Modern AM Broadcast transmitters are pulse width modulated with the
rated carrier power at 40% width of the pulses.
Negative modulation moves the pulse width towards zero pulse width
( carrier cut-off )
Positive modulation moves the pulse width towards full pulse width.
80% pulse width = 100% modulation or 4 x carrier power.
100% pulse width = 125% Positive modulation or 5 x carrier power.
Conventional Plate Modulation using audio transformers and Pulse Width
Modulation ( sometimes referred to as Pulse Duration Modulation or PDM )
looks identical on an oscilloscope and is detected identically with receivers.
Don W4DNR
DonR
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