SU1453590A1 - Device for determining mean value of signals - Google Patents

Abstract

This invention relates to a measurement technique. The purpose of the invention is to increase the accuracy of determining the average values of signals. CuHxpoMuaatfun) e input device contains switches 1,2 and 3, resistors 5.4 and 6, capacitor 8, operational amplifier 10, charge-discharge circuit (SFC) 12 and control unit 13. Improving the accuracy of measurement of average values of the studied There are no signals in this device due to the absence of an integrator of time and a divider, and therefore the absence of an error in converting the time interval to an analog value and the absence of an error in dividing analog values. The apparatus is characterized by the introduction of a resistor 6 and a SAR 12, consisting of a resistor 7, a capacitor 9 and an inductor 11. 1 hp f-ly. 2 Il. c & (L

Description

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

The purpose of the invention is to increase the accuracy of determining the average values of 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 and third switches 1-3, the first, second, third and fourth resistors 4-7, the first and second capacitors 8 and 9, the operational amplifier 10, the inductor 11, the charge base bit circuit 12 and control unit 13.

The device for determining the average values of the signals works as follows.

In the initial state at the input of the Synchronization device to determine the average values of the signals, there is a voltage of zero. level, and at the input Reset - the voltage of a logical unit. At the same time, the first and second outputs of the control unit 13 are set to voltage of the zero level and the level of the logical unit, as a result, the key 2 is in the neutral position, at which its output is not connected to any of its inputs, but the keys 1 and 3 are closed, the capacitor 8 is discharged, and the output voltage of the device for determining the average values of the signals is absent.

At time t, the input voltage Reset changes from a logical one to a logical zero. In this case, the key is opened.

At the moment t, the control pulse is fed to the synchronization input (Fig. 2b), which is fed to the first input of control unit 13 and to the first control input of key 2. During the operation of the control pulse of duration T tj - t ,, the key 2 switches from neutral to the first operating position at which the output of the key 2 closes with its first input.

From the moment of time t (the input signal V, (fig.2a) goes through the resistor 4 and the switch 2 to the input of the operational amplifier 10, the output voltage of which varies according to the law

i, 4t

where R is the resistance of the first resistor 4;

C - the capacity of the first capacitor 8.

At the same time through the coil 11 inductance current flows (Fig.2e)

t

; c, (cook;) j

where R and RJ are the resistances of resistors 6 and 7.

At time t, the control is terminated (its pulse at the synchronization input (Fig. 2b), and switch 2 switches to the neutral position. The voltage at the output of operational amplifier 10 during the averaging time T V, ---- (V dt co - to, L, J about

wound unchanged.

The current in the inductance coil 11 is equal to

t

h R7c :() J

the voltage on the capacitor 9 is equal to the voltage on the resistor 7:

cr u rv

After time cTja at time t, tj - chld lok 13 control generates at the first output a pulse of the level of logical unit (fig.2g), which is fed to the second control input of key 2. The pulse duration is equal to CT C where K is the proportionality factor. In this case, the key 2. switches to the second operating position.

At the second output of the control unit 13 at time t, the voltage pulse of the level of the logical unit

CO, Cf, "L

D

-frequency, initial phase and damping factor of the oscillations of the loop current;

- coefficient of proportionality, defined by the expression

R

G7

 -, (

+ R L) L

k, + 1,

where L is the inductance of inductance coil 11.

The currents (. And 1, arriving at the input of the operational amplifier 10, are summed, the voltage at the output of the operational amplifier 10 changing from time tj from V, as t t

by law t

and, V. - - f (1e + IK) dt,

-4 J tj

 I

approximating hyperbolic function (fig.2e)

and,

where bi. - scale factor.

The parameters of the elements of the device to determine the average

where a

V C-2. arctg (

J

different from the mean value of the function

five

V

wed

with an error determined by the approximation error.

From the moment of time 1c at the output 0 of the device for determining the average values of the signals, there is a voltage proportional to the average value of the input signal during the averaging time T.

If it is necessary to single out the mean value of the signal for another averaging time or to conduct a new cycle of averaging the signal in another interval5

At the time, the voltage on the capacitor 8 is reset, which is realized by applying to the Reset input at the time tc a voltage pulse of the level of the logical unit (Fig.26), which, having entered the control input of the key 1, closes it for the duration of the pulse. At the same time, the output voltage drops to zero, i .e. initial zero conditions are entered to determine the average value of the other signal.

Improving the accuracy of measuring the average values of the studied signals in the proposed device is due to the absence of an integrator of time and a divider, and therefore, the absence of an error in converting the time interval to an analog value and the absence of an error dividing analog values.

Claims (2)

1. A device for determining average values of signals containing an operational amplifier with a capacitor in a negative feedback circuit, in parallel with which a first switch is connected, between the input of the device for determining average values of signals and the inverting input of an operational amplifier 535906 connected in series the first resistor and the second switch, as well as in series connected the second resistor and the third, the key, the control unit, the inputs and outputs of which are connected to the corresponding control inputs of the first, second and third keys, different 10 by the fact that, in order to increase the accuracy, the third resistor and the charge of the discharge circuit are introduced, and the second normal output of the second resistor and the charge output of the discharge discharge circuit are connected to the third normally open output of the second switch which is connected to the second output of the third key, the first output of which through the third resistor is connected to the output an operational amplifier and is the output of the device for determining the average values of the signals. 2. The device according to claim 1, in which the charge-discharge circuit is made in the form of series-connected second capacitor and inductance coil, the first terminals of which are connected to the first output of the fourth resistor, the second output of which is the input of the charge-discharge circuit, the output of which is the second output of the second capacitor, and the second output of the catutaki inductance is connected to the common bus. VNShShN Order 7301/55 Productive-polngr. pr-tie, Uzhgorod, st. Project, 4 Circulation 879 Subscription