

 Vector combinations of the summed signals necessary for the implementation of phase detection in the proposed phase meter are formed sequentially in time. The total signal is amplified by the same amplifier and detected by the same envelope detector, due to which it is possible to fundamentally eliminate the unbalance effects inherent in known devices with two-channel construction and thereby increase the measurement accuracy. It is assumed that the switching rate in the proposed device is high enough to exclude dynamic measurement errors.

 There are various options for a specific technical implementation of the proposed device and its constituent units. For example, it is possible to organize a quasi-continuous mode of operation of the phase meter with repeated repetition of duty cycles during the measurement. In this case, synchronous drives 8, 9 should have an accumulation time constant that is significantly longer than the switching cycle time.

 The synchronization unit 12 in the simplest embodiment can be made in the form of a clock shaper and a binary counter. The outputs of the bits of the binary counter in some arbitrarily set order are connected one by one to the control inputs of the bits of the discrete phase shifters. There are other possible embodiments of the synchronization unit 12, provided that mutual orthogonality and balance are achieved on two discrete levels of the signals generated by it.

 The number of combinations of discrete states of the phase shifters 3, 4 and the corresponding number of clock cycles in the working cycle of the phase meter can be different in different versions of the technical implementation. The minimum required number of combinations (cycles) is 4. The highest accuracy of measurements is achieved in the balanced version of the phase meter using all 16 combinations of discrete phase shifts that are multiples of π / 2 created by two two-bit phase shifters connected at two inputs of the device.

 Blocks of synchronous drives 8, 9, a unit for generating quadratic reference signals 11, a functional converter 10 in the aggregate are a processing unit 14 of the signal from the output of the envelope detector 7. The processing unit as well as the synchronization unit 12 can be implemented on the basis of a digital microprocessor. In this case, an analog-to-digital voltage-code converter is introduced at the output of the envelope detector.

Claims (1)

The phase meter of high or ultra-high frequency signals, comprising a synchronization unit, a functional converter whose output is the output of the phase meter, and connected to the first input of the phase meter, are connected in series to the first controlled discrete phase shifter, the input of which is connected to the first output of the synchronization unit by a control signal, the signal addition unit through the first input, an amplifying device, an envelope detector, characterized in that it is inserted between the second input of the phase meter and the second input signal addition unit, a second controlled discrete phase shifter, the input of which is connected to the second output of the synchronization block by a control signal, the first and second synchronous drives, the inputs of which are connected to the output of the envelope detector, the outputs of which are connected to the first and second inputs of the functional converter, respectively, and the quadrature generation unit reference signals, the first and second inputs of which are connected to the inputs of the first and second controlled discrete phase shifters, respectively, by a control signal the first and second outputs of which are connected to the inputs of the reference signal of the first and second synchronous drives, respectively, while the signals at the outputs of the synchronization block are combinations of integer settings, the signals at the first and second outputs of the block for generating quadrature reference signals are proportional to the cosine and sine of the phase difference, respectively of shifts created by controlled discrete phase shifters, the signal φ at the output of the functional converter is determined from the expression

where X and Y are the signals at its first and second inputs, respectively.

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