[time-nuts] Thunderbolt controllers

Rob Kimberley rk at timing-consultants.com
Mon Jul 7 17:53:13 EDT 2008

If you look at what a Thunderbolt was originally designed for (a fixed cell
site T&F reference), then you are right, they are designed to be powered up
and left to sort themselves out - self survey, and then provide T&F outputs
when everything has stabilised.

Rob K

-----Original Message-----
From: time-nuts-bounces at febo.com [mailto:time-nuts-bounces at febo.com] On
Behalf Of Mark Sims
Sent: 07 July 2008 22:14
To: time-nuts at febo.com
Subject: [time-nuts] Thunderbolt controllers

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

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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