SU1457145A1 - Device for determining mean values of signals - Google Patents

Abstract

This invention relates to a measurement technique. The purpose of the invention is to improve the accuracy of determining the average values of signals. The device contains keys 1–4, resistors 5 and 6, capacitor-8, operational amplifier 10, charge-discharge circuits (SAM) 11 and 12, control unit 13 and large-scale amplifier 14. Peripheral accuracy of measuring average values of the signal under investigation in this device due to the absence of an integrator of time and a divider in it, and consequently, the absence of an error in converting the time interval into an analog value and the error, dividing analog values. A device according to Clause 1. F-ly is characterized by the introduction of 11 and 11. 12 and a large-scale amplifier 14. The device according to claim 2 of the f-ly is characterized by the performance of the ЗРЦ П and 12, each of which consists of a resistor 7 and a capacitor 9. 1 Cp, f-ly, 2 ill. i (L

Description

II-j- 1

The invention relates to a measurement technique and can be used in technical diagnostics devices.

The purpose of the invention is to increase the precision of the mean values of the signals.

Fig. 1 is a circuit diagram of an apparatus for determining average values of signals; Fig. 2 shows the time diagrams of the stresses that explain its operation.

The device for determining the average values of the signals contains the first, second, third, and fourth switches 1–4, the first, second, third, third resistors 5–7, the first and second capacitors 8 and 9, the operational amplifier 10, the first

second and second charge-discharge circuits

11 and 12, control unit 13 and scale amplifier 14,

The device works as follows

In the initial state, the device Synchronization has a zero voltage level at the input, and a logical one level voltage at the Reset input. At the same time, the outputs of the control unit 13 are set to zero level voltage and the second key 2 is in the neutral position, in which its output is not connected to one of its inputs. The first key 1 is closed, first the capacitor 8 is discharged and the voltage on the device code is zero,

At the moment of time tv the input voltage Reset changes from a logical unit to a logical zero. In this case, the key 1 opens,

At time t, a control pulse (FIG. 2b) is fed to the Synchronization input, which is fed to the first input of control unit 13, to the first control input of key 2 and the control inputs of keys 3 and 4. During the control pulse duration of time T tt ,, key 2 at time t

switches from the neutral position to the first operating position, at which the output of the key 2 closes with its first input, and the keys 3 and 4 close, connecting the inputs of the back of the discharge discharge circuits 11 and 12 and their capacitors 9 to the output of the amplifier 10, the voltage on the encoder 9 of the second charge-rachrdnaya circuit 12 is determined by the output voltage of the operational amplifier 10 and the transfer coefficient M of the scale amplifier 14,

From the moment t on time, the input signal Vj (FIG. 2a) is fed through a resistor 5 and a switch 2 to the inverting input of the operational amplifier 10, the output voltage of which varies according to the expression t, -T

-i

 ;, v.dt.

V

-RTC7

(I)

five

0

five

thirty

35

40

45 50

55

where R, is the resistance value

the first resistor; C - the value of the capacity of the first

capacitor 8;

T - time counted from time t ,.

At the end of the forward voltage pulse at the synchronization input at time t, key 2 switches to the neutral position, a-keys 3 and 4 open. In this case, the voltage at the output of the operational amplifier 10 is described by the expression (1) and remains unchanged (FIG. 2d), as is the voltage on the charge-discharge capacitors 9 of the discharge circuits 11 and 12, equal to V ,, V ,; V,

 ,,

After time C d, the control unit 13 generates at the output a voltage pulse of a logical unit of duration K-T t 4-- tJ (where K is a scale factor, which is selected from the condition of the device’s speed), which goes to the second control input of key 2 and switches from the moment of time tj from neutral to the second working position (FIG. 2d),

The capacitors 8 and 9, connected to the corresponding resistors 6 and 7 to the input of the operational amplifier 10, are discharged exponentially, and the currents in their circuits (Fig. 2e) are described by the expressions

-.-- r- P - b: - b

a - - "p - 1-c; (. b

. (.

where is r,

R.

WITH.

Currents t, t.

resistance values of the resistors 6 and 7; capacitor values of capacitors 8 and 9,

Cj, entering the input of the operational amplifier 1P, is summed up and the voltage at the output of the operational amplifier 10, equal to the voltage on the capacitor 8, changes from time t from V to t

 t by law

and, v, -4- (

.N

WITH,

I1

) dt

  - -k 5Н-, - ---- ill

,

t-t;

) +

)

approximates a hyperbolic function and d - -, where d is a masgabate factor.

The parameters of the elements are chosen in such a way that the expression (2) describes a hyperbolic relationship with a minimum error, Then the voltage U, at the output of the device to determine the average values of the signals at the time t of the end of the pulse, is proportional to the average value of the input signal over time averaging T and differs

R

from the mean of the function

 -pf, - J with the termination determined by the approximation immersion.

If it is necessary to select the average value of the signal for another averaging time or to conduct a new averaging cycle of the input signal in a different time interval, the voltage on the capacitor 8 is reset, which is realized by applying to the reset bus (Reset input) a voltage pulse of the logic level level. t "(Fig.26), which closes the key 1 for the duration of its action. In this case, the voltage on the capacitor 8 and on the output of the device for determining the average values of the signals drops to zero, i.e. the initial zero yields are entered. media detection

57

ten

15

20

25

45

40

50

55

45

its value is another signal.

The increase in the accuracy of measurement of the average values of the signal under study in the proposed device is due to the absence of a time integrator and a divider in it, and consequently, the lack of error in converting the time interval to an analog value and the absence of an error in dividing the analog values.

Claims (2)

Invention Formula ). A device for determining the average values of signals containing an operational amplifier with a capacitor in the negative feedback circuit connected to the first switch, between the input of the device for determining the average values of the signals and the inverting input of the operational amplifier are connected in series with the first resistor and second switch and in series the connected second resistor and the third key, the fourth key, the control unit, the inputs and outputs of which are connected to the corresponding inputs y The first, third and fourth keys, characterized in that, in order to increase accuracy, a large-scale amplifier and two charge-discharge circuits are introduced, the inputs of which are connected to the secondary terminals of the third and fourth keys, the first terminal of the fourth key is connected through a large-scale amplifier the first output of the third key, the output of the operational amplifier and is the output of the device for determining the average values of the signals, and the first output of the second cutter is connected to the third normally open output of the second key - tori and outputs of the first and second charge-discharge circuits. 2. The device according to claim. Characterized in that the charge-discharge circuits are made in the form of serially connected third resistor and second capacitor, the first terminals of which are the input of the charge-discharge circuit, the output of which is the second output of the third resistor, and the second terminal of the second capacitor is connected to the common poultry. ij tnti