>I haven't seen anybody mention the advantage of eliminating multi path
>fading problems with SS.

I didn't want to get that deep into it :)

>In an industrial environment with transmitters moving around you could have
>several paths from the transmitter to the receiver due to the signal
>bouncing on the surrounding structures inside a building. When two
>different paths differs in length with a multiple of one half wavelength,
>the signal could effectively be blanked out at the receiver. By
>continuously changing the channel this problem could be limited to just
>some channels.

This is called "diversity reception" and might be applicable while
hopping, but SS is different enough that you can't just ignore
some channels.

>This requires that the system allows that data that is lost at some hops
>could be retransmitted in another hop, just like collisions in a CSMA
>scheme, which implies that it isn't suited for continuous transmission.

As I said before, in SS each bit is spread over several hops.  And it's
worse (or better) than that.  The hopping is so fast that the each
"hop", as we would think of it, doesn't look like a discrete signal
on a certain frequency.  It is a wideband signal that covers a large
range.

>I don't really know if this works in practice but it is one of the
>advantages that is mentioned in favor of using SS methods.

What they actually are able to do is see the echoed signal being
received at a later time (remember SS clocks are _fast_) and
so they can recognize and filter them out.

When I heard this last item, I said, "If they can see them they ought
to be able delay them and add them back into the real signal to
recover even more of the signal."   I don't know if that's been
done but it seems obvious so I expect they have.

>>
>> -Brandon Irwin
>>
>> -------------------------------------
>> This message was written using the Dvorak keyboard layout.

lgid ks mddk tsfw mo h.sipv
or is it
bcj. yr m..y frgw mp ekrpat

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