[dba-Tech] Question about Radio technology

AM is amplitude modulation
the amplitude of the transmitter frequency is modulated with the (audio) signal
to be transmitted.
the receiver then uses a rectifier to get the signal back
AM bands are long wave (around 100 to 150 kHz, IIRC), medium wave where you have
most of the radio stations, short wave where you have HAM radio and stations
that sent to very high distances. Short wave is used for sending around the
world because the short wave is reflected in the higher level of the atmosphere,
then again on the earth and back up, thus can trabel around the world, while the
lower frequencies go straight only.
FM  is frequency modulation, that is, the signal is used to change the frequency
of the transmitter while the amplitude stays constant. therefore amplitude
changes do not influence the audio signal, and the received audio signal is
independent of most noise 8which would influence the amplitude only.

dont know whether this was clear enough. otherwise feel free to ask

Lembit Soobik

----- Original Message ----- 
From: "Arthur Fuller" <artful at rogers.com>
To: "'Discussion of Hardware and Software issues'"
<dba-tech at databaseadvisors.com>
Sent: Monday, November 24, 2003 9:37 PM
Subject: [dba-Tech] Question about Radio technology


> Someone asked me to explain the difference between AM, FM and short wave
> and I suddenly realized that I have huge gaps in my alleged knowledge of
> same. Can someone point me to a net-splanation or supply one?
>
> TIA,
> Arthur
>
>
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