SU1216828A1 - A.c.voltage-to-digital converter - Google Patents

Abstract

The invention relates to a measurement technique and can be used to convert a mean voltage value of a variable voltage into a code. The invention allows to improve the reliability and speed of the device, which is achieved by the fact that the device containing measuring frequency converter 2, frequency subtraction unit 3, key 6, pulse counter 7, reversible pulse counter 11, comparison unit 13, code-frequency converter 12 is inserted . 2 Il. (L

Description

FIG. /

The invention relates to a measurement technique in the range of infrared and sound frequencies and it can be used in the experimental determination of the amplitude-phase frequency characteristics of quadrupoles, ;; in acoustic measurements, research in the field of automatic control and regulation systems, in geophysics, biophysics, acoustics, and oceanology for conversion into a digital code of the average value of an alternating voltage.

The purpose of the invention is to increase the reliability and speed of the converter.

Figure 1 shows the functional diagram of the transformation of bodies; figure 2 - timing charts of his work.

The converter includes an input bus 1, a measuring frequency converter 2, a frequency subtraction unit 3 with inputs 4 and 5, a key 6, a pulse counter 7, the output buses 8 of the converter, inputs 9 and 10 of a reversing counter 11 pulses, a code-frequency converter 12, block 13 management

The timing diagram (Fig. 2) indicates: 14 is the voltage at the input bus 1; 15 - voltage at the output of the measuring frequency converter; 16 is the output voltage of the converter 12; 17 is the output voltage of block 3; 18 - voltage at the outputs of block 13.

The control unit 13 can be made in the form of a standby multivibrator.

In the initial state at i О, the reversible counter 11 and the counter 7 are set to zero. The input voltage U (t), where Uf, and ft are the amplitude and frequency of this voltage, is applied to the input of the device (plot 14 in Fig. 2). Measuring frequency converter 2 transforms the signal U (t) into a frequency-modulated sequence of pulses (plot 15 in Fig. 2) with frequency cJfQt) where OC% vi.y.y.) o is the frequency deviation; Oo and J are the central frequency and slope of the modulation characteristic. The summing input of the reverse counter 1I is outputted at a frequency cxJ (Sit 1,

to the subtracting input is a feedback signal from the output of the converter 12 at a frequency of 0 km, where N is the content of the reversing counter 11; X is the transfer coefficient of converter 12. At t% 0, N is changed in accordance with the equation TdN / c / t + KN cj (5 | f). Its solution, which vanishes, has the form:

N.41

).

 ABOUT.

 5ihQt-2TS (os "t-e

 

-KiliTT

(one

)

The time dependence of the frequency uJ KN of the feedback signal is shown in plot 16 (Fig. 2).

Unit 3 generates a signal with a frequency uW J equal to the modulus of the difference of the frequencies of the signals arriving at its inputs: AU | u) (fJt) -uJV. After transformations we get

Do) - (ojogktg51skh) t

 to

)

30 xsih (si-fc4-qrct glyg

Plot 17A (Lj as a function of time is presented in Fig. 2, the transition component uJ 2hr (-k1 / g) of the frequency AoJ plot and 17 in Fig. 2, the dotted curve kills to the level)) t in time t ((k) and ( and here

J; r, 2 fr51oJK // K +4 is the amplitude of sinusoidal half-waves of the frequency (J of the output signal of the digital frequency at (plot 17 in figure 2 ;.

The numerical estimates of the converter parameters are performed. Let the frequency of the signal being processed Si -, the central frequency and the devi of the frequency of the measuring frequency converter 2 txJp nt

 21Г-10 с and converter transfer coefficient 12 К 4 ТТ с Then uj; 4.44-.10 s-1. It is noted that measurements of the mean voltage of the alternating voltage

produced with an accuracy of less than 0.1%. if (, 05 tJv 2.22-lO c- The last inequality holds for i. 0.53 s.

3

After the time C has elapsed since the measurement system was turned on, the unit 13 forms a gate pulse with a duration (H / S2 equal to the half-period of the signal being processed (plot 18 in Fig. 2). At this time, key 6 opens and passes a packet to the input 7 of the counter pulses with a frequency of AO). At t G + 7G / L, the key 6 is closed and the desired conversion result is formed in the counter 7.

M.

VK - - in- Sl

(3)

With the agreed values in the expression (3) M 1125. The relative error of the measurement result does not exceed 0.1%, to obtain it took the time interval i + / 1.03 s, only slightly exceeding the duration of the converted signal in duration (1 s .

84

Claims (1)

Invention Formula A variable voltage converter into a code containing a measuring frequency converter, the input of which is an input bus, and the output is connected through an serially connected subtraction unit and a key to the impulse counter input (i the outputs of which are output buses, the second key input is connected to the output of the control unit, a reversible pulse counter, the first input of which is combined with the second input block subtraction frequencies, and the second input is connected to the output of the measuring frequency converter, characterized in that, in order to increase the reliability and speed, entered into it a code-frequency converter, the inputs of which are connected to the outputs of the reversible pulse counter, and the output is connected to its first input. 18 Compiled by A.Titov Editor N.Rogulich Tehred t.Dubinchak Proofreader G. Reshetnik Order 1004/60 Circulation 818 Subscription VNIIPI USSR State Committee for inventions and discoveries 113035, Moscow, Zh-35, Raushsk nab., 4/5 Branch PPP Patent, Uzhgorod, Proektna St., 4