SU375581A1 - METHOD OF ALLOCATION OF TIME INTERVAL, - Google Patents

Description

one

The invention relates to the field of phase-measuring technology and can be used to create infra-low-frequency phase meters and instruments for determining rotational derivatives in aerodynamic measurements.

Known methods for extracting a time interval proportional to the phase shift between two harmonic signals, based on the use of threshold elements (null organs, square pulse drivers), do not provide high accuracy due to fluctuations in the trigger points of the threshold elements, due both to interference and I1 derivatives of harmonic signals, depending on amplitudes.

The purpose of the invention is to reduce errors in the determination of the time interval, the proportional phase shift between two harmonic signals, due to the presence of interference and the variation of amplitude-dependent harmonic signals.

This is achieved by excluding threshold elements from the scheme and allocating a time interval that is prolortional to the phase shift based on integrating the signals under study during the const time, with TI being selected on one of the half-periods of the signals under study, the difference of the intervals is stored until time / s is again integrated, and the result is compared with the previous value. At the moment of equality of the integrals, two pulses are formed, the time shift between which is proportional to the phase shift between the signals under study. Let the harmonic signals under study have the form

F,, sin wt t F - FO sin (/ - cp) (1)

As a result of their iteration over time TI, we get

“2

FjTj: F smwtd (- (cosm, - coscu / j).

F, (.J F ,, sin (u,) - X

20

X (coscDjfj-cos 0) 2) (sinm-sincu / i). (2)

0)

The integrals L (t) 4 and FZ (T :) over time T2 and t.z will respectively

гF

FI (t) - FO, Sin shY (- (COS., - COS with /).

30 P. (-3) „Sin (w - cp) X X X (cos 0), - cos Mifs) - (ssh /, - sin). From the condition of equality -fi (t2) and 2 (T2)), it is possible to STOP U AND 5/4 - arccos (cos Ш4 + cos «- cos, ifj - -jarccos cos 9 (cos Ш, + cos« 4 Ш Ш (U - COS W /,) -f Sin cp (sin 0), + sincBia - sin u) j. (4) The expressions for 4 and 4 do not depend on the amplitude of the signals under study, and if conditions are accepted for a positive half-period. , No., -; w / 5 - tg; 0) - Joo for the negative half-period of 3117 CDjfj zr: - t :; (s ™ (6) 2bo 4 +, a This indicates that TI is equal to the difference between the time t and is proportional to the phase shift between the harmonic signals under study. In the drawing, the block diagram of the device for performing the method. The circuit contains sensors /, keys 2 and 3, reversible counters 4 and 5, time master 6, scheme OR 7, output bus 8, input buses 9 and 10, and start bus 11 pulse. In the initial position, keys 2 and 3 are closed and reversible the counter is in zero states. The device operates as follows. A pulse start on the bus 11 time setter creates a time interval T on which the keys 2 and 3 are opened. The time setter also binds the set time of the master signals to a positive (negative) half-period of the harmonic signal coming through the bus 9. In for ti counters 4 VI 5 work on and the addition of pulses postulated to their inputs from frequency sensors (3) /. The contents of the counters are proportional to the integral values of the functions during the time TI. In the next positive (negative) loluperiod of the signals under study, the time master opens keys 2 and 3 at time ia. Now counters 4 w. 5 work on the subtraction of input AND pulses. At the moment of time when the contents of the counters become equal to zero, which corresponds to the equality of the integral values of the functions in the first and second integration sections, pulses appear at the outputs of the counters, the time shift between which determines the phase shift between the signals under study. Thus, the selection of a time interval proportional to the phase shift is carried out over two periods of the harmonic signals under study. Subject of the invention. A method for allocating a time interval proportional to a phase shift between two harmonic signals using a time unit, characterized in that, in order to reduce errors caused by interference and a change in derivatives, depending on the amplitude of harmonic signals, w obtain a linear 3; time interval and phase shift, integrate the values of each harmonic signal in two time portions with. master of time intervals and integrators, and determine the time interval by extracting the difference between the moments of equality and integral values of each harmonic signal in the two integration regions using logic elements, and the beginning and end of the first interval of integration are taken equal to - and - t. for a positive half-period of the harmonic signal and, respectively, equal - AND - for the negative half-period, and the beginning of the second integration interval is - for the positive half-period and - for the negative half-period of the output harmonic signals, and the time setting signals of the time source tie to the positive (negative) half period of harmonic signal.