Electrical Engineering - Re: AM radio: 20 KHz sine-wave modulator signal present on an astronomically-low frequency carrier

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Re: AM radio: 20 KHz sine-wave modulator signal present on an astronomically-low frequency carrier

Karl Uppiano

2007-06-30, 8:25 pm

"Radium" <glucegen1@gmail.com> wrote in message
news:1183251351.057571.13160@i38g2000prf.googlegroups.com...
> On Jun 30, 1:35 pm, j...@specsol.spam.sux.com wrote:
>
>
> Huh?
>
> Usually amplitude of any signal is determined by the power of the
> signal. Power is usually measured in watts.
>
> What SI unit is the amplitude of an AM modulator signal measured in?

For standard broadcast AM, the amplitude of the modulating signal is
expressed as a percentage of the amplitude of the carrier. 100% is defined
as the point where the carrier becomes cut off on the negative modulating
signal excursion. The percentage could be expressed as decibels as well: dB
= 20*log(Vm/Vc), where 0 dB equals 100%. Modulation meters are calibrated in
% and dB. http://www.belar.com/AM/amm3.htm

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