The efficiencies are really 'gained' when using SS in
a multiple access/crowded/relatively un-coordinated
system, ala a cellular system (CDMA), un-licensed and
usually un-coordinated use of a swath of spectrum etc.

GPS is a GOOD example of the use of SS - all birds
transmit in the same 'channel' with different, but
known, 'spreading codes'.

'Know the code' of the bird you are interested in
and the 'codes' from all other birds appear as
noise and are 'un-correlated' (not recovered).

Any differences between that pre-set 'spreading code'
of the desired bird is an information bit-stream that
contains 'data' associated with the desired bird.

Jim



----- Original Message -----
From: "Brandon Irwin" <BrandonI@LEAKED.INFO>
To: <PICLIST@MITVMA.MIT.EDU>
Sent: Friday, April 12, 2002 12:29 PM
Subject: [OT]:Spread Spectrum Efficiency for Continuous signals


>       I've been reading about spread spectrum and I don't see how spread
> spectrum techniques could be used for continuous transmissions.
>
>       Everyone seems to want to convert everything to spread spectrum
> because of its greater efficiency. I don't see how it could be any more
> efficient when used on continuous transmissions such as a TV video signal.
> The following assumes that they would keep the signal in the analog form.
> If you have four available channels with four TV stations and you
implement
> the freq hopping method, then all four channels will always be full
because
> the TV stations would never have a pause to allow a fifth channel to
> transmit. If you where to use a method similar to TDMA, then you would see
> little gaps in the picture.
> It seems to me that the only way the "more efficient" spread spectrum
> methods could be used would be to convert the signal to a digital form so
> it could be buffered on the TV side while the transmission ceased for
> whatever amount of time.
>
>       Is there something I'm missing? Maybe the whole concept?
>
>
>
>
> -Brandon Irwin
>
>
>
>
>
>
> -------------------------------------
> This message was written using the Dvorak keyboard layout.
>
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