GPS issues in karting

[llokf1]

Hello everybody,
I tried the trackAddict app for Android using the internal GPS for a few karting runs, but it turned out to be totally unusable due to the low GPS accuracy with constants jumps in position, crossing the path itself, etc . I had the phone attached to my chest with a "harness".
Is it normal this low accuracy using the internal GPS? Could it be the position of the phone (attached to my chest) a reason for it?

In case of buying an external GPS what would be the cheapest but still reliable option for karting? I have read good reviews about Garmin Glo, is it working fine with the app?
Thanks!

[Weston@HPTuners]

Unfortunately, attaching the phone (or GPS receiver) to your body, or placing it in a pocket, very commonly has poor results. Your body may be obstructing the GPS signal, but perhaps more importantly you would definitely be moving around relative to the vehicle, causing the GPS signal to have continually variable paths, obstructions, and reflections off of nearby metal items. It seems to be difficult for a GPS to filter out errors when its position is rapidly changing relative to the interference or reflection sources around it.

An upgraded GPS unit can usually do better with this than a smartphone, but ultimately the phone / GPS should always be securely attached to the vehicle itself. The two seemingly most popular upgraded GPS units for our users are the XGPS160 from Dual Electronics (work on iOS or Android), and the Qstarz BT-Q818XT (Android only; might do a little better in some motorsports conditions). Both are Bluetooth and provide data at 10 Hz, have great precision and accuracy, and also handle difficult reception conditions better than many phone GPS'es will.

I should also mention that if this is at an indoor karting track, then GPS reception will likely always be a problem. But outdoor karting is a better situation for GPS, and many users have had success with that.

[llokf1]

Thank you for the answer.
Well, since a kart is quite tight, when driving it you don't move much your body around relative to the kart. So i think it should be more like my body obstructing the signal and avoiding a good reception and accuracy. My test was outdoor karting.

Is there any special reason for not recommending the Garmin Glo gps for your app? I am asking because It supports also GLONASS satellites whereas Qstarz BT-Q818XT doesn't . So i think Garmin Glo could be a better option.

[Weston@HPTuners]

Even though you don't move much in a kart, it doesn't take much to potentially shift the signal around when in such close proximity to items that would obstruct or reflect the signal, especially if it didn't have a very big or clear line-of-sight to the sky to begin with.

There's no reason against the Glo for Android users, as I believe it also is able to provide us NMEA-0183 data over Bluetooth. The BT-Q818XT appears to be more widely known and more commonly used for this type of apps, due to it being manufactured by a motorsports data company and having been proven to be quite good for high speed race track use (I've seen other GPS'es that did not respond as well to fast changes in speed or direction). However, we don't get the actual NMEA data for either of them on iOS (and the BT-Q818XT isn't compatible with iOS at all), so the XGPS160 is a better fit for iPhone/iPad users, as TrackAddict for iOS has special code to be able to get its raw NMEA data at 10 Hz.

Good GPS-only hardware has proven its ability to work very well on track, so support for other positioning systems like GLONASS, Galileo, and Beidou, is not necessary. Those *might* help if the unit has good logic to merge it with the GPS data and then provides unified NMEA samples, but if it's provided separately in the NMEA data, then that wouldn't be utilized. On the other hand, if a GPS+GLONASS device wasn't providing very good data, the first thing I'd suggest after improving its signal reception conditions, would be to try disabling the GLONASS functionality.

[Psymon]

I've tried all kinds of way but it's just too difficult to mount a phone securely onto a kart; and the GPS sensor on the phone is just not accurate enough for such small distance.

For Karting, I get much better result with a GoPro Hero 5, mounted directly on the kart. Then use Race Renders on a computer instead to extract the GPS data from the GoPro video files. There's no advantage of using TA on a phone for karting since the sensors on the kart are not paired with the phone.

I still use TA for cars where I pair the ODB2 adaptor to the phone.

[lzzl551]

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[mvtedeschi]

What is he using to attached the phone in the steering wheels?