[Ovmsdev] Strange issues with Car GPS accuracy.

Fri Jul 14 12:30:42 HKT 2023

Hi Mark,

I have been running without the GSM board for a couple of weeks now and
have had no issues with GPS.  As with my last email, before doing this, I
had tried putting the antennae in the back seat with no change to the
occurrence of the issues.

I had tried with the GSM board in, but the power to it off (power cellular
off) but it was still giving me problems.  I tried with and without the HUD
display plugged in and again, it still gave me problems.

So far the only thing that has worked is removing the GSM board.  I guess I
can try putting it back in and see what happens.  I really would like this
to function with the GSM board since I would like it to function without
access to the wifi!  (For the moment, I can cope with it).  Any help in
diagnosing this would be greatly appreciated.

//.ichael

On Mon, 3 Jul 2023 at 14:15, Michael Geddes <frog at bunyip.wheelycreek.net>
wrote:

> 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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>>>>
>>>> --
>>>> Michael Balzer * Helkenberger Weg 9 * D-58256 Ennepetal
>>>> Fon 02333 / 833 5735 * Handy 0176 / 206 989 26
>>>>
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