[time-nuts] Thunderbolt Monitor (Didier Juges)

[WB6BNQ]

   Hi Dave,

   Personally I question the value of such an item.  As hobbyist we all
   start immediately planning such a project just because that is our
   nature.  The Tbolt monitor program provided by Trimble, while lacking
   in some regards, is adequate for determining the functional condition.
   If it is working then most people are going to ignore it as its job is
   just to sit there and do its job.  Very mundane stuff in the aggregate.

   Probably the biggest thing missing in the Trimble software is a
   pictorial view of satellite placement.  Unless an expensive graphics
   LCD where planned, it would be out of the range of a simple PIC type
   project.  As most all who use a Tbolt would have a PC laying around, it
   reduces the need for such a project.

   That said, were such directions taken seriously, I think it should be a
   group effort.  This way those who seriously want to produce such a
   project can collectively arrive at a single meaningful product.  This
   project would be a good one to funnel through TAPR in a kit form.
   While not a member of TAPR, I can see their usefulness as a focal point
   for furthering interest in such projects and it provides a larger
   audience besides us Timenuts.

   It seems that projects like the TAC2 and such have died out at TAPR
   though the GPS/time arena still is a high interest.  Probably because
   the TAC2 idea was made into a commercial product.  Also because of
   Motorola dropping their efforts at making GPS receivers at a time when
   it was unclear if anything was going to be available to replace them.

   Perhaps, from a view of the bigger picture, we can generate a renewed
   interest to satisfy several needs at once.  Currently, only three
   useful items I can think of provide an interface between the GPS signal
   and one's local house standard.  The REFLOCK, Brooks Shera and a third
   party's lesser idea of something similar to the Shera controller.  Of
   the three, I think the REFLOCK was designed for a different purpose in
   mind.  Of the remaining two, The Shera controller is the more serious
   and complete design, particularly considering its design concepts went
   into a commercial product.

   The point of all this is a new person getting into the GPS locked house
   standard game is faced with several issues.  Sure they buy a Tbolt (or
   something similar), but then they have to figure out how to use it.
   While the Tbolt provides a direct 10MHz output, there are a host of
   reasons why you would want to buffer its existence.

   Having a house standard sure looks pretty sitting there until you
   realize the damn thing is not doing anything other then sucking power.
   Except for an extremely small number of people (count like 3 or 4 {no
   disrespect intended}) who have the means to stock a major museum or
   have a fetish for mechanical clocks, the normal person is going to want
   their house standard to do something useful for them.  So, we have the
   problem of either distribution or comparison.

   To distribute clean signals in different directions is not so easy,
   although, currently, a product is available at TAPR for this function.
   Distributing a signal has its limits and does not satisfy every
   situation.

   That leaves us with the need to compare lesser devices with the house
   standard.  This is where the system breaks down.  The one thing that is
   most plentiful is the oscilloscope, however, having your eyes glued to
   scope for any length of time is quite tedious.  Such items as the
   TRACOR 527 Frequency Difference Meter are available, but they are no
   different then using the oscilloscope in that the measurement is
   instantaneous, thus providing no history.  Besides things like the 527
   are expensive and not plentiful.  A phase discriminator along with a
   chart machine could be used for long term monitoring.  However, the
   need for lots of hard to find (sometimes) chart paper is a serious
   distraction.

   To wrap it up, here is what I see as a useful project:

     1.  It should contain at least two independent Shera type controller
     circuits for locking two separate independent house standards
     against the GPS signal.

     2.  Additionally, it should contain at least a single independent
     DVM display to select and watch the two [item 1] DAC values plus the
     ability to feed information of those separate actions to a PC.

     3.  It should contain a third Shera type circuit to use as a
     comparison channel between either of the two mentioned house
     standards so that other lesser, uncontrolled devices can be
     calibrated.

     4.  In Lieu of item 3 a similar arrangement to the TRACOR 527 as the
     third comparison channel.

     5.  In reference to items 3 and 4, the onboard controller should
     provide some readout for the calibration function.  Preferably,
     include an analog meter and the means for the onboard controller to
     provide some limited means of giving an averaging over time readout,
     plus the ability to provide this data to a PC.

     6.  As we have lots of TIME (pun intended) running around this
     board, consider the ability to provide time stamping.

     7.  Provide the ability to read several temperature devices.
     Something as simple as the DALLAS One-wire devices as probes would
     work.

     8.  This project could be implemented with several CPUs,
     particularly if using the Shera circuits, without too much trouble.

     9.  To make things easier as a kit, design it using thru-hole
     devices, particularly the CPUs. (Partly said in jest)

     10.  Do not forget to include an onboard negative supply system so a
     single positive supply is all that is needed.

     11.  Regarding the data to a PC, provide it as ASCII data that is
     comma delimited so graphing could be accomplished in an EXCEL type
     spreadsheet program.

     12.  Almost forgot.  The ability to communicate with the Tbolt and
     perhaps the M12M type receiver.

     13.  Finally, PLEASE design for lighted LCDs or, better yet, using
     bright Vacuum Fluorescent displays.

   I think such a project would be worthwhile.  It could be done as a kit
   in such a way as to be implemented in stages if one does not need or
   want the full capability.  For that matter it could be done as a
   motherboard with daughter cards to implement, for example, the three
   Shera circuits.

   This is my synopsis, right, wrong or in between.  I hope I have not
   offended anyone with such a lengthy diatribe.

   Bill....WB6BNQ