RU1772764C - Method of determining phase shift of phase-shift keyed signal - Google Patents

Abstract

Usage: in the field of radio measurements, namely in phase metering, as well as in the communication and radar technique where phase-shift signals are widely used. Summary of the invention: the method reduces the time of phase shift measurement and implements a phase-shift signal with a known carrier frequency at the input of the spectrum analyzer, consisting of consisting of two subpulses of the same duration r, fixing the position of the frequency Fminj corresponding to the minimum of the spectral envelope closest to the carrier frequency, and the frequency Ptnn corresponding to leading from the carrier to the minimum envelope of the spectrum, measuring the frequency interval from Fmirn and determining the magnitude of the phase shift according to the formula A0 2NG (-Fminl) - - JlSCj (F mln - F mini). 3 IL. sl c

Description

The invention relates to the field of radio measurements, namely phasemetry, and can be used in communication and radar techniques where phase-shifted (FM) signals are widely used.

A known method for determining the phase shift in the FM signal by the spectral method is 1 Moleben V B Some questions of measuring fast phase changes. - In the book: Automatic control and methods of electrical measurements (proceedings of the 5th conference). - Novosibirsk, Publishing House of Science SB of the USSR Academy of Sciences, 1965, p. 87-93, based on the use of spectral analysis of a periodic FM signal, consisting of two subpulses of the same duration, in which the magnitude (amplitude) of the carrier oscillation C is measured using a spectrum analyzer. normalizes it to the magnitude of the carrier oscillation of the unmanipulated

signal Uo and determine the phase shift value by the formula;

Av 2agssoz (iuui0).

0)

The dependence of the magnitude of the carrier wave on the magnitude of the phase shift is presented in 1 s. 91 images 51. At Д0 180 °, the carrier oscillation in the spectrum of the FM signal disappears, at Д0 0 ° its value is maximum and equal to Do.

The disadvantage of this method is the long measurement time, due to its two-stage (after measuring the value of eggs, it is necessary to make switches to remove the manipulation and only after that the value of Do is measured). In addition, the method is characterized by low accuracy, which is associated with the use of amplitude measurements.

h

3

vj

ABOUT

The closest technical solution, selected as a prototype, is a method for determining the phase shift in the FM signal. Seleva M.R., Gimadeeea L.A. Peysakhov L.A. Pichugin A.Yu. Raskin V.K. A method for determining phase shift in a phase-shifted signal. A positive decision dated November 25, 88, by application No. 4442128 / 24-21, based on the use of spectral analysis of the studied periodic FM signal a with a known carrier frequency Fo, consisting of two subpulses of the same length t. During the analysis, the position of the frequency Fmin corresponding to the minimum spectral envelope closest to the carrier frequency is fixed on the analyzer screen. Then, the spectrum of a harmonic signal whose frequency is equal to the carrier frequency of the FM signal F0 is analyzed, the frequency interval between the fixed frequency Fmin and the frequency FO is measured, and the phase shift value is determined from the measured frequency difference by the formula:

DE -2r (Fmmi-Fo), (2)

where FO is the carrier frequency.

d is the duration of the subpulse. The disadvantage of this method is the long measurement time due to its two-stage operation (after fixing the position of the frequency Fmin, it is necessary to switch to remove the manipulation and establish the mode of continuous generation of the harmonic signal, and only after that the value is measured (Fmin-F0) As can be seen from Appendix 1, in the method for determining the phase shift adopted for the prototype, operations No. 3 .... 4 (associated with switching the type of work) double the total quantitative operations during the measurement. increases the measurement time is 2.5 - 3 times.

An object of the invention is to reduce the time for determining phase shift. This goal is achieved by the fact that in the 8th known method for determining the phase shift in the FM signal, based on the use of spectral analysis of a periodic FM signal U (t), consisting of two subpulses of the same duration t, at which the value of the frequency Fmin is fixed during analysis corresponding to the minimum of the spectral envelope closest to the carrier frequency, additionally fix the value of the frequency Fmin corresponding to the minimum of the spectral envelope next to the carrier frequency, measure

the frequency range from Fmin to Fmin and the measured phase difference determines the magnitude of the phase shift according to the formula:

D0 2NG (P tnlna - F mm 1) - TTSgn (F min2 F mini)

(3)

This expression is obtained as follows. In the materials of the application No.

4442128 / 24-21 from 05/12/08, adopted as a prototype, an analytical expression is obtained up to the spectrum envelope (S (w) / periodic phase-shift signal U (t) with a carrier frequency F0, consisting of two subpulses of the same duration g phase shift D ©. Considering the waveform close to ideal, i.e. practically no transients (E - 1) and parasitic amplitude modulus (t 1);

A, tl5in (W-W0U / 2 M

Ј Sint (Vf-W0 / S

 laotcoeHw-w.if + ieJ

(i)

25

First factor

A 1 t

sets mas

eat

spectrum envelope headquarters.

The second multiplies | sin (W-W0) fsln (W-Wo) the zeniths of the spectrum envelope independent of zeros (minima) Fmin2i:

determines half a lg (F min2i F о) Y / 2 + i l, whence 35 F F о + IA, (5)

where (1 1,2,3., ..)

factor

T re t and and -.- ....

For 2 (1 + cos (W-W0) r + Д0, the position of the spectral envelope dependent on zeros (minima) F minik is determined:

2 l: (F mimk -Po) r + D @ l: + (k-0,1,2,3 ...) (6)

The position of the minimum closest to the carrier frequency Pt | n {With respect to F0, is used in the method adopted for the prototype to determine the phase shift:

 -2r (Fmim -Fo) (7)

In the claimed method, the phase shift is determined by the relative position of the minimum of the spectral envelope Fmini closest to FO and the next minimum (whose position is independent of DE Fmin2

Let us consider separately the cases Two 0; l: 3 and D0e - tg; 0

1. When

F m i u FO and the position of the next minimum is determined from (4) as FminZ - F0 + 1 / g (with Fmin2 -Fo 0)

From where Fo Fmin2-1 / g. Substituting this value of Fo in (7), we obtain

Д0 Я 1 -2Г (РГ | П1 -Fminj) - (РтШ2 -Fmlnl) Л (8)

2. At -l; 0 Fmini Fo and the position of the next minimum we define from (4) as Fmtna 1 G (with THIS Fmin2-Fmin1 0)

where from

F0 Fmln2 + 1 / tr.

Substituting this value F0 in (4) we obtain

(r.p., -R.p.pa) +2 -Wfr (Fm-, na-Fni..2W (Finjflft-FWi

- (Sa)

Using the sgn (x) function {see 6. Korn G., Korn T., Handbook of mathematics. For scientists and engineers, trans. from the English Ed., Aramanovich I.G., ed. 2, Science M., 1970, p. 677. You can combine formulas (5) and (5a)

Д © 2 ЯГ (Р mln2 F mini) - ТС sgn (F т (п2 F mint).

Note:

-1 if x O sgn (x) J 0x 0

1

x 0

The proposed method differs from the known technical solutions in that it uses a new sequence of operations (which does not require switching the type of operation of the generator) and therefore meets the criterion of novelty, and also meets the criterion of significant differences, because A new feature is proposed - the determination of the phase shift in the FM signal using the relationship between D0 and the frequency interval Fmin2-Fmini in its spectrum. This feature has not only not been used previously to determine phase shift, but has not been quantified.

In FIG. 1 is a block diagram of a device implementing the proposed method, and FIG. 2 - dependence of the frequency interval Fmin2-Fmini AF on the phase shift D0.

In FIG. For represented a periodic FM signal U (t), and in FIG. 3 b - spectrum of this

signal near the carrier frequency F0.

The device consists of a microwave oscillator 1 connected through a phase manipulator 2 to the input of a spectrum analyzer 3, as well as a series-connected pulse generator 4, a time delay unit 5 and a pulse generator 6, and the output of a pulse generator 4 is connected simultaneously to the input of an external pulse modulation generator of microwave oscillations 1, and the output of the pulse generator 6 to the control input of the phase manipulator 2.

In FIG. 1, the block and power circuits are not shown. Measurement by the proposed method using the device is carried out as follows.

Turn on the axis blocks of the device. In the microwave oscillation generator 1, an external pulse modulation mode is set using a type of operation switch. The pulse generator 4 generates periodically repeating pulses with a period T and a duration of 2 tons, which are fed to the input of an external pulse modulation of the microwave oscillator 1, and through the time delay unit 5, with a delay time

t, to start the pulse generator 6. In this case, the microwave oscillator generates radio pulses with a carrier frequency F0 of 2 t duration and a repetition period T. Pulse generator 6 upon receipt

generates video pulses of duration r to its input of triggering pulses, which are fed to the control input of the phase manipulator 2, at the time of the arrival of video pulses to the control input,

phase manipulator 2 abruptly changes the phase of the high-frequency oscillation in the radio pulse by a value of D0. Since, thanks to the presence of a block of time delay 5, the pulses at the control input

phase manipulator 2 appears with a delay of t relative to the leading edge of the radio pulse, the duration of the last is equal to 2 t, then an abrupt change in phase occurs in the middle

radio pulse. Thus, at the output of the phase manipulator 2, a periodic phase-shifted signal U (t) is generated (Fig. 3a) with a carrier frequency Fo, consisting of two subpulses of the same duration r with a phase shift D0, the value of which must be measured.

On the screen of the spectrum analyzer 3, an image of the FM signal spectrum consisting of a set of lines is observed (Fig. 36). The envelope of these lines corresponds to the envelope of the signal spectrum, and the spectrum itself will be close to solid. The process of obtaining the image of the spectrum is described in more detail in 3. Mirsky G.Ya. Electronic measurements. 4th ed., Rev. and add. M: Radio and communications, 1986, p. 232. The positions of the frequency Fmini corresponding to the minimum of the spectral envelope closest to the carrier frequency are fixed, and the frequency Fmin2 corresponding to the minimum of the spectral envelope next to the carrier frequency. One of the methods, depending on the particular type of spectrum analyzer, for example, using the built-in frequency meter and digital indicator, measures the frequency interval between Fmin2 and Fmini and determines the phase shift using the formula:

A0 (Fmin2 -F mlm) - L Sgn (F mln2 F mini).

The relationship is shown in FIG. 2.

Thus, in the proposed method for determining the phase shift in the phase-shifted signal in comparison with the prototype, the need for switching the type of operation of the operation generator NN 3 ... 4 of the table is eliminated. P1). This reduces the measurement time by 2.5-3 times (see Appendix 1).

As block 1 can be used, for example, a high-frequency generator G4-107 4. Radio measuring instruments. 1981 Catalog prospectus. The central branch body of scientific and technical information ECOS. - M.: 1981, p. 234. Block 2 can be performed, for example, according to the scheme of Fig. 6. 16 5. Sokolinsky 8. G. .. Sheinman V. G. Frequency and phase modulators and manipulators. - M .: Radio and communications, 1983. p. 192, ill. Serial instruments can be used as a spectrum analyzer, for example, C4-27 and C4 74 74 s. 140. Blocks 4. 6 - pulse generators, and a - example G5 - 54 4. s. 209. The time delay block 5 can be structurally combined with block b, for example, as in the generator G5-54.

Claims (1)

SUMMARY OF THE INVENTION A method for determining a phase shift in a phase-shifted signal based on using spectral analysis of a periodic phase-manipulated signal with a carrier frequency of two, consisting of two subpulses of the same duration m, during which the value of the frequency Fmin corresponding to the first minimum of the spectral envelope closest to the carrier frequency is distinguished during the analysis, characterized in that, in order to reduce time required to determine the phase shift, during the analysis, the first minimum is determined by its location between the two largest maximums of the spectral envelope, and also fix the value frequency Fmin2 corresponding to the second minimum of the spectral envelope following from the carrier frequency, the frequency difference between the second first minima of the spectral envelope is determined, and the phase shift value D © is determined from the obtained frequency difference taking into account the sign of this difference: 35 A0 2yyy (Ptt2 -Fmln1) - - To sgn (F mjn2 - F mini), where r is the duration of the subpulses, Fmini is the frequency of the first minimum of the spectral envelope; Fmin2 is the frequency of the second (neighboring) minimum of the spectral envelope; sgn is the operation of accounting for the sign of the frequency difference. Ј 3 " to p t IS W I Fming Fmins -fmini FIG. 36