clumsy ******* wrote:
"Dave Plowman (News)" wrote:

Just when I thought I had the basics of the subject licked, you say
that. Could someone briefly explain the difference?
I just hope there is one. My phone appears to think there is.

ah, OK.
there are many modulation schemes and at least two different
frequencies..in use. and several different encryption schemes.

Its a wonder any of it works at all!