SU1580277A1 - Method of determining phases of electromagnetic pulses spaced in one channel in time - Google Patents

Abstract

The invention relates to phase metering and allows measurement of the phase difference in all frequency bands of electromagnetic oscillations, where a hane echo is observed, including in the optical range. For this, the measured pulses are simultaneously fed to two identical samples, in which a Khan's echo can be formed, the interval between them is measured. After time T is formed and the first reference impulse is fed to the samples. Then a second reference pulse is formed and fed to the first sample, the phase of which is equal to the phase of the first pulse, and the second reference pulse to the second sample, the phase of which is shifted @ / 2 relative to the first pulse. The maximum amplitudes of the Khan's echo from the first and second samples are then measured, and the phase difference is calculated using the formula given in the specification. 3 il.

Description

The invention relates to pulse phase metering and can be used to create phase meters to measure the phase difference between two pulse signals separated in time for all frequencies of electromagnetic oscillations, where a Han echo is observed, including RF, microwave and optical range,

The aim of the invention is to expand the frequency range.

On figa, b schematically depicts a sequence of pulses and Khan's echo: from the first and second samples; figure 2 - a sequence of pulses and Khanovsky echo from the second sample when determining the calibration amplitude AK (Ј); on fig.Z - scheme

device that implements the proposed method.

A sequence of pulses is applied to the first sample, first the first measured pulse Xf, then after the time Ј the second measured 1 pulse X and then through the time T -, 1 the first reference pulse P and then after the second reference pulse impulse P with zero phase shift relative to P c. Under the action of pulses in the sample, oscillatory processes are excited, which are manifested in the formation of bursts of radiation, called Hanov echo signals, i.e. after time b after the PZ pulse, two echo signals are simultaneously generated in the first sample — a two-pulse echo from the pulses P and P and a three-pulse e-stimulated echo from the pulses X ,, Xg and Pr. The effect of the formation of a composite echo that is a superposition of two echo signals is called phase effect, since the amplitude of the composite echo is a function of the phase difference (in the component signals. It is known that the amplitude

know the sum of (A1) 2 + (A1). To determine this value, a preliminary cycle of measurements was carried out on the second sample (Fig. 2). In the pulse train, instead of pulse X, the first sample pulse K (and, instead of X2, the second test pulse K, whose phase is equal to the phase of the pulse, then, after time T, serves the first reference pulse P., and after c; P, the third

A || A (O

dual pulse amplitude

echo;

stimulated amplitude

echo.

The resulting phase for the first sample is obtained

G, -lf (X,) - (f (X2) + q (P2) - 4f (P,), (2)

where C |) (X,) is the phase of the pulse Xj;

C (Hg) is the phase of the pulse X;

Cf (P,) is the phase of the pulse P ,;

TsKR2-) Phase of impulse Pit Since Cj (X2) q (X,) + (f, a C ((Pr) -Cf (Pf), (3)

then the square of the amplitude of the composite echo A. is a function of cos cp

one

(A1)

(A) 2

2A

cos u,

(four)

Similar oscillatory processes occur when a pulse sequence is applied in the second sample, with the only difference that instead of pulse P, a third reference pulse Pi is fed, the phase of which is different from the phase of the second reference pulse PJ. and the phase difference f2 between the two-pulse and stimulated echo signals is g / 2 - (, since ((Pr) Cf (P |) tfT / 2. Thus, for the second sample,

Vi-cj (x,) - (f (x2) + q (pi) -cj (pf) - -fi / 2 -lp;

BUT . (A1) 1 + (A) 4 + - (A1) 2 + (An) + 2A A sinlf. (five)

In this case, the squared amplitude of composite echo A is a function of sintf. In order to determine the desired phase difference C, it is necessary

Aoporn pulse P. At time Ј after pulse P, a composite echo amplitude is formed). The phase difference (between two-pulse and stimulated echo in this case is equal to

,) - tf (K2) + tf (p) - tf (P,) T / 2, (6)

therefore, the square of the amplitude Ak () is determined by the formula Aj (t) (A) 2

(BUT);

(A f

(A) 1

2A Aflcosyfc (7)

From formulas (4), (5) and (7) we find the desired expression

tgq

AtAk ()

BUT

At (t)

five

0

five

O

five

which allows to determine the phase difference (0. The amplitude and duration of the measured and test pulses must be standard, i.e. must exceed the threshold level of the amplitude limiter and the duration selector; the limit level is chosen so that the amplitude of the Han echo exceeds the noise level,

Inequalities and T -T (necessary to avoid suppressing a two-pulse signal with amplitude A proportional to exp (-2t / T2), and suppressing the stimulated signal with amplitude A proportional to exp (-T / T.j), respectively Ј T3 must be performed in order to prevent a superposition of Khanovsky echo and a free induction signal with a characteristic time T if Tj exceeds the dead time Tm of the detecting device. The inequality T T2 is necessary. To suppress the combination signals whose amplitude is proportional

e (-2T / T2) and which could be observed after exposure to pulses Pg and P on the first and second samples, respectively.

A device that implements the proposed method (Fig. 3) contains a block 1 for measuring the time interval between input pulses, selectors 2 and 3 of duration, shaper 4 controls — JQ X, and Xg. After arriving at the shaping pulses, the amplitude limiter 4 of the control voltage from the chitel 5, the generator 6 of the reference oscillations of the output of block 1, at the second output is triggered and the control voltage from the output of the block 1 is fed to the driver 4 and the block 12. According to the signals of the leading edge of the input pulses X and at the first output of the imaging device 4, two pulses with a fixed duration C are formed, which arrive at the selector 2 and gates the pulses

a controlled phase shifter 7, resonators 8 and 9 with samples, gated quadratic detectors 10 and 11, an arithmetic unit 12.

The input of the device is through a serially connected first selector 2 of duration, an amplitude limiter 5, a resonator 8 with a sample, and a gated quadratic detector 10 connected to the first input of the arithmetic unit 12, the second input of which is connected through a serially connected controlled phase rotation equalizer of the phase rotator 7 , on the tel 7, the resonator 9 with the sample and at the same time the gated quadratic detector 11 with the output of the amplitude limit of the pulse Pn corresponding to the formation of a swarm. When this pulse is applied, the phase of the signal passing through the file 5, whose input through the selector 7, changes to and / 2, the torus 3 is connected to the output 30, i.e. a reference pulse P is formed,

at

generator 6 reference oscillations, the input of the generator of control pulses is connected to the input of the device, the first output is connected to the control input of the first

In the absence of a control voltage, a phase change does not occur. At the output of zeroing the driver 4, a gating is formed

a selector 2 of duration, a second pulse, opening detectors 10 and a stroke - with a control input of the second 1 1 after the formation of a reference pulse — selector 3 duration, the third height Pn or P. a stroke - with a control input of phase rotation First impulse sequence

tel 7, fourth exit - from control X

The detector inputs 10 and 11, the input 40 of the amplitude limiter 5 on the resonance unit 1 of measurement b are connected to an input device 8 of the sample, and the second will be connected to the device, and the output to the second input of the pulses X, X, P1, P - of the spacer 4 and the third input block 12.

The device works as follows.

On the leading edge of the first measured pulse X, at the output of the zeroing of the former 4, a control pulse is generated, resetting the readings of the detectors 10 and P and locking them. In the absence of an output signal de. tectors 10 and 11, the output signal arithmetic phase shifter 7 to the resonator 9 of the sample, excites the signal Khanovsky

45 echo in samples (Figures 1a, b), which are fed to the inputs of gated quadratic detectors 10 and 11. The square of the amplitude of the Khan's echo at the moment of maximum is measured by the detectors 10 and 11

50 in the form of voltages equal to A2 and АЈ, respectively. Upon receipt at the input of block 12 of these signals in the calibration mode in the arithmetic unit 12

the metric block is also absent. The value of A is calculated (CO, and then

The leading edge of the pulse is set to 55 B; according to (8), the value of the block 1 is calculated, also in the zero state, v chenie (0, which goes to the output

which measure the in-device.

tormented t, When you receive a second, you can use the pulse X2 in the block as an example. 1 is fixed with samples using ferromagX, and Xg. After the control voltage from the output of block 1 arrives at shaper 4, the second output is triggered and the control voltage from the output of block 1 is fed to shaper 4 and block 12. The signals of the leading edge of the input pulses X and the first output of shaper 4 two pulses with a fixed duration C are formed, which arrive at the selector 2 and gates the pulses

world leader 4 two impulses of duration i are formed: the first of them

comes after a fixed time T after the impulse Xg, the second through T + (after the impulse X. The pulses of the second output of the former 4 are fed to the selector 3, in which

the reference oscillation coming from the generator 6, the reference pulses P x and P 2 are formed. At the third output of the imaging unit 4, a gating pulse is generated, which is fed to the control input of the phase shifter 7, for a time corresponding to the formation

pulse P „. When applying this impulse

In the absence of a control voltage, a phase change does not occur. At the output of zeroing the driver 4, a gating is formed

X,

P comes through

amplitude limiter 5 to the sample cavity 8 of the sample, and the second pulse sequence X, X, P1, P through the phase shifter 7 to the resonator 9 of the sample, exciting the signals of

echo in samples (Figures 1a, b), which arrive at the inputs of gated quadratic detectors 10 and 11. The square of the amplitude of the Khan's echo at the moment of maximum is measured by the detectors 10 and 11

in the form of voltages equal to A2 and АЈ, respectively. Upon receipt at the input of block 12 of these signals in the calibration mode in the arithmetic unit 12

the value of A is calculated (CO, and then

cobalt filming films. In these samples, a Khan's echo (nuclear spin echo) is observed at room temperature with a resonance frequency of f 216 MHz. The dead time of quadratic detectors Tm is 0.1 μs, which exceeds the time of non-uniform skewing T-, therefore the condition with T-j is replaced by the condition. The transverse relaxation time Tt is 25 µs, and the longitudinal relaxation time is T 120 µs. The duration of the pulses V, formed in the former 4 is 0.2 µs. The amplitude limiter has a threshold level of 20 mV. The time interval is T 30 μs.

In the calibration mode, instead of the measured pulses X and Xg, test pulses Kf and K2 of the same phase are applied to the input of the device (Fig. 2) and the dependence A (t) at Tm Т -Tg / 2 is measured by detector 11. Since the dependence of AK () is described by the expo, by the potential function A (1)

 Aoexp (-2Ј / T2), where the AO is determined by the parameters of the resonator with a sample, a program for calculating this function is entered into the arithmetic unit. After that, the device, whose circuit is depicted in Fig. 3, allows measuring the phase difference of radio pulses with a filling frequency of 216 MHz. The amplitude and duration of the measured pulses X and X, as well as the test pulses K and K, must exceed a level of 20 mV and a duration of 0.2 μs, respectively. The time interval between the leading edges of these pulses must satisfy the condition O, 1 μs Ј 1 2 μs.

The use of the proposed method of measuring the phase difference of pulses separated in time, as compared with the known, provides an extension of the frequency range, since the Khan's echo is observed at frequencies from 10 to 15 1S Hz.

Claims (1)

Invention Formula The method of determining the phase difference of electromagnetic pulses separated in time in one channel, including the formation of oscillations whose frequencies are equal to the frequency of filling the first and second measured pulses, characterized in that, in order to expand the frequency range, measure time inter. shaft Ј between these measured pulses, form the first pulse sequence with a normalized duration and a given constant amplitude, in which the first and second measured pulses after a certain time interval T after the second one are followed by the first and second reference pulses of the normalized duration, having an interval between them time (/ and zero phase difference, form a second sequence of pulses, in which the first and second measured pulses after the time interval T are followed by the first and third reference pulses of normalized duration, having between them a time interval Ј and a phase difference T / 2, the received pulse sequences are fed to the first and second samples, respectively, in each of which, at the filling frequency, respectively, after the second reference pulse and after the third reference pulse, after a time interval The first and second responses of the Khan's echo, the responses are selected, and then their maximum amplitudes A 4 and A are measured for the first and second samples, respectively, the phase difference Cp is determined dissolved in accordance with the formula A - A () tgCf l 2 l2 / A, - AK (O de А, ЛЈ) - the Khan's echo calibration amplitude, which is preliminarily measured, performed the listed operations on the second sample, - when instead of the measured pulses the first and second test pulses with the same phase and the normalized duration and a given constant amplitude are supplied, the time interval between which varies within T ,, T2 / g, where T 3 is the decay time of free induction in samples, T2 is the transverse relaxation time, and the time interval T satisfies the inequalities Tg.T.T ,, where T, is the longitudinal relaxation time in the samples. and hg PJ P2 FIG. 2 Fig.Z