Trimble ThunderBolt GPS frequency standard, no "Stored Position" lock? - Page 1
Forum section: electronics / general

author: Chris Wilson
author_rank: Super Contributor
timestamp: June 12, 2012, 06:52:19 am
content: I left my newly acquired Trimble Thunderbolt running from a reset fromThunderbolt Monitor all last night but this morning it still hasn'tachieved a "Stored Position" lock. Is it normal to take a long time todo this, or is a setting wrong somewhere? I have put a screenshot ofthe monitor as I found it this morning at:http://www.chriswilson.tv/trimble.pngIt has also always shown a "Leap Second Pending minor alarm, but Ibelieve this is quite usual?Thanks.

author: gxti
author_rank: Frequent Contributor
timestamp: June 13, 2012, 03:20:57 pm
content: Greetings, fellow time-nut!You can see on the left that the "self-survey progress" is at 0% which means it hasn't auto-triggered for some reason. You can manually initiate a self-survey using either Trimble GPS Studio or Lady Heather. It's probably possible with the tool you're using but I'm not familiar with it, poke around in the menus at the top and it should be obvious.

author: Chris Wilson
author_rank: Super Contributor
timestamp: June 13, 2012, 04:06:49 pm
content: I have managed to force it to do a self survey, but after nearly two days it still hasn't set itself a stored position. maybe I need to now enter the accurate position manually and store it like that? I was expecting it to do this automagically. Thanks for the reply gxti

author: aghp
author_rank: Regular Contributor
timestamp: June 13, 2012, 07:29:11 pm
content: Tboltmon and do factory reset. (But I believe you have done it)Shut off and then on.It survey automatically and then it stop survey after it is 100% and it continue then locked "fine" discipline.It is made just so simple that no need do anything! "Blonde installable"(becouse it is made for commercial use no one have money to travel every location and "command and adjust it" it is really too expensive. Also if TB fails and it need change. Just failed out, new in and go. So it is factory made just for plug in and go. )But IF someone have made some settings and stored them to eeprom... for this. Always start TB doing first factory cold reset if TB is not factory new from box and you do not know exactly its status.I have started (and tested maybe 50 thunderbolt and never find problem in survey if antenna is ok.)With factory defaults it survey once (it can also program how long it survey before position is iterated enough accurate)(and also it can store location after survey so that next start after power off is fast.)hand made location is not so accurate and it may lead high inaccuracies in timing and freq stability. It need be this precision position what is "precise with thunderbolt own eyes."But then if want make it more accurate for frequency standard use it need some adjustments optimised for freq stability over time accuracy. Factory defaults are not best for this. Also these units are well aged so after owen is stabilized well there can do some tests for finding and change some parameters for better discipline. It depends individual unit.Also depend of location and satellite visibility there may need some special settings for satellite paramaters.Some small things may be related what version TB you have ... maybe rev 3.0 ?

author: Chris Wilson
author_rank: Super Contributor
timestamp: June 13, 2012, 08:44:39 pm
content: Excellent info. thanks aghp. yes, it's a rev 3.0 and I want to use it as a frequency standard. I have got it to lock position manually by entering the latitude and longitude that the ThunderBolt had decided on after a few hours running. I then ran lady Heather for an while and there's a screenshot attached, not sure if it's run long enough to give meaningful results yet? Thanks again for your help, you sound like you know these things well

author: Rufus
author_rank: Super Contributor
timestamp: June 14, 2012, 12:24:11 am
content: Quote from: Chris Wilson on June 13, 2012, 08:44:39 pmWhich tells me which corner of the house you mounted the antenna - ain't technology wonderful.

author: aghp
author_rank: Regular Contributor
timestamp: June 14, 2012, 09:59:27 am
content: Update previous:Using Tboltmon.exe assuming that it communicate ok with TboltUsed Tbolt, unknown status and settings stored in eeprom:Simple setup:First: Tboltmon.exe open Control menudown there is Factory reset. Do it. (accept it with OK)After Tbolt is up agengo to Setup menuopen Self-Survey...in this window set "Save Position Flag" to "Save" (if it is not).and if installation is finished and run example survey lenght 10000 and all is ok, then also set "Self-survey to Disable")IF you are just exercising do not change yet anything and go now out from this menu,IF you want do this/these setting then continue:change settings as need/wantthen push "Set survey"Next push: "Save Segment"Look your antenna see satellites.Go to out and let Tbolt survey and fix.After 1 - x hours it is fixed and discipline normally.----------These factory defaults are not very good for individual units and best frequancy stability.Survey lenght may be example 10000 (setup menu, self survey)satellite elevation need think what is best. (and other parameters in setup menu GPS receiver)Oscillator discipline paramaters (setup menu, discipline)- loop dynamics (it affect lot of for "short" term freq stability. (default is more for time accuracy weighted)- Oscillator tuning parameters. (these need manually test and set for individual unit/Owen) Default value is very rough.- Initial Dac Voltage. (if better selected for individual unit(owen) it recover from power off more fast for more close right 10MHz) (after month continuous use you see what is last week average and example this can set as initial)It need note that Tbolt is "very" sensitive for enviroment temperature. Of course it is not problem in original use becouse unit can drift freq "lot of" and always quite fast adjust and keep timing inside limits.In frequency standard use it is different. It need littlebit different parameters for best result.(long time average is different... some hours average is always good (with defaults) if satellite visibility is any kind of acceptable.)

author: donmr
author_rank: Regular Contributor
timestamp: January 03, 2015, 06:00:45 am
content: Can you (or anyone else) suggest better Loop Dynamics settings for use as a frequency standard?Is there good reference info on this somewhere?Thanks

author: TSL
author_rank: Regular Contributor
timestamp: January 03, 2015, 06:47:14 am
content: you can try these links for starters...http://www.ke5fx.com/heather/readme.htmhttp://www.ke5fx.com/tbolt.htmhttp://www.ko4bb.com/dokuwiki/doku.php?id=precision_timing:lpro_disciplining_with_thunderboltLots more here...http://www.ko4bb.com/dokuwiki/doku.phpregardsTim