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Amplitude Modulators

Ernst Erb Otmar Jung 
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Papers » Basic principles of radio technique » Amplitude Modulators
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Dietmar Rudolph
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Amplitude Modulators


The earliest modulation for audio transmission via radio is amplitude modulation (AM). First experiments with AM were done without tube transmitters. In those times, alternators and arc transmitters were used.

In this paper examples of amplitude modulation from early techniques to modern applications of digital modulation is covered. Interesting to notice how early solutions, formerly without great relevance, now become important applications.


Modulating a carrier
            ideal AM modulator; AM time function and spectrum; modulation degree

Transmitter types

Alternators; Fessenden; Goldschmidt; external frequency multiplier; Lorenz transmitter Munich

            Poulsen arc transmitter

           Single stage transmitters; absorption modulation; grid DC modulation

Multi stage transmitters; grid modulator; Heising modulator; anode-B-modulator; modulator with series tube; pre stage modulator

           Controlled carrier; AM peak and mean power; controlled carrier modulator

           Doherty modulator

           Chireix modulator

High efficiency transmitters

          Switched type modulators; system Telefunken; system Marconi; switched power supply

Semiconductor transmitters

          H-bridge; combining H-bridge modules; PDM modules

          Switched H-bridge modules; spectral behavior

Modulator for digital modulation

EER techniques; digital signals; bandwidth of amplitude and phase signals; AM transmitter using EER techniques


Contribution in German

Text in German for automatic translation on request.