SU761934A1 - Phase shift digital meter - Google Patents

Description

The invention relates to a digital measurement technology and can be used in automated test systems for measuring phase shifts in the circuits of 5 electronic devices and automation systems.

A device for determining the phase, containing a delay element, four logic elements and a trigger ζΐ ").

The disadvantages of this device are the narrow frequency range of the studied signals and the dependence of the measurement error on the frequency, as well as low noise immunity,

It is also known a digital device for measuring the phase shift of harmonic signals containing the first pulse shaper connected 20 through the first element of coincidence with a single input of a direct counting trigger, the second pulse shaper connected via a control trigger to the second input of the first element of a coincidence, second and third elements of a coincidence generator counting pulses, counter with indication, anti-coincidence element, the output of which

connected to the input of the counter with an indicator 30

2

and inputs with outputs of the second and third elements of coincidence, the pulse inputs of which are connected to the generator of counting pulses, with -. than the potential input of the second coincidence element is connected to the single output of the direct counting trigger, and the potential input of the third coincidence element is connected to the unit output of the control trigger and

zero input trigger direct counting [2].

The disadvantages of this device are relatively large measurement time 15, amounting to two periods of the investigated voltage, low immunity associated with the use of a control trigger. in the counting mode, which in the presence of noise in the voltage under study leads to the impossibility of performing measurements, limiting the device's application to analyzing only harmonic signals with equal 25 frequencies of the reference and researched voltages and the possibility of device readings failing due to the lack of synchronization and the time interval between the processes measuring and reading.

3 761934

voltage and _op through zero. The test voltage Ik, whose phase shift δχ is measured, is fed to the input of shaper 2, the output of which forms a sequence C of short pulses corresponding to the moments of positive transitions of voltage 11 through zero.

When 11 _{x is} delayed relatively and _op , i.e. 0 °. <Ψ _χ . <180 °, the pulse a £ of the sequence A passes through the coincidence element 3 and sets in one state the trigger of the .6 direct account, the high potential at the output of which opens the coincidence element 4, and through it to the anti-coincidence element 9 from the generator 8, counting pulses with a frequency begin to pass ( _o . After a time proportional, the pulse C / of the sequence C sets the control trigger 7 into one state, the high potential at the output of which opens the coincidence element 5, and through it 9 the drops begin to pass counting pulses from generator 8. The measurement process ends when a pulse b / of a sequence arrives; the zero trigger trigger 6 sets in and the control trigger 75 low potentials at the outputs of these triggers close elements 4 and 5 of coincidence, and anti-coincidence element 9 stop getting counting pulses.

Thus, measurement time T is equal to _N in this case half Τ _ση voltage period and _op i.e. T _m = 0.5, and the number of pulses Νφ registered by the counter is Νψ =) η _οη -η *), where η _ρη = 0.5 Τ _οη · G _о is the number of pulses passing during the measurement through the element 4 of coincidence, n _x = (0.5 ^ -1 x) ί ₀ is the number of pulses passing through-. over the measurement time through the element 5 matches. Consequently,

Νφ = \ · T _about , and since ίχ is proportional to ψίχ, the number of pulses Νψ recorded by the counter is also proportional to the measured phase shift Όχ,

When ahead of υ _οη , i.e.

-180 ° ί.'ΡχΖ.Ο ⁰ , after the next impulse b [of the sequence B comes the impulse, of the sequence C,

then the pulse of the sequence A. In this case:

ⁿ ° 0. 0. 5 Τςχι 'ίο ΐ ^п х = (0.5 Τ _οη +) · ₀ · ₍

= ( ^P op " ^π χ) = Ιχ · |

those. Νφ is proportional to Ψχ, and the measurement time is T _and = 0, 5 + ίχ and since the Maximum value of 1 _X does not exceed 0.5 Τ _οη , then T _m £ Top ·

Information about the sign 4> _{x is} displayed on the indicator 13 characters, which

set to the state corresponding to the voltage level on its

The purpose of the invention is to improve the performance and noise immunity of the device.

This goal is achieved by the fact that in a digital device for measuring the phase shift, containing the first pulse shaper, connected through the first element of coincidence with the single input of the direct count trigger, the second pulse shaper, the second element of the coincidence, potential, _

the input of which is connected to the output of the direct-count trigger ¹⁰ , controlling the trigger. whose output is connected to the potential input of the third coincidence element, the anti-coincidence element connected by its inputs to the outputs 15 of the second and third coincidence elements, the pulse inputs of which are connected to the output of the counting generator, pulses and a counter with indication, connected by their first input to the output of the 20 Dy anti-coincidence element, entered a three 'ban, a sign trigger, a sign indicator and a count indicator, and a zero input trigger the ban is connected to the output of the first element of coincidence, 25 and the output is connected to the potential input of the first element of coincidence, the output of the second pulse shaper is connected to the single inputs of the inhibit trigger, the control trigger and the sign trigger, the output of the sign trigger is connected to the potential input of the indicator 'connected to the output of the first element' coincidence, while the second 'output of the first pulse shaper is connected to the zero inputs of the sign trigger, the control trigger and the direct count trigger, connected by the output to the first input of the counting indicator, the second input of which is connected to the output of the control trigger, and the output to the control input of the counter with indication. .....

The drawing shows a functional diagram of the device. 45

The digital device for measuring the phase shift contains the first pulse generator 1, the second driver 2 pulses, coincidence elements 3-5, forward count trigger 6, controlling “θ trigger 7, oscillator 8 counting pulses, anti-coincidence element 9, counter 10 with indication, trigger 11 prohibitions, trigger 12 characters, indicator 13 characters and indicator 14 accounts. _

The device works as follows ³³

in a way.

The reference voltage and _op is supplied to the input of shaper 1, at the first output of which a sequence A of short pulses is formed, corresponding to 60 transitions corresponding to the moments of positive voltage and _Op through zero, on the second output - sequence B of short pulses corresponding to the moments of negative transitions

761934

potential input, pulses cp ~, of succession A passing through element 3 of coincidence. The pulses of the sequence C establish the trigger of 12 characters in one state, the output of which is connected to the potential input of the indicator 13 characters.

Setting the trigger 12 'to the zero state is carried out by pulses of the sequence B. When 0 ^o <4? _x <

<180 ° by the time of arrival of the pulses of the sequence A, the trigger 12 of the character is set to the zero state and a minus sign is recorded in the indicator 13 of the character. At -180 ° 2 φχ / 0 °, by the time of arrival of the pulses of sequence A, the trigger 12 of the sign is set to one and the plus sign is written in the indicator of the 13th sign.

The protection of the testimony of the proposed device 20 from failures when the voltage Ι'χ is lost is provided by the coincidence element and the inhibit trigger, which is set to zero state by the next pulse of sequence A and prohibits the passage of the following pulses of this sequence until the next pulse of the sequence C arrives. On display30 of counter 10 and indicator 13, the last measured value and the sign of Φχ are displayed. This allows you to measure the lag of single signals.

The noise immunity of the proposed 35 device increases due to the fact that the control trigger 7 is transferred to one state by the first pulse of sequence C following the next pulse of sequence B and does not respond to the remaining 40 pulses of sequence C until the end of the measurement cycle. shaper 2, the mathematical expectation of the value can be determined by statistical methods for a sample of meter readings.10.

Since in each measurement cycle the circuit responds only to the first intersection with a voltage of 1C zero level, the proposed device 50 allows measuring the phase shift of voltages whose frequency is a multiple of O _op . ·

Protection of device readings from failures is ensured by synchronization _ς

process accounts and output information *?

using the count indicator 14, performing the logical addition of the output potentials of the trigger 6 and 7. The count indicator 14 displays the measurement process and simultaneously controls the operation of the counter 10, ensuring the timely output of the 4 ” _x value counted by the counter 10 on its indicator and preparing the counter 10 to a new measurement cycle.

Introduction of NF elements - a ban trigger, a sign trigger, a sign indicator and an account indicator, and ^; New connections increases its noise immunity, doubles the speed, expands the scope, increases the functional reliability of the device and the reliability of measurement results. The proposed device can be used both autonomously and as part of automated test systems to monitor and study the phase characteristics of complex electronic devices and automation systems in established and transient modes.

The use of the proposed device will reduce the range of measuring devices and significantly improve the efficiency of test systems.

Claims (2)

Claim Digital device for measuring the phase shift, containing the first pulse shaper connected via the first element of coincidence with the single input of the direct counting trigger, the second form; the pulse changer, the second element of coincidence, the potential input of which is connected to the output of the direct counting trigger, controlling trigger, the output of which is connected to the potential input of the third coincidence element, an anti-coincidence element, connected by its inputs to the outputs of the second and third coincidence elements, whose pulse inputs Connected to the output of the generator of counting pulses, and a counter with indication connected by its first input to the output of the anti-coincidence element, which is characterized by the fact that a prohibition trigger, a sign trigger, an indicator indicator and a counting indicator are introduced in order to improve performance and noise immunity, the zero input of the inhibit trigger is connected to the output of the first element of coincidence, and the output is connected to the potential input of the first element of coincidence; the output of the second pulse shaper is connected to. single inputs of the inhibit trigger, and a control trigger and a sign trigger, the output of the sign trigger is connected to the potential input of the sign indicator, the pulse input of which is connected to the output of the first coincidence element, while the second output of the first pulse shaper is connected to the zero inputs of the sign trigger, the control trigger and the trigger direct account connected by the output to the first input of the account indicator, the second input of which is connected to the output of the control trigger, 761934 and the output is to the control input of the counter with indication. Sources of information taken into account in the examination 1. French application number 2271580, cl. From 01 to 25/00, 1/16/76. 2. USSR author's certificate number 596892, cl. From 01 to 25/08, 1976.