SU1741089A1 - Method of measurement of introduced phase errors of discrete binary phase inverter - Google Patents

Description

The main disadvantages of these methods are the low speed of measurement of phase errors, determined by the need for sequential switching, and then measurement in all discrete phase states of the phase shifter, as well as a sufficiently long time for calibration; the impossibility of measurements at a high power level, which, taking into account the peculiarities of the operation of switching elements in intensive microwave fields, reduces the reliability of the result, the large size and high cost of jobs for measuring phase characteristics,

The closest in technical essence to the present invention is a method based on an instrument for measuring the microwave signal vector ratios. In the device, the signal supplied from an external source is divided into two channels: reference and measurement. The reference channel is used as a calibration signal, the signal in the measuring channel is used as a probe channel for supplying the object to the test. . The frequency converter uses a primary conversion of the input signal to a frequency of 20 MHz, which is synchronized with the sig- nal oscillator signal, and the secondary one to the 55 kHz frequency at which the indicator unit operates.

The known method is peculiar to the list. Above the disadvantages (, 00, speed of measurement is 15 s), In addition, the limitation on the power level of the SBCh mW generator leads to a goma. - that the measured phase errors may differ from those introduced in actual operation conditions, under which the power can reach 10 watts and more.

The purpose of the invention is to reduce the measurement time and achieve the possibility of measuring phase errors at a high power level.

This goal is achieved by the fact that, according to the proposed method, a microwave signal is supplied to the microwave input of the phase shifter, and to the control inputs - control voltages with a duty cycle of 0 2 synchronized along the front or in the decay, the period of which with increasing bit number multiplier binary phase shifter is halved, measure the amplitudes of the spectral components of the output signal, which determine the introduced phase errors, while the minimum period of the control voltage applied to the first p az0

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a series of a multi-bit binary phase shifter is chosen 50 or more times the sum of the front and herd durations, and the phase error introduced by the nth bit is determined by the amplitude () of the harmonic of the output spectrum.

In the case of synchronization of the control pulses, on a decay, negative harmonics are analyzed, in the case of synchronization on the front, positive harmonics.

The proposed measurement of the phase characteristics of the phase shifter is based on the fact that there is a strict mathematically and physically sound connection between the phase errors of each discrete phase shifter and the magnitude of the harmonics of the output spectrum. Switching in the meander discharge mode Dtg provides suppression in the output signal spectrum of even harmonics, first of all the carrier (the so-called phase-shift keyed signal). The amount of suppression depends on the phase error of the Atg discharge and on the inequality of the durations of the phase states 0 and 7f. All these factors increase the level of even harmonics. To eliminate the effect of the inequality of durations, the frequency of the control pulses in the proposed method is set to be quite small.

(DO 0,02-t-g- in connection with which the duration t Tep

transient processes do not exceed 2% of the duration of phase states,

Thus, with these effects on the microwave signal, the level of the carrier harmonic during phase shift is a function of the phase error. It is known that with ideal phase manipulation, i.e. when the phase error is Dr 0, the carrier and all four harmonics are completely suppressed, with & j0 0.5 ° - carrier suppression 51 dB, with & 1 ° - carrier suppression 45.5 dB, with Dr 2 ° - 39.3 dB, etc. Thus, there is a monotonous unambiguous relationship between carrier suppression and & p with an average steepness of 6 dB / deg with errors up to 3 °, 3 dB / deg with errors of 3-6 °, 1 dB / deg with errors of more than 6 ° , which makes it possible to estimate the phase error by analyzing the output signal spectrum.

The accuracy of measuring the level of harmonic components of the spectrum using modern spectrum analyzers does not exceed 0.5 dB, i.e. The methodological absolute error of measurement of the phase error does not exceed 0.1 °. Obviously

that the estimation of the phase error of the discharge & k can be carried out using other even harmonics, but this is less convenient due to their lower level (in power).

Phase errors of the lower order bits are measured similarly.

When digitally switching an n-discrete phase shifter (in the case of synchronization of control pulses on the front or on the slope), the dependence between the connected next bit and a number of harmonics in the output signal spectrum suppressed with its help: the first bit E provides harmonic suppression with n 0 ± 2k (this has already been noted above), the second bit (D / 2) - with n -1 ± 4k; the third bit (A / 4) - with n -3 ± 8k; fourth bit (A / 8) - with n -7 ± 16k; Fifth bit (D / 16) -c n -15 ± 32k, where n is the harmonic number in the output signal spectrum, k 0, 1, 2, 3, 4, ...

The dependences are characteristic for the case of synchronization of control pulses with a decay. In the case of synchronization along the front, the dependences have a mirror-like appearance, which allows maintaining common reasoning.

In order to achieve the stated objective of the invention, the harmonics with the smallest number are selected from the given series for measuring the phase error: for A = n 0; for Atg / 2 - n -1 (or +1); for D / 4 - n ± 3; for A / 8, n ± 7; for D / 16 - n ± 15; those. The p (1,2, ...) bit corresponds to the harmonic () in the output signal spectrum.

The dependences of the suppression of these harmonics on the phase errors of the corresponding bits have an almost identical character, for example, an error in the discharge for 4–1 ° provides the third harmonic level of 43.4 dB; 2 ° - 37.3 dB, the error in the discharge D / 2-1 ° -44.1 dB; 2 ° -38.1 dB, etc.

Thus, for convenience of computations, one graduation curve of the dependence of & p on the level of the corresponding harmonics can be constructed, or the same scale can be used, increasing the measurement error by only 0.15 degrees, which is much more accurate than in the known methods. The error of extrapolated points, for example, 39 dB - 1.5 °, also fits into these values.

Evaluation of phase errors of the phase shifter can be done with the simultaneous operation of all bits as the phase

modulation in each cell affects only its own harmonic series and does not affect others. This makes it possible to eliminate from the measurements numerous switching cells and reduce the measurement time by more than 2P times, where n is the number of discretes of the phase shifter.

FIG. 1 shows block diagrams of a device for measuring phase characteristics by the phase ring method (a) and short circuit (b); Fig. 2 shows a typical output spectrum of a discrete binary n-bit phase shifter, the control inputs of which are supplied with sequences of meanders Q in Fig. 3 — the averaged dependence of the phase error of bits n n / 2; /four; /eight; tg / 16 from harmonic levels with n 0; ± 1; ± 3; ± 7; ± 15 respectively; 4 is a block diagram of a device for measuring phase errors of a discrete phase shifter according to the proposed method.

In Fig.1 marked 1 - microwave generator; 2. 6, 7 - valves; 3 - power source; 4 - phase shifter; 5, 8 - attenuator; 9 - radio line; 10 power amplifier.

Figure 4 indicated: 1 - microwave generator; 2 - spectrum analyzer; 3 - control signal generator; 4 - discrete phase shifter.

Example. The implementation of the proposed method using the flowchart shown in figure 4.

The output microwave signal from the generator 1 is fed to the microwave input of the discrete phase shifter 4. The control inputs of the phase shifter 4 from the generator outputs 3 of the control signals are transmitted to the sequence of the meanders: to the input of the Atg- sample with frequency C, to the input of Atg / 2 with frequency 2Q, to the input A / 4 - with a frequency of 4Q, to the input A / 8 - with a frequency of 80o and to the input Dtg / 16 - with a frequency of 1bOe.

As a result of the phase modulation occurring at the frequencies listed above, the microwave signal forms a discrete spectrum at the output, a typical view of which is shown in FIG. 2. Using the spectrum analyzer 2, discrete components are measured in the output spectrum.

In the case of synchronization of the control pulses by a decrease in the values of the harmonics with n Q, I, -3, -7, -I5, in accordance with the dependence given on FMG 2, they conclude that the phase errors of the bits of Aj; Atg / 2; & rt / 4; Atu / 8; Agat / 16, respectively, in the case of synchronization

along the front, a similar conclusion is made in value with n 0.1, e, 7, 15.

The feasibility of the proposed method for measuring phase errors is to increase the accuracy of measuring phase errors less than 1 °, s reducing the time measurement phase errors more than 2P times, reducing the size of the workplace, simultaneously indicating all phase errors, which allows not only increase the measurement speed, but also significantly simplify the adjustment of phase shifters due to the ability to easily determine the combination errors resulting from the interaction of individual bits on the reflected th waves

The proposed method has no restrictions on the power level of the input signal, which increases the reliability (accuracy) of measurements of the phase characteristics of phase shifters used in VUM.

Claims (1)

Invention Formula A method for measuring the input phase errors of a discrete binary phase shifter, based on applying a microwave signal to its input, and on controlling inputs of control voltages, in order to reduce the time measurements and achieving the possibility of measurements at a high power level; rectangular voltages with a duty cycle of 2, synchronized along the front, are used as control voltages. or decay, the period of which with the increase in the digit number of the multi-bit binary phase shifter decreases by 2 times, measure the amplitudes of the spectral components of the output the signals that determine the introduced phase errors, while the optimal period of the control voltage applied to the first discharge of a multi-bit binary phase shifter, is chosen at least 50 times the sum of the front and fall times, and the phase error introduced by n -th bit, determined by the amplitude of the () -th harmonic output spectrum 1 6) si w ti zi IT from b in g e s "i Ј g t o - g - g-b-s-9-g- & - b-ov-n-zt-ft -" - si680 l Phie