SU1478144A1 - Pulse number meter in two alternating pulse trains - Google Patents

Abstract

The invention relates to a measurement technique and can be used in apparatus for examining media, objects and materials by pulsed methods. The purpose of the invention is to improve the measurement accuracy. A pulse number ratio meter in two alternating pulse series contains a single vibrator 2, an analog signal switch 7, an inverting integrator 9. Introduction of differentiating element 1, rectifier 3, delay element 4, pulse counter 5, DC voltage source 6, digital-analog converter 8 and sampling and storage element 10 allows to reduce temporal and temperature instabilities of the scale factor of the meter, which is proportional only to the value of the output voltage of source 6. 1 Il.

Description

The invention relates to measuring equipment and can be used in equipment for the study of media, objects and materials by pulsed methods.

The purpose of the invention is improving the accuracy of measurements.

On Fig, 1 presents a structural diagram of a device; on Fig, 2 timing diagrams explaining his work about

The meter contains a differentiating element 1, a single vibrator 2, a rectifier 3, a delay element 4, a pulse counter 5, a DC voltage source 6, a switch 7 of analog signals, a digital-to-analog converter (DAC) 8, an inverting integrator 9, and a sampling and storage element 10.

The clock input of the counter 5 is connected to the information input 11 of the device. The input of the differentiating element 1, the start input of the one-shot 2 and the control input of the switch 7 are combined with the switching input 12 of the device, and the output of the differentiating element 1 is connected to the input of the rectifier 3, the output of which is connected to the input of the delay element 4 and the clock input of the DAC 8, to the output of the element 4 the delay is connected to the zero input of the counter 5, the information outputs of which are connected to the corresponding inputs of the DAC 8, the output of the reference voltage source 6 is connected to the first analog input of the switch 7, the second analog input One of which is combined with the output of the sample and storage element 10 and the device output 13 о The output of the switch 7 is connected to the input of the reference voltage of the DAC 8, the output of which is connected to the input of the integrator 9, The analog input of the sample 10 of the storage storage, the control input of which is connected to the output of the integrator 9 connected to the output of the one-shot 2,

The device calculates the ratio of estimates of mathematical expectations of two random discrete processes [n ,; , n _t ; , i £ A = 0,1,2,3,0. (n ₄ ; and η ₂ · - ie the values of the number of pulses of the first and second series, respectively) on the interval of their quasistationarity and works as follows.

Let pulse information flow to the information input 11 (Fig. 2a), and commutation pulses to the switching input 12 (Fig. 2b), and when the first series of pulses appears at the information input 11, at the switching input 12 there is a potential of a logical unit that opens the first the channel of the switch 7, and when the second series appears, a potential of logical zero is applied to the switching input 12, opening the second channel of the switch 7

The number of pulses n _x ; and n ₂ ; the first and second series are converted by counter 5 into binary numbers Ν _υ · and Ν ₂ ; which are alternately fed to the digital inputs of the DAC 8, The pulse input of the DAC 8 from the output of the rectifier 3 receives a pulse stream (Fig. 2e), consisting of dedicated trailing and leading edges of the switching pulses. 0 ”counter 5, R result, at the end of each series, the number Ν ^; , Ν ^ · are written one by one to the input register of DAC 8, and counter 5 is reset. Thus, during the action of the first and second series are input to the reference voltage E _d respectively and the output voltage meter, the output of DAC 8 alternately appear voltage UJ = E _{0 tsDGT} K and U * =, where R _CDP -:

DAC conversion coefficient 8,

Under the action of voltage U; storage capacitor 14 of the integrator 9 over time T / 2. (FIG. 26) receives a charge _ Ko 'Ktsdpt __, where R is the resistance of the resistor 15 of the integrator 9, and in the second half of the period of the switching pulses, the storage capacitor 14 is discharged by current

those. charge is removed from it

The total charge reported to the storage capacitor 14 over time

Lch: - <1; - <1; - rear LVh - "h-VJ ^(|) . Under the action of pulses (Fig.2c) from the output of a single-shot 2, the output voltage of the inverting integrator after recording ix of the first and second series is transferred to the sampling and storage element.

Further, the described process is repeated many times.

The value of the output parameter U (i) is found by solving equation (1) for the average values of N, and under the initial condition U (0) = U _o , As a result,

U (i) = E _o L1- [1 - W (i)] +

2 .. + U _o w (i),.

where W (i) = (lK _Mn N _i; T / 2RC) is the weight function;

C is the capacity of the storage capacitor 14.

Under the stability condition / W (i =!) / <!

output voltage

U (= o) - E. - »1- = E _o -b-, (2)

those. linearly depends on the ratio of the average values of the number of pulses in two pulse series.

From the expression (2) it follows that the scale factor of the measurement is specified only by the value E _{о of the} constant voltage source 6 and does not depend on the parameters included in the meter of individual elements. Therefore, the proposed meter in comparison with the known device has a higher measurement accuracy.

Claims (1)

Claim The meter of the ratio of the number of pulses in two alternating pulse series, containing a single vibrator and a switch of analog signals, the control input of which is combined with the input of a single vibrator and a switching input of the meter, as well as an inverting integrator, characterized in that, in order to increase the accuracy of measurements, series-connected differentiating element, rectifier, digital-to-analog converter, the output of which is connected to the input of the inverting integrator, as well as the delay element, counter pulses, a sampling and storage element and a constant voltage source, the output of which through the analog signal switch is connected to the reference voltage input of the digital-to-analog converter, the output of the inverting integrator through the sampling and storage element is combined with the meter output and the second input of the analog signal switch, the rectifier output through the delay element connected to the installation input at 0 ”pulse counter, the clock input of which is the information input of the meter, and the information outputs the pulse counter is connected to the information inputs of the digital-to-analog converter, the output of the single-vibrator is connected to the control input of the sampling and storage element, and the input of the single-vibrator is combined with the input of the differentiating element.