Hello everyone,

First some background. I'm going to be building a simple stand alone data
logger for personal use (and the fun of creating it of course) since most stand
alone loggers are hundreds of dollars. I will most likely be using a pic18f4553
IIRC, and either interfacing to a ADC chip or using the on-board A/D. I also am
going to be interfacing to SD card since from what I've read they are easy to
do.

My question is, and I've searched high and low, how to implement compression on
this little bugger. Granted I suppose getting a jumbo SD card could negate any
compression done, but I may perhaps go to a simple serial EEPROM instead. All
the algorithms I've seen on-line seem VERY computationally expensive (which I'm
not sure if the PIC COULD do, or if it could would kill battery life never
sleeping) or memory hogs. I think I saw somewhere a person mentioned LZW
compression may work, with the difference from the current signal and last
signal. I have seen a few patents where they mention some adaptive data
compression using in audio but not much else. I understand that any voltage
signal is a wave form so an audio compression would probably be best? I would
like to go in a loss-less form. I would be measuring mostly things like temp,
humidity, sunlight, etc. A weather station would be it's primary focus, but I'd
like the option of using it for other things (or building a separate one more
tailored.). Does anyone know of a compression scheme that would work for such
things that it is worth the trouble to implement and extract some saving in
space? Maybe I don't need to worry at all? Also I am going to give
Sourceboost's C a try so C code references are OK. Sorry for the lengthy post.

Rob
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