Hi Al,

I've been pursuing an RF link myself so any relevant info I find is
helpful. So, I decided to check out your design. I skipped ahead to see
what kind of encoding method you're using. I then came across this:

"A short pulse is a 0 and a long pulse is a 1.
This is Manchester encoding and has the benefit of being self-clocking
and relatively immune to time variations."

From what I know, this isn't Manchester; it's pulse-coded data. It's
what Sony uses for their IR protocol. Manchester on the other hand
represents 1s and 0s by change of signal level. Each bit uses the same
amount of time but it cuts your total bandwidth in half. To send a logic
one, you hold the line low for half a bit period then yank it high. For
a logic zero, you hold the line high for half a bit period and pull it
low. Of course, this isn't carved in stone, I've seen designs reverse
this.

If I'm totally wrong, please forgive me.

-Tim Hamel

Al Williams wrote:
>
> Our "Basic Stamp Project of the Month" this month is relevant. The
> system I show is slow and one way, but it is cheap (maybe not quite as
> cheap as the -um- machine) and readily available. A PIC could drive it
> much faster (much of the slow speed is to allow for the Stamp's
> processing latency) although it would never be high speed. In theory,
> you could adapt the
> system for two way, although I haven't personally done this.
>
> Anyway, might spur some ideas. The project of the month changes each
> month and is always at: http://www.al-williams.com/awce/som.htm
>
> We call it the Basic Stamp Project of the Month, but we occasionally do
> PIC, SX, or just general-interest projects.
>
> Good Luck!
>
> Al Williams
> AWC
> * Check out our PIC Programming Tutorial
> http://www.al-williams.com/pictutor
>

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