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.

Select to expand quote

izymiester said..
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

Thank you for downloading. I understand your concerns regarding 600 dollars.

Both my android devices have IP67 protection but I prefer extra safety.

I use S5 Mini with the waterproof bag on the neck under the t-shirt (lycra). I've ordered a set of different waterproof bags and use one which seems safer to me :)

Sometimes I use Xperia Go ST27i without waterproof bag to hear the voice better (when the water is not salty enough). I place it in the pocket on the shoulder of the jacket for windsurfing.

Select to expand quote

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.

As I know the Android platform provides an ability to avoid the sleeping with power saving mode on the programmatic level (even if the screen is turned off).

Select to expand quote

The there seems to be 2 classes of phone, 0.5kts speed resolution and 0.019kts speed resolution. And please if you uncover any more info about phones suitability please add to the GPSLogit thread as well.

I've went throught the "GPSLogit phones speed resolution" and the meaning of the speed resolution is still unclear for me. I.e. it is unclear how the speed resolution value is evaluated for the device?

I can also say that Android allows to receive the GPS data using different ways. One of them is the reading of the NMEA protocol which provides data right from GPS chipset (more different data is available for GPS track).And the second one is the receiving of the GPS locations on the Android's platform level. Sometimes I think that Android corrects the data received via NMEA. I'm going to record the track using both data sources simultaneously to check that assumption.

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.

Select to expand quote

arseny said..
>>>

As I know the Android platform provides an ability to avoid the sleeping with power saving mode on the programmatic level (even if the screen is turned off).


>>>>>.

Are you saying you know how to turn the power saving mode of in "settings" or do you need to "root" the phone and get into the main software?

Because I have "power saving mode" turned of in my alcatel pixie 3 and it still has big gaps in the data when the display turns off.

Select to expand quote

decrepit said..
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.

Good. Now I see the priorities. I'll add stats about doppler speed (GPS speed in the app) to the track report. I will show this of speed on screen and will configure the notifications (sound and voices. Thank's for the clarification of the doppler speed resolution. I will display the value right to the report (it is easy).

The speed field is absent in GPX format. Seems that it's the reason of the vendor specific binary formats like .SBN (.SBP & .UBX). I need a time to see if I will be able to produce an output file in such format.

Select to expand quote

decrepit said..

arseny said..
>>>

As I know the Android platform provides an ability to avoid the sleeping with power saving mode on the programmatic level (even if the screen is turned off).


>>>>>.

Are you saying you know how to turn the power saving mode of in "settings" or do you need to "root" the phone and get into the main software?

Because I have "power saving mode" turned of in my alcatel pixie 3 and it still has big gaps in the data when the display turns off.

Actually I was writing about the ability for the apps (i.e. the app can ask android to not switch device to the power saving mode even when screen is off). My app uses that feature.
At the same time I can assume that the cheap device could have bad drivers which breaks the described function.

Select to expand quote

arseny said..

decrepit said..

arseny said..
>>>

As I know the Android platform provides an ability to avoid the sleeping with power saving mode on the programmatic level (even if the screen is turned off).


>>>>>.

Are you saying you know how to turn the power saving mode of in "settings" or do you need to "root" the phone and get into the main software?

Because I have "power saving mode" turned of in my alcatel pixie 3 and it still has big gaps in the data when the display turns off.

Actually I was writing about the ability for the apps (i.e. the app can ask android to not switch device to the power saving mode even when screen is off). My app uses that feature.
At the same time I can assume that the cheap device could have bad drivers which breaks the described function.

That would be very good if you can solve that one, it would make a cheap phone useable.

Select to expand quote

decrepit said..
That would be very good if you can solve that one, it would make a cheap phone useable.

Its called a "wake lock"... the Android API has support for it.

Select to expand quote

decrepit said..
That would be very good if you can solve that one, it would make a cheap phone useable.

You can do the experiment with my app on your alcatel pixie 3 :) If the gaps will be missing in the recorded report or GPS track then the problems in the app you are using. Let me know if you'll meet problems with my app.

Select to expand quote

arseny said..

decrepit said..
That would be very good if you can solve that one, it would make a cheap phone useable.

You can do the experiment with my app on your alcatel pixie 3 :) If the gaps will be missing in the recorded report or GPS track then the problems in the app you are using. Let me know if you'll meet problems with my app.

Good idea, will do.
Hmmm maybe I won't, why does the app need to send SMS's read my contacts, and have full network access, this phone has no sim card and is set to airplane mode

ok so tried it, but where does it store the data?

Select to expand quote

decrepit said..
ok so tried it, but where does it store the data?

OK, I now see why the app asks for phone and contact access, it's got an SOS function, to call emergency numbers with co-ordinates, great idea!

I've now added and SD card to the Pixie, so WindRace can store it's files.

And I've had very interesting results running both apps together.



Strange the apps give different results, they're both working of the same set of data, why is this so?????
Maybe the phone isn't fast enough to handle both apps at once?

And on this short test, there doesn't seem to be any holes.

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).

ok I'll update the app tomorrow. thanks for your trouble.

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.

Select to expand quote

decrepit said..
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.

How does it compare to the accepted GT's as Logit tended to come up with results a bit high anyway?

good point Alby, I'll try it out later.

Select to expand quote

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.

Decrepit thank you. Your comments made the app better.

There is an option to the "GPS settings" to use Doppler data ("GPS data priority"). And the option it is turned on by default. The Doppler speed and direction are shown by default on the screen ("GPS speed" is the Doppler speed). The stats (2s,10s,100m..) is displayed for both speeds (Doppler's and positional) in the separate tables of the report since the version 44. Have you updated the app before test?

The difference in the stats could be also related with the GPS filters which are configured in GPS settings. Those filters are excluding the bad locations from the stats (in the report). The data of such bad locations is also not shown on the screen. And the speed of such bad location isn't pronounced at realtime (you can turn off the voice and sound notifications). But the bad location is included into the GPX file for analyze by the other tools.
If you will open the generated html report and will "Build GPS track and charts" then you'll see the excluded points. Those points are in the small red circles on the map. And you can pick the point to see its details.

The sections of the best speed (2s,10s and etc) are shown as the separate layers on the GPS trace (can be turned off/on). Are those best sections have similar positions like the best sections in GPSLogit?

Sorry for troubling, I appreciate your participation.

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.

Select to expand quote

yoyo said..
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

sony xperia z3 compact has a shocking gps , struggles even in the car and in a city.

Jogging around an oval its spiking all over the place.

Select to expand quote

decrepit said..
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.

Hmmm

WindRace considers 3 locations for the best 2 seconds (11 locations for best 10 sec and etc.) in common case when there is a 1 sec delay between GPS locations i.e. the best 2 seconds are calculated as the average value of GPS speed for 3 points. May be GPSLogit calculates the average for two points only (and 10 points for best 10 sec...). It could be the reason of the difference.

Another reason could be in the arithmetic algorithm. The best value is evaluated right during the recording. The app is adding the influence of the new location's speed to the average value and removing the influence of the obsolete location in the chain. Such a way saves processor time especially for such cases when the amount of locations in chain is significant (like the best n. mile). But it can give a small error in result.

Would be nice to understand the real cause of the difference (I think that the first case is the best candidate). Can you write the values of GPS speed for 3 points of the best 2 sec?

Select to expand quote

izymiester said..

yoyo said..
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

sony xperia z3 compact has a shocking gps , struggles even in the car and in a city.

Jogging around an oval its spiking all over the place.

Actually I met problems with GPS in a city. Seems that the buildings are significantly affecting to the signals quality. You can also meet the similar problems in the mountains. And I also found that neopren also breaks the GPS quality.

I.e. the GPS quality should be better on the water (or in the field) especially on a sunny day.

Select to expand quote

arseny said..
>>>>>

Hmmm

WindRace considers 3 locations for the best 2 seconds (11 locations for best 10 sec and etc.) in common case when there is a 1 sec delay between GPS locations i.e. the best 2 seconds are calculated as the average value of GPS speed for 3 points. May be GPSLogit calculates the average for two points only (and 10 points for best 10 sec...). It could be the reason of the difference.

Another reason could be in the arithmetic algorithm. The best value is evaluated right during the recording. The app is adding the influence of the new location's speed to the average value and removing the influence of the obsolete location in the chain. Such a way saves processor time especially for such cases when the amount of locations in chain is significant (like the best n. mile). But it can give a small error in result.

Would be nice to understand the real cause of the difference (I think that the first case is the best candidate). Can you write the values of GPS speed for 3 points of the best 2 sec?

Spot on Arseny, GPSResults by default uses 2 points, the difference is about right for you using 3. Real speed also uses 3 by default, but I don't have that on this operating system.
I'll see if I can get GPSResults to use 3 points.

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.

Select to expand quote

decrepit said..

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'm too busy at the moment to try again, sorry.

If you will get time then please write the GPS speeds of the WindRace's 3 points for best 2 sec.
Thank you for your feedback.