I have noted that this GPS unit has a prob when been powered off for ~72+ hours. The problem is that it resets itself back to binary mode, the quick way to tell this is there is no LED activity on the side of the unit. This unit optimally needs to be run in NMEA mode. To get this unit in to running in NMEA mode is very easy, while the unit is plugged into your computer you just have to issue it a command.
The command string to issue to it is:
$ gpsctl -n -s 4800 -t SiRF binary /dev/ttyUSB0
After running the above command you’ll notice that the LED on the side has come alive and will be steadily flashing. Now you’ll beable to use your GPS unit to its full potential.
For further info and help:
$ man gpsctl