The FCC specificly allows multiple-subcarrier transmissions on HF but bans
"spead spectrum emissions using bandwidth-expansion modulation."
Multiple-subcarrier modes don't have to increase the bandwidth as the signal is
split into N parallel streams and each can occupy 1/N the bandwidth of the
original.
73,
John
KD6OZH
----- Original Message -----
From: AC TALBOT
To: digitalradio@yahoogroups.com
Sent: Friday, February 19, 2010 19:18 UTC
Subject: [digitalradio] (unknown)
The term "Spread Spectrum" can apply to any mode that spreads its
energy over more than the necessary bandwidth. If we assume the necessary
bandwidth to be equal to the signalling rate than anything other than single
carrier modes technically fall into this category.
Even WSPR coul dbe considered spread spectrum! Its 6Hz bandwidth is
wider than the 1.5 B/s rate. Within the WSJT suite, JT65 is more of a spread
spectrum mode, and outside Joe's suite, MT63 with its 2.5kHz for a few tens of
Bits / second is even more extreme.
Andy
www.g4jnt.com
