The Amateur Radio service used LSB under 10 Mhz (3.5 and 7.0 Mhz band allocations) and USB above 10 Mhz (14.0, 21.0 and 28.0 Mhz band allocations). CW is used in the lower section of each band allocation.
Above 30 Mhz FM is generally used.
HF range = 3 to 30 Mhz
VHF range = 30 to 300 Mhz
The Wireless Institute of Australia <a href="http://www.wia.org.au/" target="_blank">http://www.wia.org.au/</a> have some excellent training material available on RF propogation.
ARS: VK4VEE
[ 30 December 2001: Message edited by: Torres ]</p>