SU1239640A1 - Device for measuring non-linearity of sawtooth voltage - Google Patents

Abstract

The invention relates to a radio metering technique and is intended to automatically measure the nonlinearity coefficient of a sawtooth voltage in television, radiolocation, oscillography, to monitor and measure the dynamic error (nonlinearity of conversion) of digital-to-analog converters, etc. For this purpose, an indicator 13, a generator of 2 counting pulses, elements AND 3, II, counter 4, driver I, - control unit 14, reversible counter 12, amplitude detector 5, comparators 10 and 8, generator 7, digital analog converter 6 and divider 9 voltages. The D / A converter 6, the generator 7, the comparator 8 and the divider 9 are a functional converter. The measurement is carried out over three periods of input voltage. 1 il. with the next oo; about O5 4

Description

f

The invention relates to the field of radio metering technology and is intended to automatically measure the nonlinearity coefficient of a sawtooth voltage in television, radiolocation, oscillography, as well as to control and measure the dynamic error (nonlinearity of conversion) of digital-analogue converters, etc.

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

The drawing shows the functional scheme of the device.

A device for measuring the non-linearity of the sawtooth voltage comprises a driver 1, a counting pulse generator 2 connected in series, a first element AND 3 and a counter A; amplitude detector 5, digital-to-analog converter 6, step voltage generator 7, comparator 8, voltage divider 9, comparator 10, second element 11 of the series 11, reversible counter 12 and indicator 13 of control unit 14. Moreover, the digital-to-analog converter 6, the generator 7, the comparator 8, the divider 9 can be called a functional converter (shem.

The device works as follows.

In the initial state at the output of the counter 4, the zero code is set, the number K is written in the reversible counter. The measurement is carried out over three input voltage periods. From the device input, the sawtooth voltage is fed to the input of the driver, which generates pulses whose duration is equal to the duration of the forward stroke of the voltage under study. During the first period of the input voltage, a rectangular pulse generated at the first output of the former opens the first element I 3, and the pulses from the generator 2 of the counting pulses with a period T. enter the counter 4. At the end of the forward stroke, the counter 4 records the number impulse M, passed at its input, which can be determined by the formula

M (1)

si

Simultaneously, the amplitude detector 5 detects the maximum value of the input sawtooth voltage

396AO2

Um. During the second working stroke of the voltage under investigation, a rectangular impulse is formed at the third output of the former 1 and the 7th step voltage generator begins to form a linearly increasing stepped voltage V, which is fed to the input voltage of the digital-to-inverter 6 voltage converter the input of which is written the number M, proportional. the duration of the direct course of the voltage being investigated. At the output of the digital-to-analog converter 6, a 15 step-increasing voltage is formed, the value of which is determined by the formula

and

DAC

,

(2)

where n is the digital-analogue width

converter This voltage is compared on the comparator 8 with the voltage at the output of the amplitude detector 5. At the time of comparing these voltages, the comparator 8 generates a pulse to stop the generator 7 of the step voltage. The voltage at the output of the generator 7 can be determined by the formula

(2): gfy conditions Uu, An and „, i.e.

and sz)

 GSN M

This voltage through the voltage divider 9 with a division factor of 0.1 is fed to the input of the comparator 10.

g during the third period of the input voltage, the counting resolution impulse from the second output of the imaging device enters the E1 input of the second element 11, its other input receives counting pulses with a period of 0, 1 T from the second output of the generator 2 counting pulses and the third input of the element. And 1I comes the enabling pulse from the comparator 10, which locks the element at the time of comparing the input test voltage with the output voltage of the divider 9.

The initial velocity of the input sawtooth voltage can be determined by the formula

V ..

 2,

W

where and, 1 Uj is the output voltage of the functional converter 6; t is the pulse duration at the output of the comparator 10.

The pulses from the output of the second element And 1 1 are fed to the reversing input of the reversible counter 12., in which the number K is pre-recorded. At the end of the third forward stroke of the voltage under study, the output of the reversible counter 12 is formed by the code N, defined as

N K - P,. (five)

where P is the number of pulses ts passed through the second element AND 1U

Taking into account formulas (1), (3) and (4), the number N can be defined as

M-V -V Jcpn

 Ott-t;

0.1 t, k - 2il-y ii k - 2Ai-Ub.B

0.1 T, „V, m-0.1 T ,,. V ,.

K-2L1-I.v.1. (6) t ,, .. 0,1. t ,, - vh

Given that the average rate of increase of the sawtooth voltage

wed

Hiru

expression (6) can be rewritten

N

K -.

Vcp

then

N

TO

v

to 4,

where is the nonlinearity coefficient of the sawtooth voltage. Code N at the output of the reversible counter. 12 is indicated by an indicator 13.

Claims (1)

Invention Formula Device for measuring the non-linearity of the sawtooth voltage, Editor L. Gratillo Compiled by V. Antokhin Tehred M. Khodanych Proofreader of Reshetnik Order 3391/45 Circulation 728 Subscription VNIIPI USSR State Committee for inventions and discoveries P303.5, Moscow, Zh-35, Raushsk nab. D. 4/5 Production and printing company, Uzhgorod, Projectoj st., 4 396404 holding indicator, series-connected counting pulse generator, first AND element and counter, as well as a driver, whose input 5 is the device input, and the first output is connected to the second input of the first And element, the second And element, the first input of which is connected to the second generator output counting pulses, and the second input is connected to the second output of the driver and the control unit, the output of which is connected to the control inputs of the driver and counter, characterized in that, in order to improve the accuracy ten 15 measurements, a reversible counter is entered into it, the counting input of which is connected to the output of the second element AND, the setting input is connected to the output of the control unit,. and the output is connected to the input of the indicator, the amplitude detector is connected to the input of the device, the detector and the first comparator, the output of which is connected to the third input of the second element, and the second comparator, the first input of which is connected to the output of the amplitude detector to the output of the control unit, the first control input is connected to the third output of the driver, and the second control input is connected to the output of the second comparator, a digital-to-analog converter, information ny input of which is connected to the output of the counter, the output is connected to the second input; second-comparator, a reference voltage input coupled to the output of the generator and the step voltage input of the voltage divider whose output is coupled to a second input of the first comparator.