Friday, December 7, 2012

GARMIN GLO + iPhone - First impressions

Why I was really excited about Garmin's GLO module?

 - Bluetooth pairing with iPod/iPad/iPhone with NO NEED for a jailbreak
- 3 meters accuracy (iPhone comes only to 5 meters)
- 10 location updates per second (iPhone does only 1!)

At home, I paired it with my wifi only iPad, all done within seconds, put the bluetooth module outside and after 30 seconds (totally cold start) GLO had a lock. All cool with wifi only iPad and should be as well with iPods.

But I wanted as well to test with my iPhone (5). One of the video reviews I watched, implied that GARMIN GLO will override the internal GPS and thus I hoped in better quality GPS for my iPhone 5 as well.

iPhone 5 paired with GLO just alright and so I went driving. But location precision reported by the iPhone stayed at 5 meters and by all the behavior one can tell it was still iPhone's GPS that was in use!

So I went to GARMIN's web site, support section to find out that there is no GLO in the list of devices to pick from (sad). I hope they add it soon. Anyway, I sent them the following support request:

I thought GLO will work as well with iPhones by overriding the iPhone's internal GPS. I tried it today with my iPhone 5 and by updates rate and precision I believe this is iPhone's GPS that is still used. Can you confirm GLO really overrides the iPhone's internal GPS module? Or should I apply some settings to let the GLO override the internal iPhone's GPS?

They should reply within 3 business days. Meanwhile I have a warning for those of us who watched the same review video or just implied GLO would override the existing internal iPhone's/iPad GPS to have better GPS accuracy/updates: It might not be overriding! Beware, and I'll update once I have a reply from them.

[Update 7-Dec-2012] I got a reply, very prompt one. +1 to Garmin for that. Though... read for yourself:

> I have looked into this for you and can confirm it will not replace or
> over ride the iPhone's internal GPS it will only boost it.
> I am sorry if this has caused any inconvenience.

Enough? Nooo. So I asked:

May I ask for some technical details or an article for example about
what can be expected from that boost? Does Garmin have any technical
measurements for what we can expect?

Answer from Garmin:

Dear Stanislav Dvoychenko,
Thank you for contacting Garmin Europe.

I am happy to help you with this.
The information is below:

GLO can receive position information from both the GPS and GLONASS
satellite constellations, allowing it to connect to up to 24 more
satellites than devices that rely on GPS alone. This allows GLO to lock
on to satellites approximately 20% faster and remain connected even at
high speed. What?s more, GLO updates its position information at 10x per
second ? that?s up to 10x more often than the GPS receivers in many
mobile devices.

[Update Jun-4 2013] Here used to be a part where I was telling that GARMIN GLO doesn't work with iPhone or cellular iPad and I should tell GARMIN was not helpful at all and never provided any extra information on the issue. BUT since then I got to know guys from Bad-Elf company (producer of Bad-Elf GPS modules) and they solved that issue for me and hopefully You as well if you are reading now.

So, here is to the point. If you are not seeing 10 times faster location and speed updates when GARMIN GLO is paired to your iPhone or cellular iPad, this is just a problem with location services not letting it through as they should. You need to apply this fix: After applying your iPhone/iPad should work as expected and let the better GPS source win - which is GARMIN GLO of course.
Here is a full response from Bad-Elf guys (my big thanks to them for clarifying the issue not only for their modules, but for GARMIN as well):

"iOS *automatically* uses the location services stream that is reporting the best accuracy. That means that for both the Garmin and the Bad Elf, within a minute or so, all location-based apps will get the more accurate feed. No configuration or selection is needed. As for "boosting" the internal GPS performance, I don;t think that's what Garmin means. I think they mean that as soon as the external GPS is more accurate than the internal one, then you get the better feed for free. Same with the Bad Elf. To be fair, I think you should either remove this issue, or give Garmin and Bad Elf a tie on this issue.

I tested with my iPhone 5, and after applying a fix - I can confirm, with GARMIN GLO - it streams 10 location updates per second for sure. Speed readings are very smooth. Don't expect iPhone to show you accuracy of 3 meters, it looks like limitation in location services that even if location samples have 8 decimal digits precision (see M6 comments) it still reports accuracy of 5 meters minimum.

So good news in the end - if you buy GARMIN GLO - you'll have a superior (compared to built-in) GPS instrument not only for your wifi only iPad or iPod, but for cellular iPads and iPhones as well. Cool!I hope this info may help you.

[UPDATE 14-Apr-2013] Here is an excellent hands-on review of GARMIN GLO:

[Update 6-May-2013] If you are in a search for an external module for your iPod or wifi iPad we have an article published here comparing GARMIN GLO and Bad-Elf bluetooth GPS modules. 



  1. I bought a GLO too and just like you, I was expecting more accuracy with my iPhone GPS app, especially in urban environment. It look like that the ability of overriding the internal GPS comes from the application you're using. i.e. : with TomTom North-America : override is OK. if I moved the phone and left the GLO "motionless" nothing happenned. If I move the GLO, coordonates change. With TomTom, refresh rate is still 1Hz. 2nd example : with Garmin pilot application (app provided with the GLO bundle) with my ipad wifi only : very accurate positionning, 10Hz update rate etc. The big deal would be to test this GLO with a more tweakable device like an Andoïd

    1. I had a customer support case today with Dual Bluetooth GPS module. In investigation for him I found out that actually if wifi is left on on his iPod Dual module is not giving any location to iPod. I'm going to try today if I turn off wifi on my iPhone if location is going to be taken from GLO. You mention GLO is working ok in TomTom, any chance you had wifi turned off in the phone? I'll see if this wifi thing makes any difference for GLO.

    2. it's just like if the positionning source were priorized like this for an iOS device : 1) wifi > 2) Internal GPS 3) external GPS

    3. Home already, let me do the experiment and see if I can confirm for GLO with iPhone. Will take 10 minutes only.

    4. With wifi ON or OFF no location from GLO for my iPhone with maps app, my speedo or other "regular" gps apps. With wifi it just stays with 65 meters of accuracy which is typical for wifi and with wifi OFF it goes between 2000 meters and 200 meters, typical again for GSM cells.
      Based on Your observations, I'd say may be if app is using directly NMEA data from the device like TomTom is probably doing in that case, then GLO serves as a source of location data for iPhones. As you say then it is the app capability.
      For my wifi only iPad GLO is serving very well either wifi is ON or OFF, but I see from GPS stats that I'm on ~1Hz with my speedo (which consumes from CoreLocation Apple's framework) and 10 meters of accuracy reported, not 3m.

      Just raw thoughts then and again agree, would be interesting to see some measurements on Android.

  2. And one more thing : Garmin says that GLO is compatible with any NEMEA device : FAKE. My mac and my PC recognize the device as an headset and Google Earth is totally unable to connect to it via bluetooth ...

    1. Another fake in my opinion is saying that bluetooth connection range is 30ft/10meters as from my experience iPad can't pair if GLO is more than 3-4 meters away (no obstacles in the way).

  3. The best thing for Garmin would be to release an iOS application, just like 'Dual' to have infos like current refresh rate, precision, accuracy (not the same thing!) battery level, satellites position in the sky and of course the coordonates ...

  4. Look what the GLO is capable of :

    it's a snapshot of Garmin Pilot app, I had to put the airplane mode ON and then reactivate the bluetooth to connect my iPad to the GLO. It's very accurate but it looks like that an app has to be specifically optimized for external BT GPS receiver if ... Apple SDK allows it ...

    1. This is a nice looking app, they got! Though can't see the accuracy and update frequency there. If they got it as 10Hz and 3 meters then they probably using the Apple's Accessory framework and not CoreLocation. Most of the apps will use CoreLocation framework as they can't rely on NMEA data source to be connected. For my app I use CoreLocation, so seeing ~1Hz on my wifi only iPad with my speedo and 10 meters accuracy. I'll try to see if via Accessory framework I'll see the GLO and will be able to read its values.

  5. you're right, it looks like a tough job to use Apple deep hidden dev features instead of CoreLocation ...

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  7. Hi Stan,

    I did some test on my end with a home made app.

    GLO is able of a 8 decimal numbers (vs. 6 for an iphone 5). Refresh rate is exactly 1 Hz with the iphone. With the GLO, it's not constant. I would say that it's up to 10 Hz. The only unanswered question I have is why is the accuracy still at 10 meters for the GLO vs. 5 meters for the iphone. notice : I used Apple core location for the test!

    1. You were not losing time I see! :). I'll try to measure myself as well with CoreLocation soon and we can compare the results.

  8. Hi again!

    some interesting comments here :-)

    1. Thanks for the link, yeah, looks like it is same for those guys as it is for us :). No one can really tell and GARMIN is keeping silence.

  9. Hi Stan,

    I have some fresh news :

    - The GLO is capable to output 8 decimals precision when using the 2 constants "kCLLocationAccuracyBestForNavigation" and "kCLLocationAccuracyBest" in the Apple SDK

    - I was able to pair it with a mac (had to edit and change the com port to make it work). result : works with everything if setup as a NMEA @ 57000 bps device

    - I did a refresh rate frequency test with MacENC demo : astonishingly faster than my other 1 Hz BT gps unit ...

    this little thing is full of secrets ...

  10. Those are really interesting discoveries you've made! Myself I use kCLLocationAccuracyBest in my apps, adding now GPS tracking, that's a great thing to know that I should not be doing %.6f when writing to a track :), but better %.8f.

    I got two units from Bad-elf I want to test the apps with, first impression is that while their PRO unit is very user-friendly, GLO is really faster with acquiring the lock. Working now on fitting tracking part to iPad, so I can test GLO vs. Bad-Elf accuracy and frequency.

    Cool discoveries on a Mac side! I can see you profile on Blogger, but can't see your blog.. Are you blogging about this? Will be happy to subscribe ...