RU2225988C2 - Phase-meter - Google Patents

Abstract

FIELD: measurement complexes designed to measure fields of antennas. SUBSTANCE: phase-meter is intended for utilization in radio navigation, radiolocation and radio control equipment. It has 0-90 deg phase inverter across first input to which reference signal is fed, 0-180 deg phase inverter connected to its output, adder, detector, analog-to-digital converter and computer connected in series, control unit connected with outputs to control inputs of 0-90 deg phase inverter and of 0-180 deg phase inverter, attenuator which input is second input of phase-meter to which measured signal is fed, its control input being connected to output of control unit and its output being connected to first input of adder. Amplifier-limiter incorporated in phase-meter is placed between output of 0-180 deg phase inverter and second input of adder. First output of computer is connected to input of control unit and its second output is output of phase-meter. EFFECT: increased measurement accuracy thanks to diminished influence of phase inverters on amplitude of reference signal, expanded functional potential and application field of phase-meter 1 dwg .

Description

The invention relates to measuring technique and can be used and measuring systems designed to measure the field of antennas and headlamps. as well as in navigation, radar and radio control devices.

A known phase meter containing at each of two inputs an attenuator connected through an amplitude detector to the input of a differential amplifier. The output of the amplifier is connected to the control input of the first attenuator and through an inverter to the control input of the second attenuator. The output of each attenuator is also connected to the inputs of two shapers of the sum, the difference, the outputs of which through the detectors are connected to the first and second inputs of the calculator, the third input of which is connected to the output of the control unit, and the fourth and fifth are connected to the inputs of the amplifier (ed. USSR certificate No. 890266 , G 01 R 25/00).

However, the known device has insufficient functionality, in particular, it does not allow to measure the amplitude of the signal.

The closest known to the proposed one is a phase meter containing 0–90 ° phase shifter at one input, 0–180 ° phase shifter at the other, connected to the control output of the control unit by other inputs, and outputs connected to the inputs of the sum unit connected through the envelope detector to a switch, the other input of which is connected to the control output of the control unit, and the outputs connected to the inputs of four voltage memory blocks connected to the inputs of the functional converter, the output of which is tsya output phase meter (application No. 93018597, G 01 R 25/04).

However, this phasemeter has insufficient measurement accuracy due to a change in amplitude when switching phase shifters, as well as limited functionality, because it does not allow measuring the amplitude values of the signal.

The aim of the invention is to improve the accuracy and expansion of the functionality of the phase meter.

This goal is achieved by the fact that in the phase meter, containing at the first input a phase shifter 0-90 °, to which a reference signal is supplied, a phase shifter 0-180 ° connected to its output, series block connected in series, detector, analog-to-digital converter and calculator, block control outputs connected to the control inputs of the phase shifter 0-90 ° and phase shifter 0-180 °, an attenuator is introduced, the input of which is the second input of the phase meter, to which the measured signal is fed, the control input of which is connected to the output of the unit control, and the output is connected to the first input of the sum unit, and the amplifier-limiter connected between the output of the phase shifter 0-180 ° and the second input of the sum unit, the first output is connected to the input of the control unit, and the second output is the output of the phase meter.

In the proposed device, elements traditional for such circuits are used: discrete phase shifters, sum unit, analog-to-digital converter, calculator, attenuator. However, due to the introduction of an attenuator and an amplifier-limiter and, in general, a circuit solution that implements the necessary algorithm, which involves the attenuator locking the input of the phase meter, measuring the closed second input of the reference signal and taking into account its difference in measurements, it is possible to achieve:

- improving the measurement accuracy by reducing the influence of phase shifters on the amplitude of the reference signal;

- measuring also the amplitude characteristics of the devices.

The invention is illustrated in the drawing, which shows a block diagram of the proposed phase meter.

The phasometer contains a serially connected input phase shifter 1 0-90 °, a phase shifter 2 0-180 ° and an amplifier-limiter 3, connected to one of the inputs of the sum unit 4 with an output, an attenuator 5 connected to the other input, the input of which is the second input of the phase meter. The output of the sum 4 block is connected through a series-connected quadratic detector 6 and analog-to-digital converter 7 to the input of the calculator 8, the outputs are connected to the control unit 9, the outputs of which are connected to the control inputs of the phase shifters 1, 2 and attenuator 5, while the other output of the calculator 8 is phase meter output.

The phasometer works as follows.

The reference signal from an external generator is fed to the first input of the phasemeter. The measured signal is fed to the second input of the phasemeter. The input signal of the sum 4 block receives the reference signal through an amplifier-limiter 3, which almost completely eliminates the change in its amplitude when switching the phase shifters 1.2. However, due to the imperfect operation of the amplifier-limiter 3, there remains a certain change in the amplitude, which reduces the measurement accuracy, therefore, the measurement mode is preceded by a calibration mode. Why, the calculator 8 provides a signal to the control unit 9, which closes the second input of the phase meter with an attenuator 5. Then, also by the signals from the calculator 8, the control unit 9 switches the phase shifters 1, 2, and the calculator 8 remembers the four signal values. Such a measurement of the signal amplitude when the second input of the phase meter is closed is fundamental in increasing the accuracy. These four values are used to indicate the input power level of the reference signal, as well as to take into account their difference in subsequent measurements by recalculating the values by the formulas

where i = 2 ... 4. moreover, i = 1 corresponds to the state when the phase shifters 1 and 2 are turned off, that is, they are in a state of zero phase shift.

Further, in the measurement mode, instead of the measured values of U ₁ ... U _4, it is necessary to use the values Y ₁ ... Y ₄ corresponding to these states of the phase shifters 1 and 2. wherein Y ₁ = U ₁ .

The measurement is as follows.

The reference and measured signals are respectively supplied to the first and second inputs of the phase meter. The measurement cycle consists of four measures.

In the first cycle, the control unit 9 opens the attenuator 5, passing the signal to the input of the sum 4 block, and sets the phase shifters 1, 2 to the state of zero phase shift. The measured signal value is recorded in the ADC 7 and stored by the calculator 8.

In the second cycle, the phase shifter 2 is set by the control unit 9 and the state of 180-degree shift, the received signal value Y ₂ is fixed to the ADC 7 and the difference Z ₁ = Y ₁ -Y _{2 is} determined in the calculator 8.

In the third cycle, the phase shifter 2 by the control unit 9 returns to the zero phase shift state, and the phase shifter 1 is set to the 90 degree shift state. ADC 7 captures the value of the signal Y ₃ .

In the fourth cycle, the phase shifter 2 switches to the 180-degree phase shift state and the signal value Y ₄ is fixed, and the difference Z ₂ = Y ₃ -Y _{4 is} calculated by the calculator 8. The calculation of the differences Z ₁ , Z ₂ is also an essential feature of this scheme, aimed at automation and improving the accuracy of measurements.

Since the measured values of the signal at the output of the quadratic detector 6 can be described by the expressions:

Y ₁ = K $\genfrac{}{}{0ex}{}{\text{2}}{\text{0}}$ + E $\genfrac{}{}{0ex}{}{\text{2}}{\text{u}}$ + 2Е _о Е _u · cosφ _x ),

Y ₂ = K $\genfrac{}{}{0ex}{}{\text{2}}{\text{0}}$ + E $\genfrac{}{}{0ex}{}{\text{2}}{\text{u}}$ + 2E _o E _u cosph _x ),

where K is the conversion coefficient of the detector, E _o is the amplitude of the reference signal at the input of the detector, E _u is the amplitude of the signal from the measured device at the input of the detector, φ _x is the measured phase shift, and K and E _o after calibration are constant.

Hence the difference in measured values are equal

Z ₁ = 4KE _o E _u cosφ _x ,

similarly

Z ₂ = 4KE _o E _u sinφ _x .

According to the obtained values, the calculator 8 finds the amplitude and phase shift:

Having determined the amplitude-phase components of the signal using the formulas, the calculator displays them on an indicator or in an external communication channel for use in automated measurement procedures.

Thus, the proposed phase meter provides a measurement of the amplitude-phase characteristics of the devices, while improving the accuracy of measurements by significantly reducing the influence of phase shifters on the amplitude of the reference signal. Using the proposed solution can significantly expand the functionality and scope of the meter.

Claims (1)

A phasometer containing a 0-90 ° phase shifter at the first input, to which a reference signal is supplied, a 0-180 ° phase shifter connected to its output, series unit, detector, analog-to-digital converter and calculator, control unit, outputs connected to control inputs phase shifter 0-90 ° and phase shifter 0-180 °, characterized in that an attenuator is introduced into it, the input of which is the second input of the phase meter, to which a measured signal is supplied, the control input of which is connected to the output of the control unit, and the output is connected to the first input of the sum block, and the amplifier-limiter is connected between the output of the phase shifter 0-180 ° and the second input of the sum block, while the first output of the calculator is connected to the input of the control unit, and the second output is the output of the phase meter.

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