Tablets as GPS's: two Ipad's vs Playbook - Page 2 - Canadian TV, Computing and Home Theatre Forums

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post #16 of 28 (permalink) Old 2013-03-19, 11:10 PM
 
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A small GPS/Navigation rant

I want to raise something that has been kind of gnawing at me while I have been reading this thread. I think it is appropriate to post it here.

An important distinction is missing as we start to call every device that helps us find a location or a direction a "GPS". GPS is a system that tells us where we are located on the planet - it is not a vehicle navigation system, a back country trail map, a chart plotter or a satellite aimer. Those services are layered on top of the information we get by using the Global Positioning System.

All handheld navigation systems, marine chart plotters, car navigation systems or anything else using a location derived from the GPS will have errors. The system itself is never going to give you a 100% accurate location. On top of that, the data we layer on top of the GPS was gathered by humans, plotted by humans, coded by humans.

Cartography is an art, not a science. A very large amount of the data in our navigation systems is still based on hand surveying from many, many, many years ago. Do you know for sure that when you really, really need it you are getting an accurate picture of what is around you? Or is it your "lucky" day and all of the errors are compounded at exactly the wrong time? Google search for "Albert and Rita Chretien" and see what you come up with.

My Garmin Nuvi 1450 that I update every time the updater tells me there is new data available still doesn't know that a stretch of Highway 792 in Alberta I drive constantly is paved. It's probably been paved for 20 or more years. The Nuvi knows where I am on the planet but it doesn't know the features around me because a human has not given it the right information.

I still remember vividly coming into Malibu Rapids in Princess Louisa Inlet when the chart plotter was 100% sure we were 3 miles inland. Which would place us on top of a mile high mountain. How I'd get a 34 foot sailboat up there I have no idea, we had a hard enough time getting the boat in against the last of the ebb.

If you are driving on the highway or hiking in the mountains, have a reasonably current paper map with you. If you are out on a boat, have real charts. Do not depend on a GPS based navigation system as your sole method of navigation.
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post #17 of 28 (permalink) Old 2013-03-20, 08:27 PM
 
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Envirogeek, I totally agree with your every word. However like I said earlier, I own a Nuvi 660 that, when connected to a rooftop puck antenna will display accuracy of 2-3 meters in southern Quebec. By the way I think the 6xx models were one of the last to display signal strenght on ALL satellites that it is using.. Can I trust this value (regardless of map points)? If so, my device (whenever it works) has pretty good sensitivity wouldn't you say. Now if we go back to the second post, the article referenced by the supplied URL states accuracy of about 13 to 20 meters for idevices. Now that's poor.

And about the satellite aiming app I was referring to earlier, it is indeed the DishPointer app and no I would not think of plucking the iphone against a mast pipe to tell where it's at. I was just using the app in broad open terrain somewhere in western Maine to assess some bird location low on the horizon (@129) to tell whether I was below tree line and that thing was totally useless given that I had no cell coverage there. But like I said, I won't give up and will give it a try whenever I get a chance to go... out there with cartography apps.

Could anyone point to a map program that "supposidly" works so I can download it. I'm watching for NavteQ North America to go on (substantial) sale but that hasn't happened yet. I hear the app drops big in price once or twice a year from something like 59$ to 25$.

Going nowhere @ 220 ft
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post #18 of 28 (permalink) Old 2013-03-20, 11:08 PM Thread Starter
 
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ChannelMaster, the link in the 5th post evaluates app's for various idevices. There are a number of Garmin hiking GPS's vs Iphone 4s or 5 comparisons - tracks are indistinguishable between devices even in remote mountainous regions, so the only real issue between these devices is battery autonomy. I haven't seen enough comparisons with the Ipad to determine if the GPS/GLONASS implementation is as good as on the Iphone 4S/5.

As envirogeek has pointed out, choosing a map set depends on what you intend to do with it: driving, cycling, hiking or boating/sailing....!
For cycling and hiking, the OpenStreetMaps seem to be the most up to date (at least for Germany and the Netherlands), although this varies among countries. For driving, the Navteq products are good, but not free. Again, you have to experiment with different products, to see which maps/apps best suit your needs.

BTW, all Nuvi's since the 2xx series display satellite strength by channel, if you press and hold the satellite strength icon for 5 seconds in the top left hand cornier of the Nuvis.
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post #19 of 28 (permalink) Old 2013-03-20, 11:51 PM
 
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Ok. So you've got to keep your finger on it for a while? Good to know. Now I'll like my ipad alot if it can actually do drcent GPS. Excuse me for not having read the article... far enough. And thanks for putting up eith my ignorance... and I do mean it.

Going nowhere @ 220 ft
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post #20 of 28 (permalink) Old 2013-03-21, 03:11 AM
 
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I look at 13 to 20 metres error in a non dedicated device considering the size of the globe to be amazing. Mark a spot on the ground, then stand on that same spot on different days with a handheld device and I'd be surprised if you get the same value.

In the quick and dirty example I gave before using my Theodolite Pro image and Google Earth, those two values are 13 metres apart. The values I used also have different sig figs, and I was pulling the Google Earth location from imagery that is somewhere between 15 and 30 metres resolution.

I trust the developer of an app who has worked intimately with the technology when he says in his online user guide updated Feb. 7th, "Under optimal conditions (clear line of sight to the sky with signals from at least four satellites), the newest iOS devices generally have a position accuracy of 10-15 feet and an altitude accuracy of 15-25 feet."

http://hunter.pairsite.com/mobile/th...lp/index3.html

If the snow ever stops falling at the cabin I think I will stand out in the middle of the yard and do a little analysis with my iDevices and my Garmin's to compare the results amongst them.
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post #21 of 28 (permalink) Old 2013-03-21, 06:38 AM
 
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Quote:
Originally Posted by envirogeek View Post
have a reasonably current paper map with you. If you are out on a boat, have real charts. Do not depend on a GPS based navigation system as your sole method of navigation.
I have had a gps from shortly after they first hit the market. I always have a compass in my pocket when out in the bush or in my boat. Batteries die, drop it and crack the screen, just dies completely in mid use like my old lowrance did...
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post #22 of 28 (permalink) Old 2013-03-24, 03:31 AM
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Quote:
Originally Posted by Tanta View Post
On a recent trip with friends, I was able to test the GPS capabilities of three tablets: two Ipads (1) Ipad2+3G with no active cellular phone subscription, and (2) Ipad mini with no 3G. Both were tested with the IOS 6 version of the 'Maps' app.

The playbook's GPS was activated with GPSMaster, and then the Osmand app was used with cached maps of the area. The comparison was carried out on a boat trip in coastal sea waters in the Gulf of Mexico, near Naples, Florida.

For the test, all three devices were cold started while traveling on water, away from potential WIFI sources, but within 3G/4G service areas. The Ipad mini, was able to track the location for about 3 km from the starting point; presumably using its built in compass, accelerometer and cached maps. Then, the location point disappeared.

Both the Ipad2+3g and Playbook were able to track location perfectly, throughout the nearshore/offshore sea journey, but the Playbook's location accuracy was much greater; often under 1.2 meters, while the Ipad's was never better than about 15 meters.

Given that the Playbook, has a built-in GPS chipset that communicates with orbiting satellites, the results for this device were not too surprising.

However, how an IPad2+3G with no active subscription, and 3G set to 'inactive' in settings, accomplishs this is more enigmatic. Can part of the Ipad's '3G, package' communicate directly with satellites, or perhaps triangulate using cell towers in a manner analogous to 911 geolocation?

Note: I am not condoning use of any tablet as a replacement for a dedicated GPS, just interested in their technical capabilities! Also the Ipads will geolocate using A-GPS much more rapidly and inside buildings, something the Playbook cannot do, since it requires open skies to function properly.
Did you try with samsung tablet?
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post #23 of 28 (permalink) Old 2013-03-24, 09:36 AM Thread Starter
 
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No, didn't have one on hand.
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post #24 of 28 (permalink) Old 2013-03-24, 11:12 AM
 
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So you guys are keeping this thread alive? Well just so you know, I gave in and installed Navigon on both ipad 4 and iphone 5. Tried to navigate from my home to Costco and it behaved well (quite well actually) but then again I'm in the city and I suppose Garmin relies on A-GPS when cellular is available. I'm wondering, I just can't tell. Anyway, accuracy was a consistent 16 feet.

Anyone knows how I can "force" true GPS without the proverbial trip to the sticks???

Going nowhere @ 220 ft
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post #25 of 28 (permalink) Old 2013-03-24, 11:29 AM
 
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post #26 of 28 (permalink) Old 2013-03-24, 06:07 PM Thread Starter
 
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To force GPS on an Ipad+3G, just disable WIFI and 3G in settings. Can you do street number address search with Navigon? I'm pretty sure Garmin's do not use A-GPS; this is an Apple only feature.
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post #27 of 28 (permalink) Old 2013-03-25, 09:00 PM
 
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I'll let you know later this week how the ipad 4 LTE handles barebone GPS. And yes Garmin Navigon supports address search and its POIs are a lor more mainstream than on dedicated units. Now more than just florists are acupuncture clinics on main street!

Going nowhere @ 220 ft
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post #28 of 28 (permalink) Old 2013-03-29, 09:06 PM
 
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I am using a Nexus 7 running TomTom as my Mobile SatNav. Great combination. Also used Sygic on the Nexus during my recent trip to Germany. (Free trial) I actually loved the GUI on Sygic more, TomTom can take a few tips. The Nexus is mounted on a Arkon SM517 Windshield Mount. By configuring the Arkon to extend as much as possible the Nexus (in landscape orientation) is almost touching the top of the dashboard. This allows me to have a clear view over the tablet when mounted on the center of the windshield. The Arkon never lets loose, even when hitting some of the potholes on some of the back roads. Great setup.
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