SU782158A1 - Device for monitoring parameters of quick-action analogue-digital converters - Google Patents

Description

(54) DEVICE CONTROL PARAMETERS

QUICK OPERATION ANALOG-DIGITAL CONVERTERS INVENTORY The invention relates to a pulse technique. A known meter for the dynamic parameters of analog-to-digital converters (ADC) contains a generator of a periodic voltage, a digital signal processing circuit, an ADC, a frequency divider, an amplitude-phase regulator, and Rp elements. The disadvantage of this device is the lack of speed and accuracy. The closest in technical essence to the proposed VL is a device containing a harmonic calibrated signal generator, the output of which is connected to the input of a controlled ADC, a generator of very high sampling signals, a trigger clock, and a 2j indicator. The disadvantage of this device is the low accuracy of measurement of the dynamic error. The purpose of the invention is to demonstrate the accuracy of control at the limiting frequencies of the spectrum of the input signal. By the way, the device allows measuring the errors for dynamic error, ADC, such as aperture error and under-discharge error. The goal is achieved by the 4to device containing a harmonic calibrated signal generator, the output of which is connected to the input of the controlled ADC, the generator of calibrated sampling signals, the start key and the indicator l, three elements And, two RS-flip-flops, a counter with a decoder, memory registers and a digital KOfciapaTop with a zshatchkom code whose output is connected to the first inputs of a digital comparator, BTOPiae whose passage is connected bitwise to the outputs of the ADC and the inputs of the regis memory circuits whose outputs are connected to the indicator inputs, the first inputs of all elements And are connected to the generator output of calibrated sampling signals, the second inputs of the first and second elements And are connected to the output of the first RS flip-flop: and the output of the digital comparator, the second input of the third element And connected to the output of the second RS flip-flop by the first input of the decoder, the inputs of which are connected to the outputs of the counter and the C input of the memory register, the jS input of the first RS flip-flop, the R input of the second RS flip-flop counter connected to the key OSCAL, C-input of the counter is connected kvyhodu third AND, S-input of the second RS-trigger is connected to the output of the second AND gate, the output of the first element and is connected to. The ADC sampling input and the C inputs of the second and third memory registers are connected to the decoder outputs. -. ,

FIG. 1 shows the structural electrical circuit of the proposed device; FIGS. 2 and 3 show the times of our diagrams explaining his work.

The device contains a generator 1. harmonic calibrated signal, generator 2 calibrated signals 6, discretization, key 3 start, 15 digital comparator 4, unit 5 codes, elements 6, 7, 8, RS-flip-flops 9, 10, counter 11, decoder 12, registers 13, 14, 15 memories, indicators 16, 17, 18, control ADC 19

The essence of the device operation is to feed the measuring signal to the ADC input, to register and further process three consecutive codes nj 1 e to the ADC output after the preset control code n matches the code n at the ADC output (Fig. 2). If the sampling pulse frequency For an analytic description for measuring the fiprp signal is known, then by setting a control code equal to code n and taking place at a certain t-th sampling pulse, you can determine a hypothetical calculation and calculation code at the output of the ADC Ci 35 coo respectively for 1 + 1, 1 + 2 and 1 + 3 sampling pulses. Comparison of the code n | ,, registered in the experiment with the hypothetically calculated code r1, allows the amount of .j. with accuracy Ш |, where h is the quantization liiara value, estimate the adamine error of the ADC dk for a 6th determined quantization level. The use of registered code is discussed below. | 45

To obtain the numerical value of the magnitude of the dynamic variability, it is necessary to go from the codes lif and n to the corresponding amplitudes of the input signal. The absolute value of the measured error rfk (n is determined by the formula:

"one. (PG,} - 1 Ant - Ant, | - () where Ar is the measurement value

the signal calculated for jS of the registered experimental value of the calculation code n, corresponds to the left (1 + 1} th sampling pulse;

An, - the value of measuring sig-bo

I1, calculating the value for the theoretical value of the calculation code ntrtf of the corresponding (l + 1) -Mfffift 3ibs sampling; 65

(gu) - static error

The ADC measured for the quantization level corresponds to the theoretical value of the calculation code p.

When using a harmonic measuring signal described by the expression X (t) As I n (t + S), its nonlinearity can lead to ambiguity in the measurement of the calculation code, i.e. to reduce the accuracy of the device. The magnitude of the ambiguity varies in / depending on the ADC size and the ratio of the frequencies of the measuring signal and the sampling signal. To eliminate the ambiguity of the samples and to ensure the specified accuracy, it is necessary to require that the sampling frequency be determined in the experiment by the ratio

9, x, where Hgiit is the frequency of the measuring signal;

6x additional component, selected from the ratio

A g / 2 -1o;

N is the size of the ADC under test.

In order to increase the reliability of the measurement results by eliminating the effect of random high-frequency components on the measurement signal, it is proposed to register the codes at the output of the ADC. When the frequency ratio is N and e, selected in accordance with the above expression, and there is no methodological error of the experiment due to random factors, codes n and n as well, n; must be equal to each other.

In order to determine the aperture error, the control code should correspond to the quantization level at which the slope of the measuring signal is maximum and the magnitude of the measurement signal is between 1 and {1 + 1) sampling pulses. To determine the error of undercharging, the assigned control code must correspond to the maximum (minimum) of the dynamic range of the transducer to be tested and the minimum slope of the measuring signal.

The device works as follows. raes "{.

Claims (2)

1. Authors certificate of the USSR 472454, cl. H 03 K 13/17, 25,05,71. 2. Avtometri, 1976, No. 5, p. 83