Hi How much "warmup" time do you have before you go mobile?
If the mobile unit can be kept hot before it heads out - the DOCXO wins. If it's a "power up and roll in 10 minutes" sort of thing, then the Rb is the only way to go. Bob On Nov 19, 2010, at 3:56 PM, Dave Jabson wrote: > Greetings, > > I just discovered this mailing list, this is my first submission. Glad to > find a group of folks who are into this kind of stuff! > > I'm working on an data acquisition application for my company that will > require a very stable oscillator. Without going into too many specifics, > there will be some reference stations spaced 100's of kilometers apart from > each other and 1 mobile station that will be operated in an area where GPS > is not available. I need to be able to collect data at all the stations and > have the time synchronization be extremely good between the stations, > including the one without GPS. > > For the reference stations it will be sufficient to have the timing of each > one driven by a good GPSDO. Clocks will be sync'ed to UTC via the NMEA > string and 1pps edge and all of the digital electronics will use the GPSDO > 10MHz as their timebase. Periodic re-synchronization to the 1pps edge can be > done as needed. > > The mobile station can be synchronized to GPS initially to synchronize its > clock as described above but will then have to rely on a free-running > oscillator. The stability of this oscillator will dictate how much drift the > mobile station's clock will experience relative to the reference stations. > Keeping this drift as low as possible is my goal. > > I had assumed that a Rubidium oscillator would give me the best stability > over the course of 8-12 hours. Obviously a Cesium would be better but those > are impractical due to cost and power constraints. I've begun evaluation of > a Rb oscillator but now I'm being told by some people that a good DOCXO is > likely to give me similar medium term stability (with obviously better > short-term stability). > > Anyone here have thoughts on this? Obviously I'd rather go with a DOCXO for > cost and power reasons if there's no performance benefit to be had using a > Rb osc. The Rb unit I'm testing (http://www.thinksrs.com/products/PRS10.htm) > seems to perform well but I am interested in hearing others' thoughts. > > Thanks, > > Dave > > ---------------------- > > Dave Jabson > Systems Engineering Manager > Quasar Federal Systems > 5754 Pacific Center Blvd, Suite 203 > San Diego, CA 92121 > 858-412-1706 > www.quasarfs.com > > > _______________________________________________ > 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. _______________________________________________ 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.
