The Timation system was designed to address some of the ‘holes’ in Transit that were caused by Transit’s special purpose specifications. Here’s some good background:
http://www.astronautix.com/craft/timation.htm
The difference in usability and performance caused by the time base infrastructure came home to me very clearly when I worked in Cheyenne Mountain during the 1980’s. We maintained a ’super-secret’ doomsday radio system that required very precise timing to stay in sync with other radios in the network. If a failure caused the system to lose it’s timing, a technician had to fly to Colorado Springs with a big atomic clock in the airline seat beside him and we’d have to carry the clock to the radio, deep inside the mountain, and “inject” time.
It was not only a hassle, it was an expense that out unit had to bear .. and the technician and his companion “Mr. Clock” were authorized first class airline accommodations because of the clock’s size. Even general officers are not allowed to book first class commercial flights, so you can imagine how PO’d the colonel got at the hits on his travel budget.
One day we had a ‘lost time’ event and I called the office to arrange for a visit from “Mr. Clock”. No need, they said, call these fellows up at the Air Force Academy, they have a GPS receiver. “What the heck do I need a nav system for?” was my response, “the radio is bolted inside 16090 feet of granite, we didn’t lose the radio, only it’s timing.”
Well, I did call the GPS guys and was amazed at how a (at that time) a briefcase sized box replaced the atomic clock by receiving the time signals from the few satellites then flying. The radio was back on line in a day instead of a week and the commandeer never bitched about the cost … great stuff, GPS, even in the dark old days.