SU785946A1 - Device for detecting amplitude-modulated signals - Google Patents

Description

The invention relates to radio engineering and can be used in automatic control systems, in servo and measuring systems for converting amplitude-modulated (AM) oscillations of alternating voltage to direct voltage or to low-frequency voltage.

A device for detecting amplitude-modulated Yu signals containing a phase-sensitive rectifier and a division unit, as well as a reference signal generator, the output of which is connected to the control input 15 of the phase-sensitive rectifier JjfJ.

However, the known device has insufficient accuracy of detection.

The purpose of the invention is to increase the accuracy of detection.

For this, in a device for detecting amplitude-modulated signals containing a phase-sensitive rectifier 25 series dividing unit and a division unit, as well as a reference signal generator, the output of which is connected to the control input of the phase-sensitive rectifier, between the output of the reference signal generator and 30 the second input of the division unit a half-wave rectifier, and the division block contains an operational amplifier, in the negative feedback circuit of which an analog multiplier is connected. wherein the inverting input of the operational amplifier is the first input, and the second input of the analog multiplier is the second input of the division unit.

In FIG. 1 is a structural electrical diagram of the proposed device, * in FIG. 2 is a timing diagram explaining its operation.

The device comprises a sensor 1 of a measured value, a reference signal generator 2, a phase-sensitive rectifier 3, a half-wave rectifier 4, and a division unit 5, including an analog multiplier 6 and an operational amplifier 7.

The device operates as follows.

The input signal 1C = A (t) sino> t is converted to a signal U ₂ = A (t) / S i ncjt / after dividing it by a signal Uj = / SinUt / U ₀ we get (J ₂ Α (1) ί5ίηωί / АН) _n where Uq is a constant coefficient,

Qt R, (R = 0,, 1, 2...).

The amplitude-modulated oscillation from the output of the sensor 1 (see Fig. 2a) through the rectifier 3 (see Fig. 2,6) is supplied to the non-inverting input _ of the amplifier 7, and the inverting input ^{3 of} which is supplied by the voltage from the rectifier 4, multiplied with the output voltage amplifier 7. The input of the rectifier 4 (see Fig. 2d) receives voltage from the generator 2 (see Fig. 2c) '^

As a result, the voltage at the output of amplifier 7 (see Fig. 2e) is equal to Ndr | x = £ A (t) / S ΐ Π (ύt / ”U breathe Ujj / S 1 nwt / 3 K” (2) where the voltage of the output signal ;

K is the gain of the amplifier 7.

From here

KA (i) / s <ncjj I Ali) / s <ncj-t / 20 ах 4 + Κ · υ _ο ) β <ηωί / · 4 / Κ + υ _ο ) ε <ηωί / as К ->3; 0.

; As a result, the signal U 2 is divided by the signal Uj in coot 25 expression (1) and n

. ... ^Bbix ~ and ₀ ;

Due to the uncertainty of the division operation at the points where Sin60t = 0, 30

t. i.e., at 6ot = ¾ R, the output voltage has insignificant ripples (see Fig. 2e), which decrease with increasing fission accuracy.

Thus, the proposed device, in comparison with the known one, allows one to isolate the envelope from the AM signal with lower equipment costs and reduce its phase shift relative to the real envelope without increasing the level of the reference voltage ripple.

Claims (2)

coefficient, where DO is the perennial Wt R, (R 0, J. 2 ...). The amplitude-modulated oscillation from the output of sensor 1 (see Fig. 2 through rectifier 3 (see Fig. 2.6) enters the non-inverting input of amplifier 7, the inverting input of which receives voltage from rectifier 4 multiplied by the output voltage Amplifier 7. At the input of spreader 4 (see Fig. 2d), the voltage comes from generator 2 (see Fig. As a result, the voltage at the output of amplifier 7 (see Fig. 2e) is equal to U8bix LA (t ) / S i nwt / - and BbixUo / s 1 ncot / 3 K, (where OAH is the voltage of the output signal K is the gain factor of the amplifier 7. Hence k-AU) / 5 ncJ4; / AW / s nwi / Bbix- + K.Uofs nco-t / l / K + UQ s n60t / with k-8 J. -y- - 0.; as a result, the signal LJ 2 is divided by the signal U 3 in accordance with the expression (1) and. A (t). .... Due to the uncertainty of the division operation in points, where SinCOt is 0, i.e., at CotL R, the output voltage has slight pulsations (see Fig. 2e), which decrease by increasing the accuracy of the division. Thus, the proposed device is less expensive than the known n equip the AM signal from the envelope and reduce its phase shift relative to the real envelope without increasing the ripple level of the reference voltage Wives Claim 1. A device for detecting amplitude-modulated signals, comprising a series-connected phase-sensitive rectifier and a dividing unit, as well as a reference signal generator, the output of which is connected to a control-type input of a phase-sensitive rectifier, characterized by that. That, in order to increase the detection accuracy, a full-wave rectifier is connected between the output of the reference signal generator and the second input of the division unit. 2. The device according to claim 1, wherein the division unit contains an operational amplifier, in the negative feedback circuit of which an analog multiplier is included, in which the non-inverting input of the operational amplifier is the first input, and the second input of the analog multiplier . Sources of information taken into account in the examination 1. Pipin V.I. On detection of signsshov, the duration of which is comparable with the period of the carrier oscillation. WORKS of the Gorky Polytechnic Institute, 1969, vol. 25, No. 6, p. 96-98 (prototype). breathing