[Ovmsdev] Strange issues with Car GPS accuracy.

Mon Jul 3 14:15:07 HKT 2023

HI Mark,

I have an Ioniq 5.

I have no idea if it's related to the CAN bus. I have had lots of
hypotheses but nothing has stuck.  I know at one point polling too fast
seemed to  totally freeze out the GPS updates from getting to the Maps UI
and from Android Auto.  But I'm suspecting there is other things going on.
I  tried it with the GSM switched off on startup and it was still happening
(GPS Drift).
The antennae cords are quite long, so I tried placing then on opposite rear
seats, which should be far enough away, and it was still happening. I
rearranged cords so they weren't next to each other.  And anyway I TRIED
SWITCHING GSM OFF.

I really didn't expect removing the daughter board to work btw.  I swapped
back to my old OVMS and the drifting went away, so I removed the GSM module
from the new OVMS and was really not expecting any difference, as I thought
I'd eliminated that module by turning the power off!!  I was totally
expecting it to be an issue on the main OVMS board.

More clutching at straws: At one point I noticed that both the GSM and GPS
antennae had come slightly loose at which point I tightened them.

Any other thoughts would be welcome.  I really would like to have the GSM +
GPS back on board.  I can use an external GSM to wifi extender ... but GPS
would be harder.

//.ichael

On Mon, 3 Jul 2023 at 10:33, Mark Webb-Johnson <mark at webb-johnson.net>
wrote:

> Michael,
>
> I don’t see how that board is related to CAN bus at all. It does have an
> incremental power draw, so could affect 12V supply (but unlikely).
>
> Far more likely is the antenna placement and direct RF interference. Where
> did you place the two OVMS antennas (GPS and GSM), and are they anywhere
> close to the original GPS antenna in the car? What is your car type?
>
> Regards, Mark.
>
> On 2 Jul 2023, at 4:24 PM, Michael Geddes <frog at bunyip.wheelycreek.net>
> wrote:
>
> It's definitely something to do with the daughter board for GSM+GPS since
> I've take it out and it all seems fine!!!  I have the OBD2ECU updating the
> speed at an acceptable rate too.
>
> //.ichael
>
> On Mon, 19 June 2023, 10:02 pm Michael Geddes, <
> frog at bunyip.wheelycreek.net> wrote:
>
>> *sigh* I'm now at the point where my OVMS is next to unusable because of
>> the GPS interference issue.  I switched back to my old ovms unit (no GSM
>> daughter board and the external power doesn't work)... And the problem went
>> away. Even with the faster polling. So it seems something is possibly wrong
>> with the OVMS hardware itself.. Maybe some noise on the can bus is playing
>> havock? It's most peculiar.
>>
>> It might also make sense of something I'm seeing on the HUD which is that
>> it periodically stalls and resets.
>> I guess I should move the daughter board across to check out that.
>>
>> Michael
>>
>>
>> On Mon, 29 May 2023, 4:06 pm Michael Balzer, <dexter at expeedo.de> wrote:
>>
>>> Michael,
>>>
>>> if the module affects your car's builtin navigation system, I think that
>>> points to some EM interference. While the module has passed the EM tests
>>> for certification, it still emits some EM noise, and some devices are more
>>> sensitive to this than others. There also may be a satellite outage
>>> affecting Australia currently, that adds to the sensitivity.
>>>
>>> You could try to selectively switch off Wifi and the modem when the
>>> issue occurs, to see if one of these cause it.
>>>
>>> If not, you could try reorienting and replacing the module in the car,
>>> especially if it's very close to the nav system's GPS antenna.
>>>
>>> Regards,
>>> Michael
>>>
>>>
>>> Am 27.05.23 um 10:07 schrieb Michael Geddes:
>>>
>>> Latest: I changed the startup vehicle to None and turned off the
>>> mobile.  Still getting drifting vehicle GPS until I unplug the OVMS.
>>> Hardware issue? Does anybody have any clues?
>>>
>>> Michael
>>>
>>> On Sun, 21 May 2023, 11:41 am Michael Geddes, <
>>> frog at bunyip.wheelycreek.net> wrote:
>>>
>>>> Hi all,
>>>> I'm having a bunch of weird things going on which seem correlated to
>>>> having the OVMS running.  I'm not convinced of causation yet.
>>>>
>>>> My car's Nav system is drifting out majorly (like by >100m) and then
>>>> seems to stay out.  This causes major distractions as the nav system keeps
>>>> giving me warnings about going down one-way roads and it makes the
>>>> navigation 'interesting' to use.
>>>>
>>>> I also noticed that Android Auto location was frozen in one place, so I
>>>> assumed this was coming from the car - or meant to be anyway.  I reduced
>>>> the polling rate (new work I'm doing) slightly and this freezing no longer
>>>> happens. (To 3 speed queries per second).  But the drifting out on the
>>>> Navigation  still happens... but then not on AA!? Very very weird.
>>>>
>>>> If I unplug the OVMS from the OBD port (as I'm driving) it seems to
>>>> (but not immediately - after a minute or so) correct itself.  It's hard to
>>>> confirm this is directly resulting .. but it seems to be?
>>>>
>>>> I turned off my ECU2OBD which should mean that it is resorting to 1 per
>>>> second POLL with a low throttle value.  I'll run with some logs to make
>>>> sure this is what is happening.. but it still seems that this hasn't
>>>> stopped this issue from happening.
>>>>
>>>> I've tried turning the GSM power off. No result.
>>>>
>>>> Another note: I seem to have stopped getting anything near regular
>>>> updates from the OVMS GPS. Every now and again it gets a successful change
>>>> come through.  Still working on diagnosing that.. maybe it's related?
>>>>
>>>>
>>>> Any thoughts / help would be useful.
>>>>
>>>> //.ichael
>>>>
>>>>
>>>>
>>>>
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