[ANSWERED] PDR Fix and Improvements
05-16-2016, 08:40 PM
#21
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Originally Posted by Jay_Davis
No point in arguing. You guys are obviously experts.
I've actually used the same CPU's GM has used for engines for other applications. But no, I must have no idea about their clock and timing capabilities. Give me a break.
FYI: You still don't get the difference in clocks. Then again, apparently neither did the people that built the PDR.
I've actually used the same CPU's GM has used for engines for other applications. But no, I must have no idea about their clock and timing capabilities. Give me a break.
FYI: You still don't get the difference in clocks. Then again, apparently neither did the people that built the PDR.
There is a valid reason for using GPS time for a lap timer as opposed to ECU based "clock" time (or pulse time).
It's like comparing a quartz watch to an atomic clock. The internal ECU time is like the quartz watch, while GPS time is like an atomic clock.
You can try to argue that you don't need the accuracy of the atomic watch, but I'd rather have it than not. There is a reason for races they use quite expensive timing devices.
05-17-2016, 06:53 PM
#23
Drifting
No, I do. You just don't understand their limitations.
There is a valid reason for using GPS time for a lap timer as opposed to ECU based "clock" time (or pulse time).
It's like comparing a quartz watch to an atomic clock. The internal ECU time is like the quartz watch, while GPS time is like an atomic clock.
You can try to argue that you don't need the accuracy of the atomic watch, but I'd rather have it than not. There is a reason for races they use quite expensive timing devices.
There is a valid reason for using GPS time for a lap timer as opposed to ECU based "clock" time (or pulse time).
It's like comparing a quartz watch to an atomic clock. The internal ECU time is like the quartz watch, while GPS time is like an atomic clock.
You can try to argue that you don't need the accuracy of the atomic watch, but I'd rather have it than not. There is a reason for races they use quite expensive timing devices.
That's why everything that uses GPS has a backup system. In the case of the lap timer, the simple, reliable, "less accurate" method gets the job done well within what's required. That's called good engineering.
Last edited by Jay_Davis; 05-17-2016 at 07:23 PM.
05-17-2016, 07:43 PM
#24
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BUT GPS TIME IS NOT RELIABLE SO IT DOESN'T MEET THE REQUIREMENTS FOR THE LAP TIMER.
That's why everything that uses GPS has a backup system. In the case of the lap timer, the simple, reliable, "less accurate" method gets the job done well within what's required. That's called good engineering.
That's why everything that uses GPS has a backup system. In the case of the lap timer, the simple, reliable, "less accurate" method gets the job done well within what's required. That's called good engineering.
I think the reasonable approach of it updating more often is the best solution. That's good engineering, having a fall back for something because you expect it to fail (when it is a system that can be designed not to fail) is bad engineering.
05-18-2016, 07:10 PM
#25
Drifting
No, it is reliable, the issue people have is with the syncing of leap seconds. So they are complaining the time is TOO accurate. They'd like less accurate time without the leap seconds being added.
I think the reasonable approach of it updating more often is the best solution. That's good engineering, having a fall back for something because you expect it to fail (when it is a system that can be designed not to fail) is bad engineering.
I think the reasonable approach of it updating more often is the best solution. That's good engineering, having a fall back for something because you expect it to fail (when it is a system that can be designed not to fail) is bad engineering.
05-18-2016, 08:14 PM
#26
Drifting
I agree with Subw00er... from a software logic standpoint this is the fix. Hopefully they can implement it in the code without too much hassle. It all comes down to how the syncing algorithm works.
05-18-2016, 09:17 PM
#27
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Originally Posted by Jay_Davis
Are you for real? EVERY SYSTEM THAT USES GPS HAS A BACKUP! This includes, aircraft, missiles, bombs, and the car's nav system. The 2 second adjustment is forcing you to see something all the time that could normally happen because you can't guarantee being in contact with the satellites. That two second glitch is even dumber because once it syncs the first time it can adjust it's clock so that in the future it wouldn't only have to account for further drift, but they obviously don't to that either. But then again, use a simple clock and none of this ever happens.
It's not like aviation where everything is there 5 times.
I'm starting to think you are in some sort of field where redundancy is normal, in automotive it's not. In fact everyone tries to find ways to not have redundancy unless something is ASIL D (according to ISO 26262), because then you need to be redundant or diverse in your programming.
I work on stuff like this everyday.
05-19-2016, 08:06 PM
#28
Drifting
When you loose the GPS signal your nav still works. A little less accurate but it still works because it uses other methods of location determination as a backup. Disconnect your GPS antenna and watch.
05-19-2016, 09:53 PM
#29
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Originally Posted by Jay_Davis
When you loose the GPS signal your nav still works. A little less accurate but it still works because it uses other methods of location determination as a backup. Disconnect your GPS antenna and watch.
The purpose of it has to do with skyscrapers in cities blocking GPS between blocks. It's just good enough to meet that, but by no means is it a "backup." Rather a "Gap Filler."
01-30-2017, 07:03 PM
#32
Drifting
As far as I know, there 's still no update which fixes this. Has anyone been able to get this fixed or any further info about an update?
Also, has anyone checked to see if the 2017 version has been fixed?
Also, has anyone checked to see if the 2017 version has been fixed?
02-11-2017, 11:02 PM
#33
Drifting
Looks like there may be an update as per service bulletin 17-NA-013:
https://www.corvetteforum.com/forums...ck-timing.html
Let's hope this fixes it.
https://www.corvetteforum.com/forums...ck-timing.html
Let's hope this fixes it.