Chart speed not zero at standstill

[GoogleCodeExporter]

What steps will reproduce the problem?
1. Start recording
2. Switch tochart view
3. Come to stop after moving, pause, and begin moving again

What is the expected output? What do you see instead?
Chart showing speed of 0 mph. Shows 18-20 mph

What version of MyTracks are you using? On what version of Android? On what
phone?
1.1.13
2.3.3
DROID X, Verizon 4.5.605

If possible please provide a log.  Either upload here or send to mytracks-
support@google.com.
Detailed instructions can be found here:
http://code.google.com/p/mytracks/wiki/HowToReportErrors

Please provide any additional information here:

Original issue reported on code.google.com by dynamica...@gmail.com on 27 Jan 2012 at 5:53

[GoogleCodeExporter]

[deleted comment]

[GoogleCodeExporter]

Believe I have the same issue
After initially starting to record a track, chart value never drops to 0 speed, 
no matter how many times you come to a stop, including at the "finish" point
graph shows varying speed throughout, and shows the initial deaccelaration when 
coming to stop but then flatlines at varying values (including higher than some 
steady speeds recorded) is it possibly connected to not recording a new point 
when position doesn't change, hence not being able to calculate when speed is 
zero.

my tracks version 2.0
android 2.3.4
sony ericsson xperia mini pro (not x10)

Original comment by williams...@hotmail.com on 4 Sep 2012 at 11:51

[GoogleCodeExporter]

Hi Williams:

You are right. When stationary, no more locations are recorded. On the 
ChartView, it shows the smoothing average over the last 25 recorded locations.

Not sure the solution though, we don't want to waste space by storing lots of 
stationary points. We also don't want to show the latest location speed 
(without smoothing it out).

Jimmy

Original comment by jshih@google.com on 6 Sep 2012 at 11:14

[GoogleCodeExporter]

Zero speed is unique, though. Only two points (initial and final
position and time) can represent any number of zero-speed points
because the object is (by definition) stationary. The definition of
"zero speed" may need to be calibrated for most GPS receivers - I
often see 1 or 2kt of wandering when my unit is sitting completely
still.

Donald.

Original comment by dhloc...@gmail.com on 6 Sep 2012 at 11:52

[GoogleCodeExporter]

Hi Jimmy and Donald,
Thanks for both of your replys. 
In response to Donald, I fully understand the uniqueness of the value 0 and am 
aware of the complex maths regarding 0.
I am not worried by a small amount of error but using tracks whilst on my 
motorbike when at rest i.e. 0 speed my chart showed 55km/h!!! this is not an 
acceptable error ;-). I have attached some screen shots to highlight the issue. 
In response to Jimmy, if you are trying to accurately record your motion with 
respect to time then stationary points are possibly as valid as the moving ones?
Possible solutions :-
Could this be a user option "store location when stationary" yes/no and leave 
it to the user to choose the amount of data stored. 
Or when stationary, record 25 locations then stop recording.
Or have chart view smooth over 25 locations, unless speed is approx 0 in which 
case it takes just last value.
See attached screen shots, and note the flat lines at 17.09-19.04 and the final 
speed from about 29.00 till finish recording.
I have to say that i generally love the mytracks app and have ditched endomondo 
in favour of it.
Thanks again, it is really appreciated the time spent to look at these problems.

Original comment by williams...@hotmail.com on 7 Sep 2012 at 8:07

Attachments:

• screenshot_2012-09-07_0834.png
• screenshot_2012-09-07_0835.png