SU1256202A2 - Device for measuring distribution function of random error of analog-to-digital converter - Google Patents

Abstract

The invention relates to instrumentation, can be used for experimental research and control of the error of analog-to-digital converters (ADC) and digital voltmeters and is an improvement of the known device according to ed. No. 683015. The purpose of the invention is to expand the field of application of the device by providing the possibility of estimating the variance of the random error — in that the device containing the source of calibrated voltages, a voltage summation unit, a code converter — a search, a code comparison element, a reversible counter, the first adder, controlled pulse generator, counter, counting unit, memory block, first switchboard, arithmetic unit executed on the block of NE elements, inverter, second switch, V is entered rum adder, and register delay element. The variance estimate is generated by the arithmetic unit by accumulating the results of multiplying the Nyj values generated by the counter, and the sgn values (h-N) of the codes generated by the comparison element. 1 il. with

Description

The invention relates to instrumentation engineering, can be used for experimental research and control of the error of analog-to-digital converters (ADC) and digital voltmeters — and is used to improve the device according to the auth. No. 683015.

The aim of the invention is to expand the field of application of the device by making it possible to estimate the variance of the random error,

The drawing shows a block diagram of the device. ,

 The device contains a calibrated voltage source 1 (TSC), a voltage summation unit 2, a code-voltage converter 3 (PKN) code comparison element 4, a reversible counter 5, a first adder 6, a controlled pulse generator 7, a counter 8, conversion block 9, memory block 10, first switch 11 and arithmetic unit 12 controlled by ADC-13. The arithmetic unit contains a block of 14 elements NOT, an inverter 15, a second switch 16, a second adder 17, a register 18 and a delay element 19.

The device works as follows.

In the initial state, at the output of source 1 there is an exemplary voltage UQ Hz (N + 0.5), equal to the nominal value of the N boundary, (N-J-I) -M quanta of the controlled ADC 13 (- nominal quantum size). A secondary code (N + 1) is applied to the second input of the code comparison element 4 from the corresponding terminal, the pulses from the output of the generator 7 are not received, the counters are reset to the zero state. The Start signal at the output of the generator 7 appears pulses, periodically starting the controlled ADC 13 and forming the output of the counter 8, a time-varying code N, which transforms the PKN 3 into a stepwise change of the auxiliary influence V. This influence is distributed within 1 -2 qc and is centered relative to the reference voltage, with which it is fed to the input of the ADC 13.

Formation of the evaluation code of the systematic component of the instrumental error of the ADC. 13 at the output of the reversible counter 5 is inherently analogous to the algorithm in a known device.

The occurrence on element of element 4 of the signal h N corresponding to the event, when the error of the ADC is 13 and less than the estimate of the systematic error, the code equivalent of which is formed by a reversible counter, causes its content to increase by 1. Thus, through feedback through block 4, reversible counter 5, adder 6,

PKN 3, block 2 summation of voltages and ADC 13, the device achieves balance, i.e. equality of probabilities of occurrence of events h $ N and h N. At the same time, equality of the uj to the true value is automatically ensured, i.e. the instrumental error of DACP 13 is centered. In the corresponding cells of the unit 10.pam are accumulated at

this signals h N characterizing the sign of the difference (Aj -V,). Thus, in the cells of the block 10, the values of the ordinates of the integral distribution function FU (VJ) errors are calculated

ADC, Control of the process of recording signals h N into the cells of block 10, is carried out by a code from the output of the counter 8. Estimation of the dispersion is formed by the arithmetic unit 12, which implements the algorithm

 Ah, NV. sgn (sj-vj yj

Where

J4 A Q

sgn (uj-vp

signal spreads of a uniformly distributed auxiliary action; the volume of the sign in the processing of statistics sign function, reflecting the relative. above; neither values of instrumental error and auxiliary influence at the j-th instant

sgn (uj -Vj),

1 with i N

 J

-1 with g Nj.

The considered algorithm is implemented using the available signals in the proposed device.

A2 +

odG ", sgn (ti

Q i J

; -N),

Where

sgn (hj-n)

,

with hj

N or uj V with hj i N or uj 6

by accumulating the results of multiplying the values of Ny generated by the counter 6, and the values of sgn (h-N) generated by the code comparison element 4.

The operation of generating the value of the product is carried out in the arithmetic unit 12, the second switch 16, together with the block 14 of the elements HE. In this case, the block 14 generates the inverse values of the auxiliary influence, and the second switch 16 transmits to the first input of the second adder 17 either direct or inverse values of the influence Ny depending on the result of comparing the codes h and (Nt-1) in element 4. Thus, The input accumulator adder consisting of the combinational adder 17 and register 18 receives the product code Ny: sgn (hj -N). To ensure correct reading, in the case of sgn (hN) -1 an additional reverse code is fed to the accumulator. The addition operation is organized by using the third input (CI transfer) of the adder 17. The accumulative summation is organized using register 18, which stores the current sum code, and feedback to the second input of the adder 17. Clocking the operation of register 18 should be carried out along the circuit from output generator 7 through the element 19 delay.

Ny code; from the output of counter 8, is actually the current level j of quantization of the quantized auxiliary effect, changed from 1 to k. The effect itself, as a dimensional quantity, is described by the relation V (k + 1) / k. Then the expression for estimating the variance of the error of the ADC 13 is

from 9D

  A sgn (hpN)

X J si JJ

- IQ + 4Г i: (i / k) sgn (h .. -Y,

0

five

0

five

0

five

0

five

0

five

where is ink

Q; and j is the number and number of quantization steps of the auxiliary effect; the number and number of the measurement produced by the ADC 13 for each value (usually Q; 10); Q Qi. k. .

In the metrological aspect, the information in the sum of ZCi / k) sgn (h ;; -N) is of the greatest value, since it is the one that is variable from the change of the measured parameter (dispersion), the other members of the last expression are constant. Therefore, it is sufficient to limit the consideration of the issues of hardware implementation of this amount. In this case, the accumulated amount is proportional to the desired value of the estimate of the variance D th.

In the hardware implementation of the algorithm for measuring the dispersion of a volume of sampling Q, the recalculation factor of block 9 is divided, the summation result is divided by Q by selecting the capacity of the accumulating adder to be Q. The pop-up sum is always smaller than Q, because (i / k) s1, therefore the result measurements are obtained in K units. Taking into account that the term (i / k) is expressed in K parts, it is convenient to choose the capacity of adder 17 equal to K and increase it with a binary reversible capacitance counter Q (for example, two 564IE11 microcircuits), counting overflow signals with with Odmator 17. The direction of counting in plus or minus is determined by the signals from block 4 of the code comparison. In this case, the first term in the php unit: parentheses can be taken into account by constantly including when indicating 1 in the whole part of the displayed result (i.e. having included 1 permanently in tenth digit). Multiplying the sum by 4 can be done by shifting to the right the result obtained in the binary counter using the shift register (two 564IR2 chips).

Block 14 and inverter 15 can be implemented using integral

155LN1 and 564LN2 microcircuits, the second switch 16 can be made with the 564LS2 microcircuit (four AND-OR elements), the second adder, 17, and the register 18, which form the 1st accumulator, using the ZbAIM and 564ИР2 microcircuits, respectively.

- -W

Thus, the proposed device allows to expand its area of application due to the possibility of directly estimating d1-5per sions of one of the most important random error and the ADC characteristics fixed in the normative documents.

Claims (1)

Formula invented A device for measuring the distribution function of the random error of analog-to-digital converters according to the author. No. 683015, that is, in order to expand the field of these random errors, an arithmetic unit is inserted in it, executed on the block of elements NOT, the inverter, the second switch, the second adder, register and delay element, the first information input of the second switch is combined with the input of the block of elements NOT and is connected to the output of the counter, the output the block of elements is NOT connected to the second information input of the second switch, the output of which is connected to the first input of the second adder, the second input of which is connected to the output of the register, and the output to the first input of the register, the second ByioR of which is connected through the delay element to the output of the controlled generator pulses, the third input of the second adder is combined with the first control input of the second switch and connected to the output of the inverter, the input of which is combined with the second control input of the second switch and connected to the inverse to the output of the comparison code element. Editor And, Shulla Compiled by B, Solodova Tehred L .Kravchuk: Corrector. Cherni 4836/57 Circulation 816 Subscription VNSHPI USSR State Committee for inventions and discoveries 113035, Moscow, Zh-35, Raushsk nab, 4/5 Production and printing company, Uzhgorod, st. Project, 4