SU748273A1 - Phase shift measuring method - Google Patents

Description

one

The invention relates to information technology, in particular, to the field of phase measurements, and can be used to measure the phase shift between two periodic signals to obtain a result in the form of a digital code suitable for input into a digital computer.

A known method of digital measurement of the average value of the phase shift is based on counting the number of quantizing pulses grouped in bundles whose duration is proportional to the phase shift between the studied oscillations and inversely proportional to their frequency and which pass to the counter input for a measuring time short period of quantizing pulses l.

However, this method is characterized by reduced measurement accuracy due to the fact that in the general case the time interval proportional to the phase shift between the oscillations under study is not a multiple of the quantizing sequence period, and the period of the oscillations under study is not a multiple of the measurement time ..

There is also known a method for measuring the phase shift, based on a comparison

in time of short pulses formed from the signals under study, with short pulses of the reference generator, whose frequency is close to

 the frequency of the studied signals, and the allocation of the time interval between the output pulses of the coincidence circuits, equal to the time interval proportional to the angle of phase shift, to the knife by an integer 2,

The disadvantages of this method are the accuracy of the measurement result, due to the possibility of non-fixing the moment of coincidence of the pulse of the reference generator with the pulse formed from the signal under study, in the case of a small amount of overlap of the said pulses; strict requirements on the duration and form of the pulses compared in time, due to the requirement of obtaining single matches.

The purpose of the invention is to improve the measurement accuracy.

And the goal is achieved by measuring the phase shift based on transforming the phase shift to a low frequency by comparing time sequences

30 pulses generated from the studied signals, with a reference sequence of pulses and a subsequent time-pulse conversion time intervals proportional to the desired phase shift and the period of the studied signals, to generate fpSttKfU of the mentioned time intervals using the corresponding selected, equal-order pulses in sequence -the matching matches.

Figure 1 and 2 presents the scheme of implementation of the method.

 The device diagram (Fig. 1) contains drivers 1 and 2, elements 3 and 4 of coincidence, blocks 5 and 6 of selection, block 7 of automatic frequency control, controlled oscillator 8, driver 9, trigger 10 with counting input, symmetric trigger 11, time selectors 12 and 13, counters 14 and 15 pulses.

the measurement is made as follows. The analyzed periodic signals with a frequency of Jex-Forming 1 and 2 are converted into inhomogeneous series of rectangular pulses of duration с with and period

The T &% 1 / -pulses of the input and output sequences are equally tied to the phase of the signals under study Tb between them and the desired phase angle with the corresponding time shift ty is stored between them. Next, the input pulse sequences are fed to the first inputs of elements 3 and 4 of coincidence, to the second inputs of which from the controlled generator 8, whose frequency η is close to the frequency of 1 in the investigated signals, through the driver 9 of the input isT, the reference sequence of rectangular pulses of duration tx and with a period of Trp-

Then, if the duration is from the pulses of the input and support sequences. Satisfies the following conditions

(one)

g (

-sG (2)

at the outputs of elements 3 and 4 they form the e pYo 1 yo (s: y: and the following coincidence packets, the number of impulses in which is proportional to tr and inversely proportional to the difference | TBx-Top1

The fulfillment of the condition, (i) is necessary for the radiation at the outputs of elements 3 and 4 of the packet matches. The fulfillment of condition (2) results in a c-lrioWft and a coincidence in time of them in the input and reference fields.

With the help of block 7, the frequency of the generator 8 is kept close to the formers 1, 2, and 9 of conditions (1) and (2). Packages

matches from the outputs, elements 3 and 4 proceed further to blocks 5 and 6. The function of the latter is to distinguish the same order of following the i-th pulses of a match packet, the time interval between is proportional to TC,.,. and does not depend on the duration -tg.

In the method of measuring the phase shift, the transformation of the desired phase shift to a low frequency (frequency of matching packets) takes place.

Depending on the phase advance or lag of the follow-up signals, the order of operation of elements 3 and 4 changes and, as a result, the order of arrival at the inputs of a symmetric trigger 11, which forms a time interval in the device proportional to the desired angle of phase shift 1}. And the trigger 10 in the device performs the function of forming the time interval Td. With the help of time selectors 12 and 13, the time intervals are respectively filled with quantizing pulses of a supporting sequence with a TQP period, the number of which is TB-Pop and tip is counted by counters 14 and 15 pulses. The value of the desired phase angle is determined by the formula.

 . 360 °

 .op.

The phase meter depicted in FIG. 2 consists of shapers 16, 17 and 18, a controlled oscillator 19, an automatic frequency control unit 20, logical elements 21 and 22 I, selection units 23 and 24, electronic, switch 25, coincidence indicators 26, 21 , a blocking block 28, a trigger 29 with a counting input, a symmetric trigger 30, a first key 31, a second key 32, pulse counters 33 and 34, and an arithmetic node 35.

Phase meter works as follows. The reference and measured voltages, respectively, are fed to the formers 16, 17. In addition, the voltage of the auxiliary frequency fgj comes from the controlled oscillator 19 to the driver 18. close to the frequency {g input voltages. Shaper 18 Auxiliary sequence of rectangular pulses of duration t and period T.

1 / kpblock 20 automatic adjustment

frequencies. The inputs of which receive one of the sony voltage voltages and frequency i, maintain the frequency tatn of the output voltage of the auxiliary frequency controlled oscillator 19, close to the frequency tv, the input voltage, the reference and the measured square pulse sequence are fed to the first the inputs of the logic elements 21 and 22 And, respectively, the second inputs of which receive an auxiliary sequence of pulses, packets of matches Un, and L) ng are formed at their outputs

Packages of owls, drops Opts of the elements 21 and 22 arrive at blocks 23 and 24. From the output of block 23, the selected first pulses of two consecutive packets arrive at the input of flip-flop 29, which forms the time interval T, which is quantized with pulses with a period of Tsp. quantizing pulses that fill the time interval, count: it counts 33 pulses.

Type values are entered into the arithmetic node 35, where by the formula

V.360 °

determines the desired phase angle

The positive effect of using the proposed method is to increase the reliability of the measurement result while reducing the requirements for the duration and shape of the pulses compared with time. In this case, the requirements imposed on the parmeters of individual units of devices that implement the present method are reduced, which increases their manufacturability and reduces cost.

Claims (1)

1.Smirnov P.T. Digital phase meters. L. Energie, 1974, 33. 2, USSR Copyright Certificate 324588, class: q 01R 25/00.