SU970633A1 - Amplitude modulator - Google Patents

Description

(5) AMPLITUDE MODULATOR

one

The invention relates to radio engineering and can be used to generate amplitude-modulated signals, for example, in broadband radio transmitting devices.

The amplitude modulator is known, which contains a first controlled attenuator, one input of which is the input of the amplitude modulating signal of the amplitude modulator, a second controlled attenuator connected in series, one input of which is the input of the carrier signal, the frequency of the amplitude modulator, a power coupler and an envelope detector, as well as a differential amplifier.

However, the known amplitude modulator does not provide sufficient stability of the modulation depth coefficient when the output power varies.

The purpose of the invention is to increase the stability of the modulation depth factor.

Claims (1)

The goal is achieved by the fact that in an amplitude modulator containing a forward controlled attenuator, one input of which is an input of a modulating signal of an amplitude modulator, successively connected a second controlled attenuator one input of which is an input of a signal of a carrier frequency of an amplitude modulator, a coupler power and the envelope detector, as well as a differential amplifier, between the output of the envelope detector and the non-inverting input of the differential amplifier are in series connected The first peak detector and the normalizing divider, between the detector output: the envelope and the inverting input of the differential amplifier, is the second peak detector, the second input and the output of the first adjustable attenuator are respectively connected to the output of the differential amplifier and the second input second controlled attenuator. FIG. Figure 1 shows the structural electrical circuit of the proposed device; in fig. 2 - voltage diagrams at the output of the envelope detector. The amplitude modulator contains the first controlled attenuator 1, the second controlled attenuator 2, the response 3 Power, details, the envelope vector k, the first and second peak detectors 5 and 6, the normalizing divider 7, the differential amplifier 8. 8 if the input value is insufficient The modulating signal amplitude modulator also contains a low-frequency power amplifier 9. The amplitude modulator operates as follows: A low frequency modulating signal is fed to the input of the first controlled attenuator 1, which, if necessary, is amplified by the low frequency power amplifier 9 and fed to the input of the second controlled attenuator | aa 2, to the second input of which a carrier signal arrives. The amplitude-modulated signal from its output through the power coupler 3 is supplied to an envelope detector, the output of which receives a signal (Fig. 2). The modulation depth M can be described by the following expression: where K is the proportionality ratio determined by the normalizing divider 7. The signal from the detector (the envelope is fed to the input of the peak detector 5, the output of which receives the signal and, at the output of the peak detector 6 receives the signal where Kli transmission factors. Peak detectors 5 and 6. The signal received from the output of the differential amplifier 8 acts on the first controlled attenuator 1 and changes the value of the modulating signal applied to the input of the second control of my attenuator 2 before the following differential is obtained at the inputs of a differential amplifier:. Then, M K is a constant value. Changing the output power leads to a proportional change in the modulating voltage, which allows the Voltage to automatically maintain a constant depth of amplitude Modulation; Formula of the invention. Amplitude modulator, containing, a first controlled attenuator, one input of which is an input of a modulating signal of an amplitude modulator, serially connected a second controlled attenuator, one the input of which is an input of a carrier signal of an amplitude modulator, a power coupler and an envelope detector, as well as a differential amplifier; distinguishing, in order to increase the stability of the modulation depth factor, between the output of the envelope detector and a non-inverting input the differential amplifier introduced in series the first peak detector and the normalizing divider, between the output of the envelope detector and the inverting input of the differential amplifier introduced the second peak d the detector, while the second input and the output of the first controlled attenuator are connected respectively to the output of the differential amplifier and the second input of the second controlled attenuator. Sources of information taken into account in the examination 1. USSR author's certificate in application N 2828230 / 18-09, cl. H 03 C 1/06, 1979 (prototype). 1 / Fng.g