Russell McMahon writes: >Completely different suggestion - would GPS meet your need? >Limited indoor use due to shielding by buildings may be a killer. >Modules getting very cheap. >Extremely easy to interface to. That is a great suggestion. If it wasn't for the indoor signal reception problem, I wouldn't even consider the LF radio solution. Maybe I should buy a module and see if enough signal leaks in to our house through the windows or walls to be reliable. Martin McCormick WB5AGZ Stillwater, OK OSU Information Technology Division Network Operations Group -- http://www.piclist.com PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist