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From vintage tube-based gear, to military surplus, to modern, ultra-efficient FET-based Class E transmitters, Amplitude Modulation (AM) offers the experimenter, homebrewer, and radio restoration buff great opportunities to learn, build, and enjoy radio.
- Low Frequency
The Transatlantic on 2200 Meters—this article has a...
- AM Frequencies
The American Radio Relay League (ARRL) is the national...
- Slow Scan Television
TV on 10 QST April 2001, pp. 68-71 Swap pictures on 10...
- ATV - Fast-Scan Amateur Television
Introduction to Amateur Digital Television Jim Andrews,...
- Space Communication
ARISS News and Information The latest Information about the...
- Antique/Vintage Radio
Bring 'Em Back Alive! QST August 1995, pp. 49-52 Restoring...
- Low Frequency
Amplitude modulation (AM) is a modulation technique used in electronic communication, most commonly for transmitting messages with a radio wave. In amplitude modulation, the amplitude (signal strength) of the wave is varied in proportion to that of the message signal, such as an audio signal.
The idea behind class E is to reduce or eliminate the effects the various capacitances within the MOSFET have on efficiency and operation at high frequencies. The major operational condition is that the MOSFET is only switched (turned on) when there is no voltage across the device.
Amplitude Modulation (AM) is essentially a mixing process where the audio "modulating" signal is mixed with the radio frequency "carrier". The resulting signal actually consists of three distinct components: the carrier, the upper sideband (carrier frequency plus the audio modulating frequency) and the lower sideband (carrier frequency minus ...
13 gru 2017 · In AM transmitters, pulse-width modulation is still king. Pulse Width Modulation (PWM) or Pulse Duration Modulation (PDM) is a technique of converting analog signals into rectangular waveforms. The width of the waveform varies in proportion with the amplitude of the analog signal.
In an AM transmitter, Generation of Amplitude Modulation can be generated at any point after the radio frequency source. As a matter of fact, even a crystal oscillator could be amplitude-modulated, except that this would be an unnecessary interference with its frequency stability.
To produce an amplitude modulated signal, the instantaneous amplitude of a radio frequency carrier wave is varied in direct proportion to that of the modulating signal. The modulating signal carries the required information and often consists of audio data, as in the case of AM radio broadcasts.
