On Wed, 21 Jan 2004 17:40:24 -0800, "Lloyd Sumpter"
wrote:

I'm using Linux, so I'll attach the pulse signal to the interrupt and use Unix
signals to minimize CPU time. (Airmar says they output pulses about 4.8/sec at 1
knot, so max is around 100pps, or 10ms between rising edges).

Yeah, I expect that would be iffy on Windows. Sigh I was a unix
internals guy for Amdahl back in the 80's. SVID4 timeframe. I got
out of it just in time to avoid making money when *nix got popular. I
need to get a Linux box just for old times sake.

I think I'll be interfacing the GPS as well, so I can compare readings. I may
get energetic and write a "calibration program" that would average the two
readings and adjust the "fudge factor" for the knotmeter (assuming you push the
"calibrate" button, then run a specified distance, then back)

I've considered that as well. Right now, I just use my speed and SOG
graphs to eyeball the number. Since my KM and DS lose their fudge (I
can't believe I just typed that) factor when power is removed for too
long, I wind up doing it every season or so. Have fun!

__________________________________________________ __________
Glen "Wiley" Wilson usenet1 SPAMNIX at worldwidewiley dot com
To reply, lose the capitals and do the obvious.

Take a look at cpRepeater, my NMEA data integrator, repeater, and
logger at http://www.worldwidewiley.com/