John Smith I wrote in
:

Dave Oldridge wrote:
John Smith I wrote in news:fa4i2a$jve$1
@news.albasani.net:

Dave Oldridge wrote:

...
You need a good book on digital error correction algorithms in
digital communications.

Unless you have constructed a real rf jammer (white noise really),
BPL will eat up any legitimate amateur communications you can throw
at it ... however, rumors do prevail, like the one about the tin
foil hat.

So how is it gonna eat up having its receiver saturated? I'm pretty
familiar with digital comms and, with the exception of some pretty
slow speed stuff designed for weak signal work, most of it is not
very good unless you have a really solid signal-to-noise ratio. I'm
just saying that if it's getting out to my antenna that loud, then my
kilowatt is gonna have a fair chance at saturating the thing's
receiver. And the more noise they make, the more I'm apt to have to
use the kilowatt to shout over them.

Of course in our current enforcement situation here, I'd probably
simply be told to stand down and have to go to great legal lengths to
appeal the ruling.


Digital is not analog, when adverse conditions have made an analog
signal totally unusable, a digital signal, most likely, may still be
achieving 100% error free data transfer--it is just the nature of the
beast.

Actually, I've found that, except for very slow data rate stuff, digital
signals require a BETTER signal-to-noise than analog to be readable. And
there is no partial readability with most of the commercially-used
digital modes. That is to say you either have error-free transmission or
none whatever.

The "intelligence" of the software controlling the data
transmission(s) is the single most important factor--as logic would
dictate. Even under almost total saturation (it would be virtually
impossible for 100% saturation, baring hooking the kw+ rig directly to
the power lines) of the BPL signal some type of heterodyne would be
occurring with the KW signal. Since digital is simply detecting an
ON/OFF signal, in conjunction with spacing/length of these, an on/off
signal is still detectable in this heterodyne--given the software is
aware and capable of reading this signal and switching "modes" to do
so, no harm is done to the data ... and without doubt, new error
correction methods will also develop as BPL grows and
hf-rf-terrorist-hams challenge this system ... LOL!

You cannot recover data with a modem whose input transistor is biased off
by rectified RF. I know this. I've tried it.

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.

The only real advantage digital has is its error-correction algorithms.
Those can do very good work when they actually have enough data to work
with. But once the data recovery by the the very ANALOG device that is
receiving the signals drops below their threshold, then the recovery
becomes terrible. Some modems are better than others. My old Telebit
19.2K could suck 1200 baud recovery out of a phone line you couldn't talk
on. But give it a couple of volts of RF in the mix and it would drop
stone cold dead. And BPL has the "disadvantage" of not being able to
filter our frequencies AND use them at the same time. At worst, I'd
drive the BPL machinery to other parts of the band from where I was
working....


--
Dave Oldridge+
ICQ 1800667