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Hi I'm a person who created the android app for windsurfing (WindRace). I thought that the app will satisfy all the needs of windsurfers. The app providers the starting procedure countdown, it records GPS track (GPX is supported) and generates the stats report (with the trace, and charts), provides voice notifications (speed, countdown, sos) and SOS button.Unfortunately the amount of installs is pretty small.
I haven't enough feedbacks to get the good understanding of the needs. Will be happy if someone will try it and give the feedback. The app is free contains some ads (should not be annoying).
Awesome !
I have downloaded it on my phone but im a bit nervous to take my 600 dollar phone out on the water if my waterproof bag gets moisture etc in it.
Can you recommend a cheap and accurate android device that will be sufficient for this incase it is broken by moisture or by impact between my shoulder and the mast on a catapult 
have a look at the GPSLogit thread, we've started a list of phones with their inherent problems.
There are phones available for as low as $30, but I wouldn't recommend them, the biggest problem with some, is when the screen turns off, it goes into some sort of power saving mode. This results in the app loosing the GPS signal, making big gaps in the data, and in some cases big spikes. The next biggest problem is satellite insensitivity, the unit might work OK on your head, but anywhere else will give too much shielding for accurate results. The there seems to be 2 classes of phone, 0.5kts speed resolution and 0.019kts speed resolution. This isn't so important over longer times, but for max speed it has a big effect.
And please if you uncover any more info about phones suitability please add to the GPSLogit thread as well.
We use doppler speed as it's superior to positional calculated speed, It's the doppler speed that has the 0.498 resolution in some phones, we're downloading the .sbp file.
If you do a sort of the data using the doppler speed column, it becomes fairly obvious what the smallest step is between adjacent speeds.
Thank you for trying the app.
GPX file doesn't contain Doppler's speed value (no speed field in the protocol). The generated HTML file have such data. I expect that SDP file also contains the data of such kind.
Try also "Process NMEA 0183" option, it adds the HDOP value (used to exclude data with bad accuracy).
SOS doesn't makes calls. It sends SMS to the specified set of recipients from contact list (see details at windrace.info/#sos)
OK, yes Arseny, the sdp file has doppler speed as well as sdop and hdop values, that way we can get a better idea of accuracy.
I knew there was a reason we didn't use .gpx!
So here's both of them on trackpoints, this makes more sense.
I'll go for a longish bike ride tomorrow, with display off, half way with windrace and logit on, then only logit on.
Good. I've just uploaded the new version #44 (will be available after several hours). The version is focused on Doppler data (in report and realtime). Would be interesting if the report data corresponds to the sdp data from another your app (best 2 seconds for example).
The report now also contains speed resolution (you have mentioned time ago about it).
Very good arseny, you hit the nail on the head!
here's what the GPSLogit data looks like, when I have windrace on for the first half of my ride and off for the return journey.
I have selected the point where I switched windrace off.
The seconds column goes from a nice continuous row of ones to a random jumble of much larger numbers.
The speed graph is full of holes and you can barely make out the return track.
Thanks, mate very helpful. As I don't race, your app isn't all that useful for me, but for somebody who does I can see it would be very good.
For speed sailing it would need to output the doppler data.
here's the windrace report, and the GPSresults report of the logit app.
gpslogit 2s 16.221, 10s 15.081, 100m 14.379, 500m 10.849
windrace 2s 16.138, 10s 14.909, 100m 14.145, 500m 10.812
so windrace is underchanging us a bit.
Will take a bit of trial and error to get the best level of filters. Thought I go "au naturel" but the Xperia's crappy reception lead to speeds being all over the place. I will try the latest Doppler version when I get home. But I like a lot of the features.
Thanks arseny
Hey, I like the html report in the browser.
Yes I updated to the 4.4 version before the cycle ride. and the data in my table above is the doppler data.
Yep, best section is identical for both.
The excluded areas are at the start and finish of the test when the phone had a bit of satellite shading.
As Elmo suggested, I'll put the phone alongside a couple of dedicated GPS units and see if the logit or windrace results are closer.
GPSarpro does a "Trapeze" calculation, but it seems to only apply to the 2s result
windrace 2s 16.138, 10s 14.909, 100m 14.145, 500m 10.812
GPSLogit 2s 16.18, 10s 15.08, 100m 14.33, 500m 10.85, calculated by GPSarpro set to "Trapeze"
I went for another ride today with the Pixie and both the GW52 and GT31, but WindRace's data was all empty, there was all the reports and GPX file, but nothing in any of them.
I'm too busy at the moment to try again, sorry.
