velocity is a function auf GPS-Options?

[ml]

Hello,

a DL1 with 20 Hz
GPS data source (smoothing generally no significant effect)

1: use pre-processed: velocity = 23,5 km/h
integration of longitudinal acceleration is parallel under velocity curve (->2)
2: use post-processed 20 Hz: velocity = 20,6 km/h
integration of longitudinal acceleration = velocity curve
3: use post-processed 20 Hz with PPP: velocity =22,8 km/h
integration of longitudinal acceleration differs in course

What is the right velocity-value?

How do you declare the wide difference between (1) and (2)?
The help-file: "With average GPS reception, speed accuracy is about 0.1mph (or 0.1% if greater) when you are just driving along at fairly constant speed, and about 0.2mph (or 0.1% if greater) during fast accelerations or braking" ????

M.

[Support]

The quoted accuracy is typically for a system with a good GPS signal, however with a degraded signal you can get larger errors.

The speed data from the 20Hz system is particularly good, we've done extensive testing on this and at moderate acceleration levels the error is so small it's very difficult to measure. See this link:

http://www.race-technology.com/wiki/ind ... edAccuracy

What is very strange is that you see a difference between std 20Hz and PPP, typically this should make no practical difference.

If you want to send me the data file (andrew@race.... ) I can have a look, but I suspect it will simply be due to less than ideal GPS reception.

WBR, Andy

[ml]

What is very strange is that you see a difference between std 20Hz and PPP, typically this should make no practical difference.

Yes. I thougt, the accuracy increases from 1 to 3.

I'll send you the File.

M.

[ml]

Andy,
thanks for your review. I put my questions here, because it may be interesting for all.

Which values are good? Which values are good enoug?
GPS vel acc - GPS pos acc - GPS head acc - GPS rtk acc

I noticed that even in good runs with definitely GPS-Lock the diagramm shows ZERO for:
GPS sats, GPS weighted sats, GPS vel flag ??? Is it not designed to be shown in the diagramm?

and a proposal: A message if a run is to short for analysis to downdload the GPS-corrections-data would be helpful.

M.

[Support]

They are all statistical measures and do not have units, they are simply intended to be read as low=good, high=bad. They are all very useful for idenifying problems such as patchy reception, or damaged antenna etc.

The GPS sats, weighted Sats are only available in 20Hz mode. I don't think vel flag is now used - that is legacy only.

WBR, Andy

[ml]

they are simply intended to be read as low=good, high=bad. They are all very useful for idenifying problems such as patchy reception, or damaged antenna etc.

But what is good, what is bad? 1,2,3,4,5...?

M.

[Support]

Generally if you get a GPS acc reading below 5 your signal will be good. If you consistently get higher GPS acc reading then its likely that there is a problem with the GPS reception.