Links

Heart Rate Sensor

Measurement of Heartbeat by Stethoscope Microphone

http://www.ymec.com/hp/signal2/heart5.htm

Habits of the Heart

http://www.smm.org/heart/tools/heartsensor/top.html

Build your own optical heart-rate sensor

http://www.elecdesign.com/Articles/Index.cfm?AD=1&ArticleID=6343

GPS Information

NMEA 0183

http://www.kh-gps.de/nmea-faq.htm

The NMEA 0183 Protocol

http://nmeatool.nmea2000.de/download/0183.pdf

Others

Atmel AVR Microcontrollers

http://www.atmel.com/avr