>-----Original Message----- >From: piclist-bounces@mit.edu On Behalf Of Olin Lathrop >Sent: Wednesday, January 11, 2006 7:26 AM > > >1 - Buy a frequency reference. These are commercially available to better >than 5ppm using calibrated crystals that have been aged and are actively >temperature controlled. HP used to make a portable cesium >standard for only a few 1000 $, but that sounds like rather overkill. The Dallas/Maxim DS32KHZ 32.768kHz TCXO has a worst case accuracy of 2ppm over 0 to 40 degC and 1ppm/year. They are in stock in DIP packaging for $10.00 at DigiKey. Jinx might even be able to get one as a free sample from Dallas/Maxim. Maybe pair one up with a PIC to use for calibrating the other units. Paul Hutch -- http://www.piclist.com PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist