[time-nuts] Thunderbolt controllers

Mark Sims holrum at hotmail.com
Mon Jul 7 17:14:15 EDT 2008

As I said:

>The Thunderbolt default config is to not save the survey position.  Unless you use some software to save the position...

The reason your Thunderbolt does no self surveying at power-on is exactly becuase you DID use some software to save the position!    The TAPR units were shipped with their brains washed clean of all previous existence.  In that state, a stock Thunderbolt will always do a self-survey at each power up and will not save the results.  You have to use some sort of software program to cause it to save the survey position.  People who just hook up the power and expect it to instantly start cranking out accurate frequency and timing are in for a surprise.  My first unit took three days to survey 1400 points.  I know of some that took over a week (due to long idled oscillators and/or very bad antenna coverage).

Also be aware that with a saved position  Thunderbolts gets all upset if you move more than 300 meters.  I'm not sure that it would recover without some human intervention... the manual is not clear on the subject and I have not tried to find out.  It is a "minor alarm" so I assume it does not totally die.

I would never use a PC to control the thing.  An obsolete PC compatible laptop makes the optimum controller in terms of user interface and cost.  The one that I am using draws less than 20 watts (15V, 1.2A).  Even less in power save mode.  I paid less than $50 for it.  Has a 1024x768 display,  40 gig hard drive,  256 meg ram, etc.  The program that I wrote needs none of that.  Would work fine booting off a floppy into 512K of RAM (DOS does have its charms).  With the 40 gig of hard drive,  you can log at one second intervals for 16 years.  

BTW,  on 30 July 2017 your Thunderbolt turns into a pumpkin...  its interpretation of the GPS week number fails and it may or may not keep working.  At a bare minimum,  the time and date will be wrong (see ThunderBoltBook2003.pdf page A-56.

I still want to do the MegaDonkey based microcontroller for the Thunderbolt.  Makes for a smaller, self contained unit.  One just can't do as slick and versatile of a controller with it.  It does have the advantage of drawing less than one watt of power.  There is a way to hook an SDRAM card / FAT filesystem to it for doing logging,  but I think I  will just pass log data out the second serial port and let people who are interested in that sort of stuff attach their own recording device.

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