Forums > Windsurfing   Gps and Speed talk

Alternative to the GT-31

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Created by Tony Wills > 9 months ago, 11 Feb 2015
kato
VIC, 2469 posts
23 Apr 2015 10:13PM
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elmo said...
Good water proof/resistant phone covers

www.lifeproof.com/en/


These are very good. I use these and a custom made case for my phone and external battery. Works very well so far with a external ear phone jack as well.Can take calls while windsurfing. Not that I'd want to

decrepit
WA, 9171 posts
23 Apr 2015 8:44PM
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sausage said..
Did a little test on the school run this afternoon but damned if I can find the recorded file in my phone. Does anyone know where I can locate it or doesn't this trial version save the files after turning app off?


Yep file is saved, found mine in the phone's own memory in the gpslogit file.

decrepit
WA, 9171 posts
23 Apr 2015 8:54PM
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kato said..

elmo said...
Good water proof/resistant phone covers

www.lifeproof.com/en/



These are very good. I use these and a custom made case for my phone and external battery. Works very well so far with a external ear phone jack as well.Can take calls while windsurfing. Not that I'd want to


This is probably what I needed today, took my phone for a wallow, but couldn't see anything through the ziplock bag and paquamidi.
Unfortunately the wind died as I was working my way upwind and I only managed 10knots.
so these are my results.
gt31 logit
2s, 10.29 10.08
5x10, 7.68 7.78
1hr .45 .39
nm 4.13 4.13
alpha 2.93 2.88

JHdeBruin
32 posts
24 Apr 2015 7:02AM
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Tested it with a Sony Z1 Compact...

Sessions details here:

www.gps-speedsurfing.com/default.aspx?mnu=forum&forum=2&val=82653

GT-31 Logit
2s 27.05 27.7
5x10 25.72 25.42
1hr 13.43 12.98
nm 21.83 21.34
alpha 17.04 16.76

sausage
QLD, 4796 posts
24 Apr 2015 10:26AM
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decrepit said..


sausage said..
Did a little test on the school run this afternoon but damned if I can find the recorded file in my phone. Does anyone know where I can locate it or doesn't this trial version save the files after turning app off?




Yep file is saved, found mine in the phone's own memory in the gpslogit file.



Okay I finally found it (after downloading file explorer app) but does anyone know how to export the file from phone to open it in GPS programme (file is stored on SD card of phone from what I can make out)

seanhogan
3033 posts
24 Apr 2015 8:47AM
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with the phone connected to the computer via usb you should see the file

prob something like : computer/phone/sdcard/gpslogit/your file

then it's just as usual with a gps program I suppose

sausage
QLD, 4796 posts
24 Apr 2015 10:57AM
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seanhogan said..
with the phone connected to the computer via usb you should see the file

prob something like : computer/phone/sdcard/gpslogit/your file

then it's just as usual with a gps program I suppose



Thanks Sean - it was just a phone to computer USB debugging issue. Got it now. Opened in realspeed and I got a 2sec PB driving to work . Will run it against the GT-31 and update results. Accuracy looks pretty good from just the tracks too.

boardsurfr
WA, 790 posts
24 Apr 2015 9:25AM
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Tried it today with a $70 (US) RCA M1 phone. Results are quite encouraging:
GT-31 Logit
2s 27.49 27.22
5x10 25.36 25.31
1h 15.83 15.56
nm 19.61 19.30
alpha 20.51 19.74
km 58.30 56.66
km>10mph 54.69 53.59

Most numbers are very close, only alpha was a bit lower (but still within the +- range given by GPSResults). Visual inspection of the tracks and doppler speed graphs shows they are very close to each other. I'm planning to do some more comparisons with multiple GPS units, but on first glance, phone GPS accuracy seem to have improved quite a bit over the past 4 years. The app is pretty cool, too, although I had a hard time reading anything until I took the phone out of the bags.

tonyd
QLD, 382 posts
24 Apr 2015 11:39AM
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Had a play around with it on my phone while suping, seems good enough. Anyone get the onscreen alpha to work.

sausage
QLD, 4796 posts
24 Apr 2015 12:51PM
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tonyd said..
Had a play around with it on my phone while suping, seems good enough. Anyone get the onscreen alpha to work.


Tony,
The way the forecast is up here I might have to take up SUPping . Didn't notice the onscreen Alpha either but Realspeed gave me a sweet one going round a roundabout!

sailquik
VIC, 4639 posts
24 Apr 2015 2:56PM
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GPS-Logit Trial V1.3 is now up here: gps-speed.com/download_e.html

Apparently there are some issues with some phones versions that this version is attempting to address.

John340
QLD, 1934 posts
24 Apr 2015 4:59PM
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boardsurfr said..
Tried it today with a $70 (US) RCA M1 phone. Results are quite encouraging:
GT-31 Logit2s 27.49 27.225x10 25.36 25.311h 15.83 15.56nm 19.61 19.30
alpha 20.51 19.74km 58.30 56.66km>10mph 54.69 53.59
Most numbers are very close, only alpha was a bit lower (but still within the +- range given by GPSResults). Visual inspection of the tracks and doppler speed graphs shows they are very close to each other. I'm planning to do some more comparisons with multiple GPS units, but on first glance, phone GPS accuracy seem to have improved quite a bit over the past 4 years. The app is pretty cool, too, although I had a hard time reading anything until I took the phone out of the bags.



Its a pity that the Logit result is always less than GT-31

decrepit
WA, 9171 posts
24 Apr 2015 6:32PM
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John340 said..
>>>>>>>

Its a pity that the Logit result is always less than GT-31


Not necessarily, If I can figure a way to read mine while sailing, I'd use it to check how I'm going against a target, and a GT31 for my results. At least with a conservative read out, you can be fairly sure the target has been reached.
If I didn't have a target to aim for I'd probably not bother taking the phone out.

boardsurfr
WA, 790 posts
24 Apr 2015 10:13PM
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John340 said..

Its a pity that the Logit result is always less than GT-31


That's one session on one phone. I would not draw general conclusions from that, except that more testing is needed. If use only data from the first half of the session, the 2 sec and 5x10 speeds are actually lower for the GT-31 data. Long distance numbers are still higher, but I think I have seen this before with other GPS units, and that the GT-31 might be a bit "optimistic" there.

Different phones have different GPS chips, so may give different results. The phone tracked 1-2 more satellites than the GT-31, so it is possible that the phone was more accurate.

boardsurfr
WA, 790 posts
24 Apr 2015 10:26PM
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I have sent some feedback to the author of GPSLogit, Manfred Fuchs (also the author of GPSResults). He appreciated the feedback, and wrote back:


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Manfred Fuchs said..
I'm just implementing an upload to GP3S. I could also implement an upload to GPSTC, however, I would need examples of the format they expect there.




Maybe someone could get back to him on that? His email is info (at) gps-speed (dot) com.

berowne
NSW, 261 posts
25 Apr 2015 6:44PM
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New Alternative to GT-31...Samsung Galaxy Young GT-S6310T 3G Wifi GPS 1GHz Android Smartphone


Last weekend I used a cheap android phone to record my tracks, since my GT-31 drowned.

I downloaded the app; "Ultra GPS Logger" for $7. It has a host of useful features such as logging per second (not the default!) and outputs to NMEA and GPX.

To view the accuracy, I've run the track through GPS Results software package. gps-speed.com/download_e.html. Not GPS-Speed.com also have the package mentioned above, but it failed to install due to old android version installed.

Below is a screen shot of the results. Using the Doppler settings the max speed is shown as 38.4 kts, with 0.5m/s^2 acceleration, so quite reasonable. Without Doppler the peak speed is 39kts with 1.1m/s^2 accel. The 'HDoP' reading of 1 indicates the horizontal (H) position reading is 'excellent'.
The KA72.com website interpereted the same track with a peak speed of 37.9

gpsteamchallenge.com.au/sailor_session/show?date=2015-04-19&team=5
www.ka72.com/TrackRecalc.aspx?fid=115295


DOP Value Rating Description
< 1 Ideal Highest possible confidence level to be used for applications demanding the highest possible precision at all times.
1-2 Excellent At this confidence level, positional measurements are considered accurate enough to meet all but the most sensitive applications.
en.wikipedia.org/wiki/Dilution_of_precision_%28GPS%29

So, considering the cheapy Samsung "GT-S6310T" from Telstra running Android 4.1.2 is just $80, is about as water proof as the Canmore, provides SDOP error levels and satellite count (10 in my example), it appears as a worthwhile contender... unless I'm missing something.









powersloshin
NSW, 1009 posts
25 Apr 2015 7:05PM
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KA 72 speed of 37.9 is 2 second peak, your 38.4 on GPS result is absolute maximum, you need to click on the 2 sec radio button to get the 2 sec peak in gpsresults. I think the issue is not how the files look after you process them with different software, but if the device records the data file with the same accuracy as gt31. The easiest test would be to do a few runs with both devices and compare the output.

berowne
NSW, 261 posts
25 Apr 2015 7:09PM
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For comparison, my previous GT-31 result, which shows lower accuracy! (IN HDOP terms).
Not this is a different day. I don't have a GT31 to compare with anymore!

gpsteamchallenge.com.au/sailor_session/show?date=2015-03-15&team=5
Only 7 sats, and a less accurate HDoP reading of 2.4.



berowne
NSW, 261 posts
25 Apr 2015 7:17PM
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Just noticed the bottom left quarter, speed results includes mSDoP and min/max details that are not available with the cheapy GPS!
Does anyone know if the Canmore 102+ firmware been updated to include SDoP?

seanhogan
3033 posts
25 Apr 2015 5:25PM
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tried it today in the car next to my two canmores




Only issue I had/have is to find the bloody file !! Nowhere to be seen, so the stats you see are from the screen.

Also had an Xperia Active, with GPS speed talker (does doppler)
The Sony is closer in results to the canmores than the asus with logit, but definitely doesn't have all the nice info displayed like the new software.

So all in all quite good app but I still wonder about the cost:

Use a canmore gps in a waterproof bag : approx 100 $
Use an android phone with jelly bean 4.2.2 in a waterproof bag : >+ than 100$ (not much more though if you get a cheapo one with the new android)

You can find cheap phones that'll do the job, but will you use it as your everyday phone ?
If you use your "good" phone, in case of submersion you will still risk drowning an expensive device compared to just wetting a "water resistant" 80$ gps...(that will still work after a trip in the rice bag)

In favor of the logit app, you have access to your results on the beach. I personally don't care as I only check my results once home.

My 2 cents

decrepit
WA, 9171 posts
25 Apr 2015 7:46PM
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>>>>

Only issue I had/have is to find the bloody file !! Nowhere to be seen, so the stats you see are from the screen.

>>>>>


OK so I assume your screen 10s stats are the 5x and the canmores are the highest 10s?

On my phone the file is in the main phone memory (not the SD card) in the gpslogit file.
So with the phone connected to computer via USB, and the phone set to MTP communication, (not Photos), I can browse through the phones files.

boardsurfr
WA, 790 posts
25 Apr 2015 10:02PM
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seanhogan said..
tried it today in the car next to my two canmores




Only issue I had/have is to find the bloody file !! Nowhere to be seen, so the stats you see are from the screen.



You must have copied some of the numbers wrong, considering 250 is higher than 2 secs for the asus.

GPSLogIt will show speeds even if you do not press "Start recording". After you press "Start Recording", it will create a file in the "GPSLogIt" folder. To get my phone to mount as an external USB drive on my Mac, I have to reboot the phone first.

If you use GPSLogit for windsurfing, keep in mind that the current version will keep updating speeds on the display even after you stop recording. So if you leave the app running for your drive home, you may see your top driving speed when you get home. That affects just the display, not the file, and should be fixed in future versions.

boardsurfr
WA, 790 posts
26 Apr 2015 2:02AM
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I did some more testing, comparing my Android phone with GPSLogIt to 5 other GPS units (2 x GT31, 2 x Canmore GP102, 1 x Flysight).





5x10 is very close, but nautical mile and alpha are a bit lower. Looking at the tracks, the phone tends to read low sometimes in curves and when accelerating. Differences are less than 0.6 knots, though, and typically 0.1-0.3 knots. More details at boardsurfr.blogspot.com/2015/04/gps-speedsurfing-with-your-phone.html

Boombuster
QLD, 499 posts
26 Apr 2015 9:13AM
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I tried downloading the app on a moto g xt1033 this mob meets all the requirements but it just won't open the file I allowed other apps in security settings I even went over to a local tech wiz but the phone just says can't open file.
We tried it on his mobile & it worked.
I give up

seanhogan
3033 posts
26 Apr 2015 8:34AM
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boardsurfr said..


You must have copied some of the numbers wrong, considering 250 is higher than 2 secs for the asus.





My first thought too, but I doubled checked and that's what was displayed.

Thanks for the advice, after reboot the files can be found

Just wish it would work on older androids as my sony Active is a real waterproof and I take it with me when I sail (with a prepaid sim to call the gendarmerie if lost at sea...)

Other thing I noticed when try to upload to Gps speed results is that it won't accept the files from my phone, I need to transfer them to the PC first.

boardsurfr
WA, 790 posts
26 Apr 2015 9:38AM
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Glynn Merrit said..
I tried downloading the app on a moto g xt1033 this mob meets all the requirements but it just won't open the file I allowed other apps in security settings I even went over to a local tech wiz but the phone just says can't open file.
We tried it on his mobile & it worked.
I give up


If you just click on the file in the browser, Android will think it's a text file, and show it as a ".txt" file in the file browser on the phone (but it shows up with the correct name & extension on the Mac when I connect the phone!). There are two ways around this:
1. Press on the link, and keep pressing until the popup menu opens. Then choose "Save link".
2. Rename the file manually from ".txt" to ".apk
Both of these methods work on my phone (after, of course, changing the security settings).


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seanhogan said..

Just wish it would work on older androids as my sony Active is a real waterproof and I take it with me when I sail (with a prepaid sim to call the gendarmerie if lost at sea...)



A cool thing in the US is that you don't even need a SIM card to call emergency services. Apparently, that's a federal requirement in the US. I have not tried it, but when I switch the phone on, it says "No SIM card - emergency calls only".



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seanhogan said..

Other thing I noticed when try to upload to Gps speed results is that it won't accept the files from my phone, I need to transfer them to the PC first.



Manfred, the author of GPSLogIt, has offered to add a direct upload to GPSTC. I have sent him the link to the "Integration" page from the GPSTC web site. However, the information on the page is not quite complete - specifically, how to deal with login info is not discussed. It would be good if someone with the necessary technical knowledge would get in touch with Manfred. Maybe sailquik could hook them up to discuss this?


seanhogan
3033 posts
26 Apr 2015 9:53AM
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boardsurfr said..

A cool thing in the US is that you don't even need a SIM card to call emergency services. Apparently, that's a federal requirement in the US. I have not tried it, but when I switch the phone on, it says "No SIM card - emergency calls only".


Same on my phone, but doesn't work without a sim card here. Too many prank calls, you don't need credit, just the sim so they can trace a number in case....

boardsurfr
WA, 790 posts
26 Apr 2015 10:30AM
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Played around a bit more with the file transfer Android 4.4.2 -> OS X 10.9.5. Using USB required rebooting the phone a lot, and even then did not always work. Bluetooth seems to work better, once you're through the initial setup (which I find a bit confusing, but I almost never use Bluetooth). Anyway, I found helpful instructions on how to do this at www.howtogeek.com/208365/how-to-use-bluetooth-file-transfer-between-os-x-and-android-5.0-devices/

Instructions are for Android 5, but it seems to work more or less the same on Android 4.4.2.

sausage
QLD, 4796 posts
26 Apr 2015 2:52PM
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Driving test yesterday heading up the beach (I didn't post the different Nm's because I turned the app off about 3km before the GT-31 and don't have programme on home computer to delete tracks off GT-31 file. No hour or alpha recorded for either file)
GT-31 - Logit
2sec ........51.56 - 51.75
5x10 ave 40.61 - 40.55
1.(10sec) 51.16 - 51.03
2.(10sec) 47.27 - 47.43
3.(10 sec) 35.43 - 35.04
4.(10 sec) 34.91 - 34.89
5.(10 sec) 34.26 - 34.36
100m peak 51.35 - 51.33

Very surprised with the accuracy of teh Logit app.

If only this was done windsurfing

boardsurfr
WA, 790 posts
26 Apr 2015 11:11PM
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sausage said..

Very surprised with the accuracy of teh Logit app.


The app mostly records what the phone GPS puts out (well, it does calculate the numbers, but that's an issue Manfred has solved in GPSResults years ago). The interesting thing is if there are differences in accuracy for different phones. Did you use the HTC One XL v4.2.2?



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Forums > Windsurfing   Gps and Speed talk


"Alternative to the GT-31" started by Tony Wills