A packet is a surprisingly delicate thing. It takes nowhere near
hypothetical 100 percent saturation with an RF signal to change one bit,
which can disrupt a packet.


Digital is magnitudes more robust than analog, again owing to the very
nature of the beast and the simplicity of the on/off, pulse width,
timing nature of the signal.


John I might respectfully suggest that you do a little studying on
the nature of digital signals. I've been dealing with them since the
late 70's, and they aren't anywhere near as robust as you believe.

Depends a lot on the encoding technique used. Amateur HF packet using
surplus Bell 202 modems is pretty bad in terms of interference handling.
COFDM with a rate 1/4 FEC is pretty good.

One needs to select a coding suited to the channel (e.g. using the
coding used for getting 56 kbps through a 3kHz phone line is probably
not appropriate for a ionospheric HF path).

I would venture to say that with today's technology, one should be able
to get within 0.5dB of the Shannon limit without too much trouble. So,
since a BPLish signal can be many MHz wide, and the putative interfering
signal is going to be pretty narrow band in comparison, they can code
around it.


- 73 de Mike KB3EIA -