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Jim Granville
02/28/13 13:09
Read: 831 times

#189518 - They have a serious system
Responding to: Daniel Jenkins's previous message
Daniel Jenkins said:


The equipment consists of 4 Arbiter GPS Receiver/Clocks tied to 4 computers to supply extremely accurate Time-of-Day from the U.S. GPS Satellite Network. A 5th computer is used to provide totally independent, manually generated, average speeds as a back up to the double redundant electronic system. A GPS synchronized atomic clock with large LED numbers will be on display at the starting line to signal the start of the event for each participant. Infra-red beams will record car passage at the Finish Line on two additional independently operating computers. The GPS Time-of-Day is automatically updated from the GPS Receiver/Clocks each time a car starts or passes through the infra- red beam.


As each car is in position, ready to start, the atomic clock will display the accurate GPS time. You will be signaled to start your time at the top or bottom of the next minute. When the clock reaches this time, this is your start time to be recorded by the computer. YOUR ELAPSED TIME HAS BEGUN! At the Finish Line, the GPS Time-of-Day will be recorded by the breaking of the infra-red beam. The precise location of the infra-red emitters will be clearly marked with large red traffic cones at the Finish Line Banner, Mile Marker 7, in Lincoln County. The start and finish times will be automatically computed to provide the elapsed time, average speed, and variance for each participant.


Does this mean I should be able to tap into their time via GPS signal?

Yes, that is good news, you should be able to have your own GPS-lock, (with a TXCO covering drop-outs) - GPS boards with 1pulse per second are sub $50, and TCXO are sub $5, so it is affordable.
You could spend more $ and effort if you wanted full time strings, but you should be able to manually lock to the 1pps.

- and it still looks like a Manual Sync, even tho the real sync is hidden ;)

Small phase difference here should not matter, as the relative time should not move during your trip, so you will have time precise to under 1ms
(and you can check your TCXO drift, whenever you have GPS signal, if you want to push under 1ms, or just reality-check you are sub-ms.

Daniel Jenkins said:

The distance error can be addressed with a manual reset a few miles out on the last straight. I can use any existing landmarks, but I believe adding your own is frowned upon.

hehe, yes, I can understand it is best to avoid 'adding your own', besides the clutter, the temptation to move someone else's mark would just be too great ;)

Are you allowed cameras, for the way-point read ?

List of 19 messages in thread
Looking for direction - racing application      Daniel Jenkins      02/22/13 23:46      
   step by step      Erik Malund      02/23/13 06:29      
      First step...      Daniel Jenkins      02/23/13 11:20      
         well, you are new      Erik Malund      02/23/13 13:08      
         First, check number sizes and precisions       Jim Granville      02/23/13 15:51      
            Good catch on the clock accuracy.      Daniel Jenkins      02/24/13 01:10      
               Judging      J. Guy      02/25/13 11:17      
                  Judging      Daniel Jenkins      02/26/13 12:25      
                     Rethink your solution      J. Guy      02/27/13 11:04      
                        Not sure we're seeing eye to eye...      Daniel Jenkins      02/27/13 20:16      
                     think precision       Jim Granville      02/27/13 13:44      
                        Increasing accuarcy      Daniel Jenkins      02/27/13 20:28      
                           Precision still matters.      Jim Granville      02/28/13 02:17      
            Precision distance!      Oliver Sedlacek      02/28/13 05:09      
               Rulebook on timing      Daniel Jenkins      02/28/13 11:37      
                  They have a serious system      Jim Granville      02/28/13 13:09      
   very imprecise      Erik Malund      02/28/13 13:37      
      re:      Jacob Boyce      02/28/13 14:52      
         re: speed      Daniel Jenkins      02/28/13 16:45      

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