Badelf gps delay

Discussion related to external and internal GPS / GLONASS / Galileo / BeiDou sensors
shadowpuck
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Badelf gps delay

Post by shadowpuck »

Is there a general recommendation for the sensor delay setting for the lightning version of the badelf gps?

And would the correct setting to adjust be the external gps sensor? Or, is it consumer level gps?

My external gps sensor delay setting seems preset at .7 but I’m struggling with speed not matching the video. Everything else on video seems synced.
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Harry
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Re: Badelf gps delay

Post by Harry »

The delay applied for the BadElf is the external GPS sensor. But: in case data and video do not match start with adjusting Overlay Synchronization / Video. It is the only delay applied „after the fact“. All others are applied during recording.

For more information, please see this FAQ: viewtopic.php?f=39&t=4940

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Re: Badelf gps delay

Post by shadowpuck »

hi harry! thank you for the quick reply!

i think all of my laps are showing the same issue. so after looking at the adjustment steps that's how i got curious about the sensor delay itself.

it also seems to perhaps start being a problem on a specific part of the lap, but, i haven't confirmed that yet. i just noticed the speed is not synced to the video - you can, for example, hear me accelerating or braking and the speed is not on time. everything else looks just fine.

i also took a look at the video sync setting mentioned in the article but any value entered either made no difference or made the matter worse....

i can post a example if that would help explain better; however, i expect (based on my searching here and the existence of the faq) that this has been a common problem.

i did attempt to adjust the session as noted in the faq as well - but, that didn't seem to change. i did note that when i first tried to adjust the video the first image it brings up does not show the finish line - i had to move it back some steps to see the finish line. that didn't appear to change anything though - but, i might not have done the adjustment correctly.
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Re: Badelf gps delay

Post by shadowpuck »

i forgot to add:

i'm using an iphone 8+ and its internal camera only, with the lightning connector bad elf gps. so, not a complicated setup. the phone is mounted to my windshield and seems to get good gps coverage.
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Re: Badelf gps delay

Post by Harry »

In case the sync changes within a lap, you may have linked the wrong one? Just in case you played with relink and sync points…

In case things get worse after a change, you need to change the delay the opposite direction. In case video / audio is behind data, increase the overlay sync setting. And vice versa.

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Re: Badelf gps delay

Post by shadowpuck »

i think its all laps - actually. the video/audio sound fine, everything else looks to be in sync - timing, track location, g-force, etc. it's the displayed speed that is off. i think the speed is right, but the timing is not.

i need to try and figure out is the sync ahead or behind - my honest feeling is the speed is behind the video...

i had tried the video overlay adjustment but it goes from 0 on up but anything from 0 on up just makes it worse.
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Re: Badelf gps delay

Post by Harry »

In case you need to go to zero or below, there is something wrong. Instead of decreasing video sync, you can increase all other delays. The effect will get available for new recordings only.

Btw. GPS Speed is always a little late. This is due to the Doppler effect used to measure speed. OBD speed will be more instantaneous.

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Re: Badelf gps delay

Post by shadowpuck »

harry - yeah, good point. i can tolerate a bit off sync due to doppler as you mentioned. it's just nice if i can get it closer.

that's how i ended up at asking about the gps delay in the settings. it's set at .7 (i did not set that) - and was curious if there was a known good range for badelf or if i'll just have to experiment. unfortunately, my car is too old for obd.

would using calculated speed help any for future recordings?
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Re: Badelf gps delay

Post by Harry »

Not recommended. The 0.7 delay is a good starting point for 5 and 10Hz sensors. But the delay time depends not only on update rate, but on the signal runtime and processing time too. I usually recommend to not fiddle with these. One can get addicted to optimizing sync. :-D

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Re: Badelf gps delay

Post by shadowpuck »

yes - understood....went through that type of thing recently with my triple screens for simracing....

i may try the calculated next time around and see if that helps. it's definitely enough out of sync that its easily noticed....i would think my setup is simple enough - the phone is only used for this (so, it's not my primary phone) - everything is removed except laptimer, basically its a fancy ipod at this point...
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