In addition to the handheld DAGR there is a 12 Channel printed circuit board version called the Ground Based - GPS Receiver Application Module (GB-GRAM).Note a Ground Based application will have velocity, acceleration and jerk values much less than those encountered in air and space craft and a GPS can exclude the higher values making for a better solution.More importantly GPS receivers rated for air or space usage have more ITAR controls on their distribution.
The diagram below shows the evolution of the Rockwell GPS receivers.
It's a 5 channel L1 receiver that can be used with both the CA and P (when keyed) codes.
as of July 2010 I suspect that a Software Defined Radio type architecture is used.
This means that the DAGR/Polaris can receive the in development L1C, L2C, L5 and M codes with just a firmware upgrade.
Also there are a number of GNSS (Wiki) signals that probably can also be received.
When the receiver is reprogrammed it probably will still have the same number of channels but how they are allocated in frequency and code is TBD. The military WAGE (Wiki) is either global or area specific.
There are similar augmentation systems for other parts of the world.
The L5 signal allows for ionospheric corrections making aircraft (and all other) systems much more accurate.
Another aspect of Safety of Life is signal integrity allowing the user to know he has a good solution and when he doesn't.
WAGE is only available after the GPS crypto key is loaded.
harmonic of the 10.949297 MHz crystal used in the Rockwell Collins GPS receivers (see Polaris Link below) in order to center the LO between L1 and L2 so that a single LO can be used for both frequencies with the same IF frequency of 173.91 MHz.