SU1665517A1 - Amplitude-modulated signal transmitter - Google Patents

Abstract

The invention relates to radio engineering. The purpose of the invention is to increase the transmitter efficiency. The latter contains a pathogen 1, key push-pull amplifiers 2 and 3, an output band-pass filter 4, a power supply 5 of the power supply, a pulse-width modulator 6, and elements 7 and 8 of coincidence. The goal is achieved by reducing the number of transformations in the transmitter, in which the efficiency is determined mainly by the efficiency of amplifiers 2 and 3. 1 sludge.

Description

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The invention relates to radio engineering, is intended for highly efficient generation of amplitude modulated (AM) signals at a high power level, and can be used as broadcast and communication transmitters.

The aim of the invention is to increase efficiency.

The drawing shows a structural electrical circuit of a transmitter of amplitude-modulated (AM) signals.

The AM signal transmitter contains the exciter 1, the first 2 and the second 3 key push-pull amplifiers, the output band-pass filter 4, the power supply 5, the pulse-width modulator (PWM) 6, the first 7 and the second 8 match elements. The first key push-pull amplifier 2 contains the first 2h and second 2a power transistors and diodes 2z and 24. The second key push-pull amplifier 3 contains the first 3i and the second 32 power transistors and diodes Z3 and 34.

The AM signal transmitter operates as follows.

The causative agent 1 generates at its outputs a direct and inverse carrier frequency signals of the square wave type. PWM 6 converts the input low-frequency signal into a pulse train with pulse-width modulation at the clock frequency. The output voltage of the exciter 1 switches the first key push-pull amplifier 2, as a result of which a meander type voltage is applied to its output, which is applied to one of the inputs output band-pass filter 4. The input modulating effect U is fed to the input of PWM 6, as a result of which tn pulses are generated at its output, the duration of which is proportional to U. PWM 6 pulses are on the interval tn unlock the first 7 and second 8 coincidence elements, as a result of which, for each of the pulses at the outputs of the first and second elements of the coincidence, there are signals that repeat the corresponding signals at the outputs of the driver 1. In the absence of PWM pulses 6 at the outputs of the first 7 and second 8 the voltage matching blocks are zero and the signals to the inputs of the second key push-pull amplifier 3 are not received. Thus, during the presence of PWM pulses, 6 at the output of the second key push-pull amplifier 3 is formed as a result of switching its transistors, the voltage 1) of the square-wave type, the antiphase voltage Ua at the output of the first key push-pull amplifier, resulting in

interval tn to the input of the output bandpass filter 4 applied pulse sequence of double amplitude with respect to the amplitudes at the outputs of the first 2

and second 3 key push-pull amplifiers. As a result, a sinusoidal current flows through the output bandpass filter 4, the amplitude of which increases in accordance with its time constant (bandwidth). On the interval of pause tn, the input current of the output bandpass filter 4 is closed for one half-wave carrier through the open transistor 2i and diode G3, and the other half-wave is open

5, the transistor 22 and the diode 34. As a result, at the output of the second key push-pull amplifier 3, a voltage Kz is formed in the interval of pauses, which almost coincides with the voltage U2 and, therefore,

There is no voltage at the input of the output bandpass filter 4. Therefore, the current in the interval pauses decreases. Thus, the amplitude of the output current is formed in proportion to tn, and consequently,

5 to the magnitude of the modulating signal U. Radio pulses are applied to the input of the output bandpass filter 4, the duration of which is determined by the PWM law. By reducing the number of transformations by

In comparison with the known devices, the efficiency of the AM transmitter signals is mainly determined only by the efficiency of the first 2 and second 3 key push-pull amplifiers and therefore increases. Output bandwidth

5, the filter 4 is tuned to the carrier frequency and g also serves to suppress both side and out-of-band spectral components of the pulse voltage applied to its input. Power source 5

0 power supply is a constant voltage source of required power.

Claims (1)

Claims of the Transmitter Amplitude Modulated 5 signals, containing the first key push-pull amplifier, the second key push-pull amplifier, pulse-width modulator, exciter, power source, the output of which is connected to the inputs 0 power supply of the first and second key push-pull amplifiers, the outputs of which are connected to the corresponding inputs of the output bandpass filter, while the direct and inverse outputs of the exciter are connected respectively to the direct and inverse inputs of the first key push-pull amplifier, characterized in that to increase the efficiency, the first and second elements of the match are introduced, the first inputs of which are connected to the output5h. 16655176 do pulse width modulator, impurity, and the outputs of the first and second In this case, the second inputs of the first and second coincidence elements are connected to coincidence matches connected to inverse and direct inputs, respectively. direct and inverse outputs of the second key push-pull amplifier.