EVO4 + G dash lap times error

[steve everard]

Seem to be getting 0.2 sec per lap difference between G dash and track timing (FRP events.) Mid ohio and VIR ???

Thanks
Steve

[romoman]

Are you using the same location as the timing loop?

[steve everard]

Are you using the same location as the timing loop?

The map on race studio shows start finish at same point race monitor flashed drivers name so I am thinking yes.

[BorkRacing]

Is Evo or track showing you faster?
Where is your transducer and your GPS reviever?

[steve everard]

Is Evo or track showing you faster?
Where is your transducer and your GPS reviever?

Yes showing that we are faster, GPS is 24 inches behind transponder , Nothing has been moved and this has just become a problem

[Lenny T.]

Yes showing that we are faster, GPS is 24 inches behind transponder , Nothing has been moved and this has just become a problem

Steve we were getting same on Jenks car at Mid-Ohio. Aim was always .2 faster.

Lenny

[mikey]

Curious – is this error cumulative/additive? After 10 laps are you two seconds off from official timing? Do you have any correlating video that you can compare time too?
Is the error absolutely repeatable at different times and locations? Perhaps some weird atmospherics interfered with the signal on those days?

[Pi_guy]

My .02 is GPS vs beacon is not as accurate as the GPS result is based on calculations and the other is triggered.
I have gotten slightly different result time by downloading data to different computers with different processors.

[BorkRacing]

GPS is actually military. They can code in an error or a delay for strategic reasons. Earth rotation is 19miles per second. 0.2 error is about 3.8 miles, enough for an incoming warhead to miss its target. Just a thought if this is a new phenomena.

[romoman]

All firmware up to date? Where is the GPS mounted?

Is it a GPS08? In the data, what does it show for the number of satellites and accuracy?

[BorkRacing]

GPS to transducer distance doesn't make a 0.2 difference. At 60mph 0.2 seconds is 17 feet, more than a car length. Now if it was 0.02 then 2 feet will make a difference. If the EVO timer shows you quicker then I suspect it is the timing system which lags. The GPS calculations are made after the signal is recieved so it doesn't matter how long it takes to calculate.

[cooleyjb]

GPS to transducer distance doesn't make a 0.2 difference. At 60mph 0.2 seconds is 17 feet, more than a car length. Now if it was 0.02 then 2 feet will make a difference. If the EVO timer shows you quicker then I suspect it is the timing system which lags. The GPS calculations are made after the signal is recieved so it doesn't matter how long it takes to calculate.

He is asking where it is mounted as in "how well does it see the sky" not relative to the transponder. For example if it is mounted near carbon fiber that block the 'sky' it can really challenge the system to keep up.

[romoman]

In my experience, it's not the system keeping up, but the time delay in the signals to the GPS. The signals will bounce around inside the bodywork before getting to the antenna and cause it to read wrong. The time differences in the sat signals is minuscule, so any small error really matters.

The check of sat count and error usually tells a lot.

[BorkRacing]

Maybe I misunderstood but isn't the EVO showing a faster time?

[Lenny T.]

Maybe I misunderstood but isn't the EVO showing a faster time?

EVO showing faster .2. First time ever happening for us, 2nd year with car. GPS has been mounted on roll hoop since first lap we ran and have not been moved.

[alangbaker]

GPS is actually military. They can code in an error or a delay for strategic reasons. Earth rotation is 19miles per second. 0.2 error is about 3.8 miles, enough for an incoming warhead to miss its target. Just a thought if this is a new phenomena.

That's referred to as "Selective Availability"...

...and the US military turned that off in 2000.

[romoman]

What was the satellite count and error measurement?

[BorkRacing]

What was the satellite count and error measurement?

If the EVo shows him faster then it is not an EVO error, no amount of bouncing around, under or going through glass/carbon or metal will make the signal appear sooner. Plus he said it is on his roll hoop. Source is bad signal reception by AMB.

[Lenny T.]

If the EVo shows him faster then it is not an EVO error, no amount of bouncing around, under or going through glass/carbon or metal will make the signal appear sooner. Plus he said it is on his roll hoop. Source is bad signal reception by AMB.

Can bad signal reception by AMB be corrected ?

[romoman]

If the EVo shows him faster then it is not an EVO error, no amount of bouncing around, under or going through glass/carbon or metal will make the signal appear sooner. Plus he said it is on his roll hoop. Source is bad signal reception by AMB.

In my experience, when the receiver gets a bad signal, it creates all kind of lap timing problems. It will lose position, create short laps, etc. It's normally not like the OP posted, but I haven't heard of an AMB transponder all the sudden going .2 seconds faster either.

[BorkRacing]

In my experience, when the receiver gets a bad signal, it creates all kind of lap timing problems. It will lose position, create short laps, etc. It's normally not like the OP posted, but I haven't heard of an AMB transponder all the sudden going .2 seconds faster either.

The AMB is slower. I've seen it happen many times at many tracks. We time our cars manually and many times the AMB times are off.
But the good news is they are off for everyone and finishes are supposed to be sight, not AMB time.

[steve everard]

All firmware up to date? Where is the GPS mounted?

Is it a GPS08? In the data, what does it show for the number of satellites and accuracy?

# SATELITES IS BETWEE 7 AND 10, ACCUACY 1.24-1.78m

[steve everard]

I compared aim data timing and race monitor(which I assume uses track amb)

I made sure I did not just overlay lap 1 aim with lap1 race monitor because they display differently,

example: lap 3 shows faster on race mon 0.254 then next lap minus 0.255 like it corrected itself. similar on other laps.

[problemchild]

This is not my topic of expertise, but since no one else has identified the exact problem, I will offer a theory.

At some tracks on some days, our aim system misses inserting a break in our data at the finish line. What we often do, is open up the radius on our GPS coordinates, so that there is a larger target for us to drive through and have the the break inserted. When we do this, we are sacrificing some accuracy. So for example, we may have our break inserted at different times, depending on where we are on the track width. If we were on the right side of the track, we would get the break inserted as we entered our target zone. If we entered our target zone in the middle of the track, the insertion may be phased slightly differently. If, for another example, there was a overhanging starter stand, as at M-O, our insertion point may be delayed. With overhanging trees, buildings, fencing, cloud cover, etc, if your quantity of satellite signals are reduced, perhaps some irregularities are occurring,

I would suggest that the AMB was accurate, and your GPS performance was being compromised. Your AIM system is not correcting itself, but reacting to the GPS inputs.

Perhaps your video may offer some clues, but if it was me, I would shrink my GPS zone some, and relocate my GPS antenna to get more satellite inputs.

If my theory is nonsense, be kind. Cheers!

[steve everard]

This is not my topic of expertise, but since no one else has identified the exact problem, I will offer a theory.

At some tracks on some days, our aim system misses inserting a break in our data at the finish line. What we often do, is open up the radius on our GPS coordinates, so that there is a larger target for us to drive through and have the the break inserted. When we do this, we are sacrificing some accuracy. So for example, we may have our break inserted at different times, depending on where we are on the track width. If we were on the right side of the track, we would get the break inserted as we entered our target zone. If we entered our target zone in the middle of the track, the insertion may be phased slightly differently. If, for another example, there was a overhanging starter stand, as at M-O, our insertion point may be delayed. With overhanging trees, buildings, fencing, cloud cover, etc, if your quantity of satellite signals are reduced, perhaps some irregularities are occurring,

I would suggest that the AMB was accurate, and your GPS performance was being compromised. Your AIM system is not correcting itself, but reacting to the GPS inputs.

Perhaps your video may offer some clues, but if it was me, I would shrink my GPS zone some, and relocate my GPS antenna to get more satellite inputs.

If my theory is nonsense, be kind. Cheers!

I checked video and crossing start fin line same point ie not beneath overhang flag station