Alternative to the GT-31

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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.

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

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

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.

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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!

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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

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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.

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. http://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.

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.

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

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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.

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

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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?

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.

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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?