SU1448299A1 - Method of measuring accompanying phase modulation in lines with amplitude-modulated signals - Google Patents

Abstract

The invention can be used to measure the associated phase modulation in precision oscillators and sources of amplitude modulated signals, to measure the associated phase modulation introduced by various nodes and transmission paths of amplitude modulated signals. The purpose of the invention is to increase the resolution and accuracy of measuring small values of the accompanying phase modulation (FM) with large values of the amplitude modulation coefficient (Alt) - achieved by using the second side frequency components (Co0 +, Qj, - 2P.) AM spectrum and compensation of AM components (second harmonics of the envelope) at these frequencies using an adjustable non-linear functional converter .3. This eliminates the influence of the AI components on the resolution and accuracy of the measurement of the accompanying FM. In addition, an increase in accuracy is achieved due to an accurate measurement of M at your output of the FM modulator 5 with AM turned off at the AM signal source using a deviometer, i.e. the error is eliminated due to AM - (M-conversion. According to the measurement method, a sinusoidal signal V-V cos cot from the output of the generator 1 of modulating voltage is passed through a non-linear functional converter 3, you output -. The input signal of which is U, 2IU cos (irt ) t Ui is fed to the modulating input of the AH generator 4. The amplitude and phase characteristics of the nonlinear functional converter 3 are compensated for by the components of the second harmonic of the AM signal envelope. The compensation is controlled by analyzer 6 of the spectrum. but, in order to receive full compensation, they are compensated, these (с s: 00 Yu with so

Description

1448299

the harmonics using the attenuator 8 and the output of the phase modulator b are measured by the phase shifter 9 in the phase modulator and the index of the accompanying phase power is 5. Then the amplitude modulation in the LM modulator 7 is turned off with the key 2 and at 3 il.

one

The invention relates to a radio metering technique and can be used when measuring the accompanying phase modulation in precision generators and sources of amplitude modulated signals, when measuring the accompanying phase modulation introduced by various nodes and transmission paths of amplitude modulated signals.

The purpose of the invention is to increase the resolution and accuracy of measuring small values of the accompanying phase modulation with large values of amplitude modulation coefficients.

Improving the accuracy and resolution of measuring small values of the accompanying phase modulation is achieved by using the second side frequency components ((LOo + 2Я and co-2S2) of the amplitude-modulated signal and compensation components to compensate for phase modulation. amplitude modulation (second harmonics of the envelope) at these frequencies using an adjustable nonlinear functional converter. This eliminates the influence of the amplitude modulation components on the resolution and accuracy of Eren accompanying phase modulation.

In addition, higher accuracy is achieved due to the possibility of accurate measurement of phase modulation at the output of the phase modulator with the amplitude modulation turned off at the source of the amplitude-modulated signal using a deviometer, i.e. elimination of errors due to AM - W-transform.

FIG. 1 and 2 are diagrams for the implementation of the method; in fig. 3 shows an embodiment of an adjustable non-linear functional converter.

A device for measuring phase modulation and amplitude-modulated oscillators contains a series-connected modulating voltage generator 1, a switch 2, an adjustable non-linear functional converter 3, a tested AM generator 4, a phase modulator 5 and a spectrum analyzer 6, as well as a 7 deviation meter frequencies and serially connected attenuator 8 and phase shifter 9, the output of which is connected to the second input of the phase modulator 5,

A device (Fig. 2) for measuring the associated phase modulation in nonlinear quadripoles contains a series-connected modulating voltage generator 10, a switch, an adjustable nonlinear functional converter 12, A AM-genator 13, first phase modulator 14, tested quadrupole 15, second phase modulator 16, switch 17 and spectrum analyzer 18, to the input of which the meter 19 frequency deviations are connected, as well as the first and second attenuators 20 and 21, the first and second phase shifters 22 and 23, the second The switch 11 is output through a serially connected first attenuator 20 and a perforator phase shifter 22 connected to the second input of the first phase modulator 14, and an output of the generator 10 via a serially connected second attribute: the numer 21 and the second phase shifter 23 connected to the second input of the second phase modulator 16.

Adjustable nonlinear functional Converter (Fig, 3) contains a serially connected attenuator 24, frequency doubler 25, second attenuator 26 and adder 27,

31448299

whose second input is input 4-0 °

converter ..Uj

The method of measuring the associated phase modulation in amplitude modulated signals is performed as follows.

A sinusoidal (harmonic) signal from the generator of the modulating voltage U, U coscOt is passed through a nonlinear functional converter. The signal is distorted, harmonics of the modulation frequency and

oo

and. cos () t.

number

where i 1 2, 3,.,

modulation frequency.

The signal (1) is fed to the input of the AM generator.

At the output of the generator, tea, a high amplitude modulated carrier frequency of the coV is formed with the required amplitude modulating phase modulus

-t-tsotg

 + 21 t, -cos (i-S2) t 21l "(() cosl () t +4;, i (- n.-oo -

and

U cosQot + I

+ ci) t + 2J- cos (c;) o “) t +

+ I cos (Wo + n) t -btf, - - I cos (c:) o-5) t -Cf. +

Cos (+

where m; - fractional amplitude modulation coefficient for i-harmonics;

5 — index of concomitant phase modulation;

1, (p) are the coefficients that are Bessel functions of the first kind of various orders (n 1, 2, 3 ...) of the argument | 5 I

wed; - phase shift between the envelope of the amplitude-modulated signal along the i-th harmonic and the modulating function of the accompanying phase modulation. Since in quality AM-generators the value of the index of concomitant phase modulation is usually small () when decomposing (2) into sinusoidal components in Bessel functions, components of a higher order than unity can be neglected. In addition, for simplicity, consider the case of only the second harmonic (i 2) in the envelope amplitude modulation. With this in mind, from (2) we obtain

t,

COS (“0+ 2Q) t + COS (“ o-2Q) t +

and. cos () t.

(one)

harmonic number

where i 1 2, 3,.,

modulation frequency.

The signal (1) is fed to the modulating input of the AM generator.

At the output of the generator, in general, a high-frequency amplitude-modulated signal at the carrier frequency of cov is formed with a distorted amplitude modulation law and concomitant phase modulation.

(2)

21 cos (coO + 2a) t

+ Cfjm

four

cos g (MO- 2Q) t -Cfilj, (3)

It can be seen from (3) that the amplitude modulated signal with accompanying phase modulation simultaneously with the components of the second harmonics of the amplitude modulation envelope (the sixth and seventh terms in curly brackets) contains the components of the associated phase modulation (eighth and ninth terms) with the same frequencies (COO 2flj, Qp-2I) phase shift Cf and amplitudes

mi

Analyzed X. GI D (/

The spectrum torus indicates the resultant amplitude (and 4.1 and 1) of the lateral components at the OE + 2Q frequencies. and od-2 $ 2

Um 2

   + m, mjj3co8q,

V,

and

-2

Urn

2

J m - m, inj D coscf, +

 ; -.

w

In the proposed measurement method, the amplitude and phase characteristics of the nonlinear functional converter are compensated by compensating for the components of the second harmonic of the envelope in the amplitude modulated signal, which corresponds to case O for formulas (3) and (D).

Under this condition, it follows from (4) that the amplitudes U. and U reach a minimum and are equal to

and

and, t

t, /

tj 4

Further, using the phase modulator, the signal (3) with the compensated harmonics of the distortions of the envelope of the amplitude nozzle is added to the signal (14482996)

concomitant phase modulation in (5) prototype), which is 3-5% for better spectrum analyzers. This corresponds to 0.03-0.5 glad.

Uh

Thus, the proposed measurement method allows a two-fold increase in the resolution of the measurement of the associated phase modulus.

Thus, the proposed measurement method allows a two-fold increase in the resolution of the measurement of the associated phase modulus.

positive phase modulation with Q-modulation at amplitude modulated by a sig- nal frequency {2 .nals.

By adjusting the amplitude and phase of the device (Fig. 1), which implements the Duplicating voltage supplied by the Phase Modulator, the compressed method is obtained, the measurement of the accompanying phase modulation in the AM generators of the spectrum of the spectrum is performed as follows: zero This will take place when additional phase modulation with

zom.

-index 5 will be equal to (b a

/ phase shift additional and concomitant

, about

thirty

The sinusoidal signal from generator 1 through switch 2 is fed to an adjustable nonlinear function of phase modulation equal to 180. The Q converter is 13. Modulated After that, the amplitude modulation signal in block 3 is distorted (1) in the AM generator is turned off. At the output of the phase modulator, there will be a phase-modulated signal with an index / attendant phase modulation. The value is the input of the AM generator 4. The output of the index at the output of the phase modulator of the checked AM generator 4 is measured by any known method, for example, by means of frequency detection using a frequency deviation meter. At the same time, amplitude modulation due to the LM-FM transform will not distort the measurement result of the accompanying phase modulation.

Suppose there is a spectrum analyzer with a dynamic range of D -80 dB. It is required to measure the contiguous phase modulation in the amplitude-modulated signal at M 100%. If the components and frequencies (3, 2S2 and C, - 2Q are compensated for with respect to the amplitude of the carrier U to a level equal to the value of the dynamic range. Spectrum analyzer D. - 0.0001 (minus.

80 dB), then the resolution of the lateral components of the spectrum, caused by the measurement of the accompanying phase moduli, due to its own distortions of the bend, harmonics of the modulation frequency appear in it.

This signal is applied on the modulating case, a high-frequency amplitude-modulated signal is generated (2) with a distorted amplitude modulation law and concomitant phase modulation. In this case, the distortions of the amplitude modulation envelope are caused both by the introduction of a distorted modulating signal from converter 3 and by the own nonlinear distortions of the envelope of the AM oscillator. The signal (2) passes through the phase modulator 5, where additional phase modulation is introduced into it and fed to the input of the analyzer 6 of the spectrum i

Using an adjustable non-linear functional converter 3 in an amplitude-modulated signal (3), the second is compensated to the minimum for the spectrum analyzer screen 6

40

If we take into account (5), it will be d, and the blood pressure will be 0.0004 rad at 100% amplitude modulation.

In the prior art, the resolution of the measurement of the accompanying phase modulation is | 3wv, ft 0.25 / dB or 0.04 rad in terms of 100% amplitude modulation. It is due to the actual resolution of the amplitude measurement.

50

in the tested AM generator 4. Next, the attenuator 8 and the phase shifter 9 compensate the second side spectral components to zero. Using switch 2, turn off the amplitude modulation in the generator being tested with a deviation meter, and measure the phase modulation at the output of phase modulator 5, which is numerically equal to the accompanying phase modulation in the tested one. AM generator.

and

4-1

   yi (compensation point

associated phase modulation in the prototype), which is 3-5% for the best spectrum analyzers. This corresponds to 0.03-0.5 glad.

Thus, the proposed measurement method allows a two-fold increase in the resolution of the measurement of the associated phase modulus.

in amplitude modulated signals.

 in the device (Fig. 1), which implements

The proposed method, the measurement of concomitant phase modulation in AM-genesis.

The signal in block 3 is distorted (1) is the input of the AM generator 4. At the output of the checked AM generator 4, in

and harmonic modulation frequencies appear in it.

This signal is applied to the modulator.

 The signal in block 3 is distorted (1) the 25th input of the AM generator 4. At the output of the checked AM generator 4, in

  .

 The lateral components of the spectrum, caused by the intrinsic distortion of the envelope, form a high-frequency amplitude-modulated signal (2) with a distorted law of amplitude modulation and concomitant phase modulation. In this case, the distortions of the amplitude modulation envelope are caused both by the introduction of a distorted modulating signal from converter 3 and by the own nonlinear distortions of the envelope of the AM oscillator. The signal (2) passes through the phase modulator 5, where additional phase modulation is introduced into it and fed to the input of the analyzer 6 of the spectrum i

Using an adjustable non-linear functional converter 3 in an amplitude-modulated signal (3), the second is compensated to the minimum for the spectrum analyzer screen 6

40

 lateral components of the spectrum caused by their own distortions around

in the tested AM generator 4. Next, the attenuator 8 and the phase shifter 9 compensate the second side spectral components to zero. Using switch 2, turn off the amplitude modulation in the generator being tested with a deviation meter, and measure the phase modulation at the output of phase modulator 5, which is numerically equal to the accompanying phase modulation in the tested one. AM generator.

In the device (FIG. 2), the measurement of the accompanying phase modulation in nonlinear quadrupoles is carried out as follows.

The modulating signal from the generator 10 through the switch 11 and the adjustable non-linear functional converter 12 is fed to the modulating input of the AM generator 13.

At its output, a high-frequency signal (2) is formed with a distorted law of amplitude modulation and concomitant phase modulation. With the help of phase modulator 14, an additional phase modulation is introduced into the amplifier 15 of the generator and receives a time-modulated signal (2). The spectrum analyzer 18 is initially connected to the output of the phase modulator 14. Using an adjustable nonlinear functional converter 12, an attenuator 20 and a phase shifter 22 in a signal of the form (3) at the output of the phase modulator 14, the second side spectrum components caused by its own distortions of the envelope and accompanying phase modulation in the AM generator 13.

Thus, an amplitude-modulated signal without distortion of the second harmonic of the envelope and without accompanying phase modulation is fed to the input of the checked quadrupole 15. The nonlinear quadrupole 15, in the general case, again introduces nonlinear distortion and the associated phase modulation into the amplitude-modulated signal. Spectrum analyzer 18 and frequency deviation meter 19 are connected by switch 17 to the output of phase modulator 16.

Using a non-linear functional adjustable transducer

but through the phase shifter 24 to the doubler 25 frequency input. At the output of the frequency doubler 25, a second harmonic of the modulation frequency is formed, through the attenuator 26 to the second input of the signal mapper 27. Thus, at the output of the signal adder 27, a modulating signal is generated with the second harmonic of the modulation frequency. The amplitude and phase of the second harmonic is controlled by the attenuator 26 and the phase shifter 24. Turning on the phase shifter 24 to frequency doubler 25 simplifies the practical implementation of the converter, since the phase shifter may have half the phase shift adjustment limits.

Claims (1)

35 claims The method of measuring the accompanying phase modulation in the amplitude-modulus paths in the annular signals, which consists in modulating the amplitude modulated oscillator signal by a low-frequency harmonic signal, the amplitude modulated signal is modulated by 12 in the amplitude-modulated signal-45 Phase, harmonic oscillation from the beginning on the screen of the spectrum analyzer 18 again compensates to a minimum the second lateral components of the spectrum. Now, the converter 12 compensates for both the envelope distortions arising in the AM generator 13 and the checked quadripole 15. Next, using an attenuator 21, the phase shifter 23 and the phase module of the current 16 in the amplitude-modulated signal at the output of the checked quadripole compensate for the accompanying phase modulus arising in the checked quadrupole. Turning off 50 55 the amplitude spectrum of the received signal, characterized in that, in order to improve the resolution and measurement accuracy for large values of the amplitude modulation factor, the modulating amplitude is preliminarily distorted the low-frequency harmonic signal, summing up its spectrum with a second harmonic with an adjustable amplitude and phase, suppresses to a minimum the second side co-ordinates. modulating voltage on the AM generator 13, using a deviation meter 19, the phase modulation at the output of the phase modulator 16 is measured, which is numerically equal to the phase modulation that occurs in the tested four-terminal 1 5. Adjustable nonlinear functional Converter (Fig. 3) works as follows. The modulating signal through the signal adder 27 passes the output through the phase shifter 24 to the input of the frequency doubler 25. At the output of the frequency doubler 25, a second harmonic of the modulation frequency is formed, which through the attenuator 26 is fed to the second input of the signal mapper 27. Thus, at the output of the signal adder 27, a modulating signal is generated with the second harmonic of the modulation frequency. The amplitude and phase of the second harmonic is controlled by an attenuator 26 and a phase shifter 24. Turning on the phase shifter 24 to frequency doubler 25 allows for a simpler implementation of the converter, since the phase shifter may have half the phase shift adjustment limits. Invention Formula The method of measuring the accompanying phase modulation in the amplitude-modulus paths in the annular signals, which consists in modulating the signal of the generator of amplitude-modulated oscillations by a low-frequency harmonic signal, the resulting amplitude-modulated signal is modulated by 0 five The amplitude spectrum of the received signal is analyzed in order to increase the resolution and measurement accuracy at large values of the amplitude modulation coefficient, and distort the low-frequency harmonic modulating in amplitude beforehand. the signal, summarizing its spectrum by a second harmonic with an adjustable amplitude and phase, suppresses the second side components of the amplitude spectrum to a minimum by adjusting in amplitude and phase parameters of the distorted amplitude modulating signal and phase modulating signal, and the index of the accompanying Phase modulation is measured by removing the modulating voltage from the amplitude modulated signal generator, and partial frequency detection and measurement is performed. FSH.2 Fig.Z