On Wed, Feb 15, 2012 at 9:12 AM, Bob Camp <[email protected]> wrote: > Hi > > Which still gets us back to - why the really odd sweep on the FE's? and > should you center the VCXO as a matter of routine maintenance?
I think a very asymmetric sweep makes the most sense. First some history of sailing ships. Back in the 1600's navigation was not perfect and you never knew your exact position on the open ocean. Knowing within 30 miles was hard to do. So to get to a given location in North America from Europe they typically would aim about 50 or more miles to the north of their intended destination and then when they reached land would sail south until they found the destination. This added a day or more to the trip. If they tried to hit the target dead-on they would likely miss but then they'd have to literally guess wetter to go North or South and if they guessed wrong it could really be bad so they always headed for enough north of the target so there was no guessing about which way to turn. I think the sweep is done the same way. If you start way low you know 100% which way to go, the lock has to be up. Seeing as we know they are using software in the loop this makes sense. So on pwr up the uP starts looking with bottom up sweeps. The sweeps fail to find lock because the temperatures of the crystal and Rb are to low but after some minutes, finally a sweep finds the lock Chris Albertson Redondo Beach, California _______________________________________________ time-nuts mailing list -- [email protected] To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
