Data Hacking

126 Part II — Software Hacks
Managing data
Data display
Interpreting data
FIGURE 6-1: The basic functions of a GPS receiver
As you can see, being able to influence the firmware means you have influence on the actual
workings of the GPS receiver itself. Not only can you make alterations to the text that is displayed
on the screen of the GPS, you can also hide features that get in the way (such as startup
screens). You can also add your contact details to the GPS in such a way that would discourage
theft of your unit and encourage its return to you if it were found.
But you have to be careful . . .
Updating Warnings
Reception of data
Data processing
Decoding
Data conversion
External
communication
You must be careful when making any changes or modifications to the firmware of your GPS
because there is a risk that things can go wrong and render the GPS inoperable. Problems are
rare, however, and you can take steps to reduce, if not eliminate, firmware update problems:
1. Make sure your GPS contains a new set of batteries. Batteries suddenly dying midfirmware
updating could cause big problems. Add fresh or recently recharged batteries,
fire up the GPS, and confirm that the power levels are high. Figure 6-2 shows a healthy
battery level in the lower-left corner of the screen on a Garmin eTrex.
2. Because you will be using a PC to do the update, it is better if the PC is connected to a
UPS (uninterruptible power supply) battery backup, because the PC shutting off midupdate
can be just as bad as the GPS battery dying. If you are using a laptop, power it
from the mains supply or make sure the battery is fully charged.