G force data

ocen

hi Guys,
I am a RC pro android user and i have the below questions:
- How does racechrono pro app extract g force data, is it from the phone or the external GPS?
- if i have a value of 0,85 of Air Fuel ratio, what does that mean?

ocen

aol_of_RaceChrono

- The "lateral acceleration" and "longitudinal acceleration" are calculated values from GPS data

- This is equivalence ratio: https://en.wikipedia.org/wiki/Air–fuel_ratio#Air–fuel_equivalence_ratio_(%CE%BB) . There is also a channel for the "normal" gasoline Air/Fuel ration in graphs which is around 14.7.

ocen

Thank you.
Can i say the position and placement of the phone does not affect Long/Lat values?

aol_of_RaceChrono

Yes, you can say that. But the GPS data needs to be good quality for the lateral and longitudinal accelerations to be trustworthy.

ocen

Thank You so much

DonC

I have an interest in only the forward acceleration. Can I get the G-force values from the log files?

aol_of_RaceChrono

@DonC look at the longitudinal acceleration (which is calculated from GPS data). Should be pretty accurate as long as your GPS is.

DonC

Unfortunately, I lost or delete the sessions on my tablet. I will need to record a est session to look at the log. Which file has the G force data? I will be testin on a straight "track" or road.

At the least, you could simply watch the video with G force overlay, and stop the video at the times you want to record the G-force.

DonC

If you have the NMEA data, is it hard to calculate speed and G-force using a spreadsheet program?

aol_of_RaceChrono

It's hard. But you can re-import an NMEA file in RaceChrono for Android. First copy the file to /Android/data/com.racechrono(.app|.pro)/files/input/ . Then enable Settings > Expert settings > Experimental devices. Then add GPS device with type "NMEA input", and select the file you've just copied.

DonC

Thank you. On my device, it's called, "NMEA file (for debug)" .

If you already use the Dual 150 GPS device, why would you add the "Dual XGPS 150/160" as a GPS receiver? Does it add any extra features?

aol_of_RaceChrono

@DonC I don't understand what you mean. There's no other way to use an external GPS with RaceChrono on Android, than adding them in RaceChrono settings...

DonC

One of the GPS devices you can add is called Dual XGPS 150/160. Maybe it just refers to either, with no difference in the positioning data, even though the 160 GPS has more capability than the 150, like the 10 Hz updates.

aol_of_RaceChrono

@DonC, yeah you should use the "Dual XGPS 150/160" option when you configure your Dual XGPS 150 with RaceChrono. In Android, only difference to "Bluetooth GPS receiver" option is the update rate configuration for 150. On iOS there's other differences too. It can detect between 150/160 so each device is configured accordingly.

DonC

Can you explain some more about the " update rate configuration for 150" ? Is it a better rate or accuracy?

aol_of_RaceChrono

@DonC It tries to configure the Dual XGPS 150 to 5 Hz (instead of standard 1 Hz). Works on my 150A at least.

DonC

Does the GPS150 stay i 5 Hz mode after you leave RC?

aol_of_RaceChrono

I havent tried