[Laser] serial port PDM and PWM

[Chuck Hast]

On 12/7/06, Glenn Thomas <glennt at charter.net> wrote:
> uhhh... does anyone on here know how USB really works? I don't.
>
> BUT...
>
> The ten foot cable limitation is likely not a signal level issue. On
> a high speed, multiple node serial system like USB, it may be that
> there is a timing constraint that is inherent in the protocol. This
> type of limitation is found in etherNet (~100m) and 802.11 and is due
> to a sending station waiting only a small amount of time to receive
> an ack/nak before it concludes that the message wasn't received...
>
> BTW, if what you want to do is constant transmissions via a KISS-mode
> TNC, take a look at JNOS. Frankly, I'm too lazy to look up if JNOS as
> is will do constant transmissions. However, the source code for JNOS
> is freely available to Hams for non-commercial use, so you are
> welcome to modify it so it will do whatever it is you want.
>
> It seems like this thread is about replacing complicated soundcard PC
> software with equally complicated serial port PC software. Why not
> build a PWM modulator out of something like a pair of 555 timers?
> This way you have a (after integration at the receiver) a linear
> analog channel with significant bandwidth. If you build the same
> system with hardware that is faster than a 555, you can have a linear
> analog channel with a bandwidth that is tens of megahertz if not hundreds.
>

Well, I used to use JNOS and TNOS, back in the BBS days, but got out of
it, I do play around with the network parts though and work with others who
are trying to bring the packet network into some semblance of moderness.

With both the IP stack and the AX25 stack in Linux why add a second one?
I have two switches, one my test switch and the other soon to be the Tampa
switch (we are replacing a old DOS based switch) and I can do all I need
with the Linux IP and AX25 stacks, and have also at my disposal the fpac
and netrom stuff, on top of that I have a link to a BBS that can spew forth
enough to keep several links busy.

All of the amateur stuff in Linux is Open Source so any of it can be quickly
looked at for whatever is needed. Besides, I too am too lazy to get in and look
at another, it was enough trying to learn what I have.  B-b


What we want to send is digital data, OOK is the simplest way to do it so
might was well start there. Any port that can supply the proper signalling is
a start, serial, parallel, I guess you could bit bang the parallel port too and
get data in and out of that.

-- 
Chuck Hast  -- KP4DJT --
To paraphrase my flight instructor;
"the only dumb question is the one you DID NOT ask resulting in my going
out and having to identify your bits and pieces in the midst of torn
and twisted metal."