Even the earliest Apollo-NG design drafts already included multiple GPS dependencies for a number of subsystems. Apart from obvious navigation assistance, GPS will also discipline the reference clock module and the 10MHz reference oscillator module GPSDO. The first prototype was hacked around an old Rockwell/Connexant Jupiter TU30-420-031 GPS receiver, found on eBay.
Unfortunately, this module is relatively old, consumes too much power and it's hard to get a replacement module in case of failure. It only supports 10 channels, speaks a very narrow Zodiac Binary protocol, NMEA is almost unusable and it only offers 10kHz sync output, making a frequency divider neccessary in order to drive the PLL of the GPSDO. After a lot of work on #gpsd and some kernel hacking to get Kernel-PPS support on ARM, the reference clock worked reasonably well (UTC Offset: 17 nanoseconds avg):
After evaluating many GPS chips, uBlox's LEA-6 series seemed to be top notch, in every aspect:
Gitte Jensen, Corporate Communications Manager for uBlox, understood the Apollo-NG concept directly and went all the way, not only sponsoring just a GPS chip, but 4 GPS Modules (2x LEA-6T + 2x LEA-6R) AND the matching Development Kits as well. The Odyssey can now fly with a high-end GPS setup, employing active fail-over redundancy. If one GPS module should fail, the other can take over the sibling's dependencies with a slight decrease in specific use-case precision. So, all you boys, girls & gender-neutral beings, interested in GPS technology and uBlox implementations, now you can just take the DevKit and directly start to plug & play. uBlox should be grateful, to have such a far-sighted Corporate Communications Manager who does a great job, representing a company, that tries to fulfill its social responsibility by taking care of future engineers and young enthusiasts.
The reason why I am interested is, that we, within our CSR program, strive to enlighten young people to the exciting world of engineering. Gitte Jensen, uBlox Corporate Communications Manager
Thanks a lot to uBlox and big hugs to Gitte, for her great support.