Hi: The antenna is on a mast about 6 feet above a chimney top. There are a number of surrounding 100 foot trees and this caused a lot of jitter last year due to multipath. I fixed that by changing the elevation mast to 50 degrees and that's where it is now. Changing the elevation mask to 70 degrees still shows 400 ns of jitter for a 10 second average. I doubt that any trees are in that cone.
I'm in the zero-degree timing mode and have a surveyed antenna location and so don't see Lat-Lon-Alt type outputs. For some averages of 10 seconds the jitter is in the 9 ns range but for others are in the 300 ns area. Turning Tropo Corrections off seems to lower the jitter. Thanks, Brooke Clarke Rob Kimberley wrote: >Brooke, > >GPS is affected by heavy rain. Signal will be attenuated, and some at low >elevations may be blocked. Snow is even a worse culprit especially if it >settles on the antenna. > >Do you have antenna mounted in the clear or do you have any partial >obscuration from buildings or trees (especially wet ones!)? > >Best > >Rob Kimberley > >-----Original Message----- >From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On >Behalf Of Brooke Clarke >Sent: 05 March 2006 20:03 >To: Discussion of precise time and frequency measurement >Subject: [time-nuts] FTS4060 Continuing Saga > >Hi: > >After Tom helped me a month ago to get the trigger level correct for 50 Ohm >loaded TTL (1.25 volts), I've been seeing no aging on the FTS4060 s/n 1013 >and have been tweaking the C field and all was going well, but today (heavy >rain) the jitter on each 500 second average has jumped up from about 9 ns to >more like 300 ns which means you can not believe the readings. It's snowing >on the nearby mountains and heavy rain here. > >Note that on prior days the daily spread in the Time Interval has been >around 10 ns peak to peak. > >So does GPS suffer with heavy rain? > >I checked TAC32 and the receiver settings are correct. > >Interesting sidelight: >A couple of days ago there was a brown out the caused the SR620 counter and >the computer to reset, but the FTS4060/S24 (no backup battery) did not reset >(Lock and AC ON green LEDs) and the data shows that there was a recovery >that lasted about 1,500 seconds. Not sure what was moving. > >Have Fun, > >Brooke Clake > >-- >w/Java http://www.PRC68.com >w/o Java http://www.pacificsites.com/~brooke/PRC68COM.shtml >http://www.precisionclock.com > > >_______________________________________________ >time-nuts mailing list >time-nuts@febo.com >https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > > > >_______________________________________________ >time-nuts mailing list >time-nuts@febo.com >https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > > > > -- w/Java http://www.PRC68.com w/o Java http://www.pacificsites.com/~brooke/PRC68COM.shtml http://www.precisionclock.com _______________________________________________ time-nuts mailing list time-nuts@febo.com https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts