[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.
>
> 73 de Glenn wb6w
>
>
> WAR IS PEACE!
> FREEDOM IS SLAVERY!
> IGNORANCE IS STRENGTH!
> (be seeing you!)
>
>
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-- 
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."