DSSS is nowhere near the best modulation format in the presence of
narrowband
interference. OFDM is far better suited in this case as was shown in ADSL
trials (examing the effects of cable crosstalk). We found the same during
our
amateur spread specturm experiments in Dallas in the 902-928 MHZ band in
the late 1990s where DSSS was far inferior to frequency hopping with bad
channel notching.

-- Tom, N5EG




"Paul Rubin" wrote in message
...

SNIP


I wonder why anyone is messing with these modes instead of doing DSSS,
now that we can digitally-process the daylights out of the received
signal instead of messing with analog filter banks or whatever. I've
been hoping for something even slower than PSK31, spread over an
entire ham band or even multiple bands. I'd think something like that
would be ultra-reliable through just about any amount of interference.

"TOM" writes:
DSSS is nowhere near the best modulation format in the presence of
narrowband interference. OFDM is far better suited in this case as
was shown in ADSL trials (examing the effects of cable
crosstalk). We found the same during our amateur spread specturm
experiments in Dallas in the 902-928 MHZ band in the late 1990s
where DSSS was far inferior to frequency hopping with bad channel
notching.

I was thinking in terms of DSSS on the HF bands, for reliable, long
haul data traffic at very low bit rates. Am I nuts?

Well, if anyplace has severe narrowband interference, I would think that
HF would surely be it.

-- Tom, N5EG


"Paul Rubin" wrote in message
...
"TOM" writes:
DSSS is nowhere near the best modulation format in the presence of
narrowband interference. OFDM is far better suited in this case as
was shown in ADSL trials (examing the effects of cable
crosstalk). We found the same during our amateur spread specturm
experiments in Dallas in the 902-928 MHZ band in the late 1990s
where DSSS was far inferior to frequency hopping with bad channel
notching.

I was thinking in terms of DSSS on the HF bands, for reliable, long
haul data traffic at very low bit rates. Am I nuts?

"Paul Rubin" wrote in message
...

I was thinking in terms of DSSS on the HF bands, for reliable, long
haul data traffic at very low bit rates. Am I nuts?

Here's a way to get reliable, long haul data traffic at low bit rates:

http://www.uspacket.org/plan_a.htm

Charles, N5PVL