SU503250A1 - Apparatus for calculating the logarithm difference of two electrical signals - Google Patents

Description

logarithm I. The voltage at the output of the logarithm in the time interval is determined by the formula

f / out 1.1 t out 0.1 + - / Cl 1n (/ C2 vf / BX. L), (1)

where UBX.I is the voltage at the first input of the device;

.i.i is the output voltage of the logarithm 1, acting in the time interval,

Unax.o.i is the voltage at the output of the logarithm 1 in the absence of voltage at the input of the logarithm; Ki is the transformation coefficient of the logarithm;

K2 is the key transfer coefficient 2. The voltage UBUX.I.J through the controlled attenuator 9, the key 5 and the integrator 10 is fed to the first input of the differential amplifier 13. The input voltage is determined by the formula

t in. 1.1.13 Kyu Ks kykh. 0. /C-ln(/C2f/BX.l),(2)

where / Xu is the integrator conversion factor;

/ Cs-key transfer ratio 5;

KE - transfer coefficient of controlled attenuator 9.

At time ti, keys 2 and 5 are turned off, and at time t2, keys 3 and 6 are turned on. Input voltage C / in 2 is through key 3, logarithm 1, controlled attenuator 9, key 6 and integrator 11 is fed to the second input differential amplifier 13 and to the third input of the additional amplifier 14. The magnitude of the voltage acting at the inputs of the amplifiers at times 2 + 3 is determined by the formula

 in 2.2.13 in. 2.1.14 - / Si KB KdW out. 0.1 +

+ ./С-1п(/Сз-1/вх.2) ,(3)

where Kp is the conversion factor of the integrator 11;

KV - key transfer ratio 6; Кз - key transfer ratio 3; UeK.2 - voltage at the second input of the device.

At time s, keys 3 and b are turned off, and at time t, keys 4 and 7 are turned on. The input voltage t / Bx.2 is through uncontrolled attenuator 8, key 4, logarithm 1, controllable attenuator 9, key 7 and integrator 12 is supplied to the first input of the additional amplifier 14. The voltage acting on the second input of the amplifier 14 at the time is determined by the formula

 in 2.2.14 Kl2 K2 Ke {f / out. 0.1 +

+ /С-1п(/С4--С/вх.2), (4)

where Ki2 is the conversion factor of integrator 12;

./Str-key transfer ratio 7;

./(4 key transfer ratio 4;

a is the transfer coefficient of the uncontrolled attenuator 8.

At time ts, keys 4 and 7 are disabled, and at time e, keys 2 and 5 are turned on again, and so on.

The second input of the additional amplifier 14 receives the reference voltage LonOT of a highly stable voltage source 15. The voltage at the output of the difference amplifier 13 is determined by the formula

and out. 13 and 1.1 13 Kl.13 - and in. 2.2.13 K: 2.3 10 out. 0.1 +

+ (K2-i.,) - to 2.13 Ki Kb-Ke U out. 0.1 +

+ /C.1p (2), (5)

where k

mz; , - the transfer coefficients of the amplifier in the first and second

input, respectively. The device circuit is configured so that the equalities hold

.13 Kyu Ks K2; 13 Kll Kb Kl3, K2 KS

Then the formula (5) takes the form. 13 Ki3 - / Cg- CClnt / Bx 1 -lnf / Bx.2) (6)

Two attenuators controlled by 9 and unmanaged 8, keys 4 and 7, integrator 12, additional amplifier 14 and control source for controlling the controlled attenuator 9 change it so that the algebraic sum of the input signals of additional amplifier 14 is equal

zero, i.e. f / BX. 2.1.14- fJ in. 2.2.14 + op. About (7) or

Kll KB-Ke U out. 0.1 + К 1п (/ Сз - U out 2) 1 - - / Cl2 Cr 9 t / VY.H. 0.1 +: In (L: 4 a f / in 2) 1+ + op. 0 (8)

The automatic gain control system is adjusted so that the equalities

CP Ki Ki2 - Ki

KS, Kt

In this case, the expression (8) takes the form

Kp-Kb-K.-K 1pa 0

and,

or

J / on.

(9)

K9-K

Кц Кб In а

in formula (6), according to (9)

Substitute the formula of the ray

Woo "

(lnf / 3x. 1 and out. 13 K2-IZ In and -lnf / BX-.2) (Yu)

Thus, introducing additional elements into the device eliminates the dependence of the output voltage of the amplifier 13 on the magnitude of the transformation coefficient of the logarithm and improves the accuracy of measuring the difference between the logarithms of the two electrical signals.

Claims (1)

Apparatus of the invention The first and second switches are connected to the corresponding inputs of the device, an amplifier whose inputs are connected to the outputs of the integrators, the inputs of which are connected respectively to the outputs of the third and fourth keys, whose inputs are combined, a generator, the outputs of which are connected to the control inputs of the keys, characterized in that in order to increase accuracy, keys, an integrator, an amplifier, a source of reference voltage and elements with a constant and controlled transmission coefficient, the input of the first of which are connected to one of input devices, and output - with additional input of the first switch, whose output is connected to the input logarifmatora. the output of which is connected to the element with a yi transmission coefficient, the output of which is connected to the inputs of the third and fourth keys and the input of the second additional key, the output of which is connected to an additional integrator, the output of which is connected to the first input of an additional amplifier the third input is output the integrator corresponding to the fourth key, and the output of the additional amplifier is connected to the control input of the element with a controlled gain ratio, the control inputs of the additional keys are connected to the outputs of the generator.