GPS over WiFi, how does it work?

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GPS over WiFi, how does it work?

I have a iPad wifi and I want to do accurate navigation on it.

Now there are several ways to do that.

I could buy a cable from RedPark and hook on a serial GPS. That one will hook on the location services and all gps. However this mere cable costs $249 ... a tad expensive for my taste.

Then I could get a bluetooth device that talks in a special protocol. A bluetooth GPS device that works on a non jailbroken iPad costs $99 while a bluetooth gps device for lets say android costs $10.

Then there are these MiFi devices like the sprint overdrive. They hook up with the iPad by WiFi and provide an internet connection. The also provide a GPS and hook on to the location services.

My question is: How do these MiFi devices provide the GPS location data to the iPad? Does anyone know if there is a special port or IP involved?

What I want to do is the following: Combine a GPS receiver with an serial to WiFi converter. This already works. However it does not hook up to the location services because I do not know how that works.

Can anyone help me out?

iPad 2 Wi-Fi, iOS 6.0.1

Posted on Jan 19, 2013 1:34 PM

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Answer 1

xnav

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Jan 19, 2013 2:33 PM in response to JelbertH

Sell the WiFi iPad and by a new one with a GPS chip (any WiFi + Cellular model), seriously.

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Answer 2

JelbertH Author

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Jan 20, 2013 3:40 AM in response to xnav

Hi Xnav,

Are you by any chance the one who wrote Xnav navigation program for the iPad? That program is on my wishlist and also part of the reason I'm tinkering around with this project.

When I connect the NMEA gps steam to my iPad I want to include data from other instruments.

Xnav can, i think, include the data anyway by giving the right settings. But I would like to do this through the locationservices so other nav programs can make use of the GPS data too. I probably have to split up the other instruments NMEA data and the GPS NMEA data, but that is a later worry.

Buying an iPad with build in gps. Is the build in GPS accurate enough for proper navigation at sea? No assistance there. The price difference here in Holland between selling,wifi, seccond hand and buying,3G, seccond hand is about €75 ($99).

And besides I would realy like to solve this technical mystery. Then I can put it up my blog and others can also have cheap navigation on their iPad wifi as long as they are not afraid for the soldering iron 😀

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Answer 3

JelbertH Author

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Jan 20, 2013 3:55 AM in response to JelbertH

Ahh it was iNavX and not xnav. So maybe not related at all.😊

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Answer 4

xnav

Level 5

7,089 points

Jan 20, 2013 6:31 AM in response to JelbertH

Are you by any chance the one who wrote Xnav navigation program for the iPad?

No, I'm not. The iPad GPS is as accurate as the iPhone's. Relying on a 'cheap' nav solution at sea could be a mistake.

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Answer 5

JelbertH Author

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Jan 20, 2013 11:57 AM in response to xnav

Yes if it was the only gps onboard. But lets see there is the chart plotter with its own gps, then the secondary chart plotter with its own gps a spare low power gps and in case all else fails and then there is my iPhone 3gs.

I guess i'm covered. And if all of those fail there is an emergency AIS beacon that also has a GPS build in. These chart plotters create a NMEA data output and it would be so sweet if I could also use this on the iPad.

I figured out that the mifi devices probably use the zeroconf network setup and that this would also work for GPS on iPad. This is not tested yet.

The cheapest least reliant GPS in the above list is the iPhone 3gs, using a bad antena and relying on wifi signals and cel tower data to get a quick fix. However there are non of those around at sea.

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Answer 6

Apr 24, 2014 1:46 PM in response to JelbertH

I have just returned from a sail across the Bay of Biscay. Inboard I have full GPS receiver linked via NMEA to the GPS unit, then linked to a laptop running MaXsea (and an external repeater screen). I also have an ipad 4 (with cellular) running Navionics.

I ran both in tandem. At the extreme I was 150 nm from the nearest landmass.

I checked at least once per 2 hours whilst furthest from land, and as coming into our destination I had both working alongside each other as I came to shore.

Basically I saw no deviation between them. It is worth noting that my understanding is that the ipad does not use GPS (the American military system) but the Russian equivalent. The biggest problem was power to the ipad (note I had ruggedised it already).

I would say that for practicality the ipad running navionics was most convenient. Remember to get the detailed charts whilst on a fast network.

Now, I will still have both going in tandem but will prefer to use ipad as primary tool, but I will run the other and still write down my lat and long with SoG, Cog etc regularly. The ipad is a winner.

Also look at April 2014 issue of Yachting Monthly - a good article there (typically I read it on way home from Portugal!)

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