Doing some testing on a TomTom datalogger application I’m writing I’m finding some data gaps in the NMEA GPS output both from /var/run/gpsfeed and /var/run/gpspipe. At first I suspected the feed may not be sending out NMEA data during a loss of coverage, however recently observed the TomTom tracking OK during a period the problem was occuring. It is possibly because I’m attempting to log all data so that I can post-process the data for reporting and KML generation. To assist hearing when the data feed stops without taking my eyes of the road I’ve attached a piezo buzzer and diode to a DB-9 connector that seems to give an audible but not too annoying sound at 115200 bps.