Speedo and avg speed via OBD

Any discussion on using LapTimer. Please use this forum in case you need guidance on how to use LapTimer or perform a certain operation
Post Reply
User avatar
PitrsRS
20 or more Posts ★★★
20 or more Posts ★★★
Posts: 156
Joined: Wed Jun 25, 2014 9:43 am
Location: Prague, Czech Republic

Speedo and avg speed via OBD

Post by PitrsRS »

Hi Harry,

I want to ask about one thing. Sometimes I´m using speedo because it can measure avg speed. It´s usefull on roads in radar controled sections (point to point measuring). But I found a little "bug". App can´t measure avg speed with only OBD speed (in tunels). It needs GPS for it.

It´s a normal behavior?
2016 SEAT Leon CUPRA 290 ST

HLT Grand Prix (Android) + OBDLink LX BT + XGPS160 + GoPro 11 Black + GoPro 7 Black
User avatar
Harry
Site Admin
Site Admin
Posts: 10518
Joined: Sun Sep 12, 2010 10:32 am
Location: Siegum, Germany
Contact:

Re: Speedo and avg speed via OBD

Post by Harry »

Avg speed is derived from distance driven and time required, not some integration of actual speed values. Something like this could be done, although it requires some numeric tweaking due to the influence of data and calculation inaccuracies. Not trivial.

Harry
Image Image Image Image
User avatar
Harry
Site Admin
Site Admin
Posts: 10518
Joined: Sun Sep 12, 2010 10:32 am
Location: Siegum, Germany
Contact:

Re: Speedo and avg speed via OBD

Post by Harry »

PS As long as the tunnel is straight, you should see proper values after leaving the tunnel again.
Image Image Image Image
User avatar
PitrsRS
20 or more Posts ★★★
20 or more Posts ★★★
Posts: 156
Joined: Wed Jun 25, 2014 9:43 am
Location: Prague, Czech Republic

Re: Speedo and avg speed via OBD

Post by PitrsRS »

Ah, thanks for explanation. The tunel, where I needed most, is complicated, there are changes in elevation, corners etc. We have there 5-6 measured sections and sometimes speed limit is changed from 70 to 50 or 50 to 70 during passing (it depends on how heavy actual traffic is at the moment)

But. Distance could be calculated from speed and time, and these 2 values we have.
Attachments
Výstřižek.JPG
Výstřižek.JPG (110.75 KiB) Viewed 1859 times
2016 SEAT Leon CUPRA 290 ST

HLT Grand Prix (Android) + OBDLink LX BT + XGPS160 + GoPro 11 Black + GoPro 7 Black
Post Reply