Wrong acceleration data

Derro

v4.2.4. On previous version my acceleration figures varied between about 0.7G and 1.2G (Lateral) or 0.6G and 1.1G (Longitudinal). In the latest version lateral show as 4G to 5G ( I'm not that accomplished!) tho' longitudinal is still about the same. Why?
Also, I could see the choosen parameter superimposed on the speed graph but not now - only the maximum figure for the lap is shown on the summary screen. Why?
Finally, I use Qstarz 818XT with my Sony Z3 and it provides (or used to) all the information I want from the occasional track day. Is there any avantage in installing the Pro version other than helping with development costs (which I don't mind).

aol_of_RaceChrono

I checked and the feature looks to be working OK in the latest version, but there is something to consider: The accelerations are calculated from the GPS trajectories, it might show 4-5G if the GPS data is not perfect. I will have this smoothed in upcoming versions, so it will fix some of the spikes coming from the GPS.

The Pro version has some big advantages: 1) Video recording, analysis and export. 2) Time delta display in live timer (predictive lap timer) 3) Analysis graphs are scaled based on position, so comparison lap is always in sync. 4) Time delta and Time gain channels for graphs, you can see accurately where you lost/gained time.

Derro

Thanks for the quick response. When I superimpose recent acceleration figures on the speed graph I can see how ragged the acceleration plot is. The spikes probably relate to the extreme acceleration figures. However when I check track day records from May 2015 the graphs are smoothed. (Same phone and GPS receiver). An older phone (but same GPS) still has RaceChrono V4.0.9 and these graphs are also smoothed.

(I'm never likely to use the extra features of the Pro Version, but I like what you do for free, so will buy the Pro.)

aol_of_RaceChrono

I can take a look at your sessions, just share them to tracks(at)racechrono.com using the share button on top of the session overview. It's most probably just the GPS data quality, because the accelerations go choppy really quickly when data quality goes down.

Derro

Done, or least I think that two emails with data have been sent. They are for sessions SMSP on 7 May and 12 August.
(I purchased Pro not because I'll ever use the features but because I think that you a fantastic job in the free version and answering questions from novices (though not age) like myself.)

aol_of_RaceChrono

Thank you for supporting my work I will look at the sessions shortly and give my comments.

aol_of_RaceChrono

Hi, finally had time to look at the sessions. The "smooth" session was recorded at 1 Hz GPS update rate and the second one 10 Hz. This is the reason the acceleration calculations are smooth vs. not smooth. Upcoming data averaging will fix this.

Derro

Thanks for the analysis. Selection of the 1Hz update rate may have happened when I slid the Qstarz GPS unit into the pouch mounted on the bike. I guess that I was a little more careful in the following months. Looking forward to the new release.