Mr. Gassama,

I’d like to differ with you on the following
statement: “All FM transmissions are digital”.
Frequency Modulation (FM), Amplitude Modulation (AM),
and Phase Modulation (PM) are only used in the analog
world. In digital transmission, they are referred to
as FSK, ASK, and PSK respectively. The principle of
Frequency Shift Keying (FSK), Amplitude Shift Keying,
and Phase Shift Keying is to convert a digital signal
into an analog signal so that the digital bit stream
can be effectively transported over and analog system,
such as the airlink of a radio or a cellular network.


Mr. Njie,

Here is some information on AM and FM. I hope this
helps.

Amplitude Modulation: The amplitude of the
carrier/transporting signal is modulated or changed
according to the magnitude of the message signal. For
example, if you raise your voice over the phone, the
amplitude of the carrier signal will rise accordingly.
So the loader you speaker, the larger the amplitude of
the carrier signal.

Frequency Modulation: The frequency of the
carrier/transporting signal is modulated or changed
according to the size of the message signal.

Here are some advantages of FM over AM:

1.Better output signal or less interference, thus,
better voice quality.

2.Smaller interference between neighboring stations.
3.Less radiated power.

4.More capacity (users) in the case of cellular or PCS
networks.


Disadvantages of FM over AM:

1.More bandwidth.

2.Very expensive because of the use of complex
receivers, transmitters, and filters.


Ms. Astrid,

I think the word digital is incorrectly used. If that
is not the case, then “Gambians will now have to have
a special digital receiver”. From what I understand,
no known ‘digital radio’ station is commercially
operating in the U.S.

Do you wonder what happens if you try to use your
regular AM/FM analog receiver to tune to a ‘digital
radio’ station? Well, you will experience very
unpleasant beeps and buzzes. I hope this helps.

Cheers,

Morrie K.



__________________________________________________
Do You Yahoo!?
Yahoo! Greetings - Send FREE e-cards for every occasion!
http://greetings.yahoo.com

<<//\\>>//\\<<//\\>>//\\<<//\\>>//\\<<//\\>>//\\<<//\\>>

To view archives of postings, go to the Gambia-L Web interface
at: http://maelstrom.stjohns.edu/archives/gambia-l.html
To contact the List Management, please send an e-mail to:
[log in to unmask]

<<//\\>>//\\<<//\\>>//\\<<//\\>>//\\<<//\\>>//\\<<//\\>>