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iPad GPS

K

Kestrel452

macrumors regular
Original poster
Jul 23, 2008
197
256
I have always been really confused on what kind of GPS is inside the iPad. I keep hearing different stories like: only the 3G has a GPS chip, the GPS chips only work when you have access to 3G or cell coverage, the Wi-Fi iPad has a legit GPS chip, etc. I can't figure out what's what. Apple's website says both models have assisted GPS, does that mean they dont have an independent GPS chip that can provide navigation when away from 3G or cell coverage???

I am mainly look at the iPad for aviation uses. I would love to get a WiFi iPad as an aviation GPS. What would be even better is if the iPad could use an external bluetooth WAAS enabled GPS receiver, but I hear Apple programmed the iPad so that it can only transmit audio over bluetooth.

Can someone clarify these things?

Also, when is the iPad expected to be updated? Thanks!

EDIT: What is this Skyhook Wireless thing that Apple has cooked up with the WiFi iPad?
 
The iPad 3G has A-GPS and compass in it and always works unless the iPad is in Airplane mode or in an area where GPS/Cellular reception is poor or nonexistent. The WiFi one only has a compass in it. iPad update - Early to mid Spring. Skyhook is using local WiFi names and IP addresses to locate your location. It isn't always accurate, but it works well enough for Jobs to include. Use Google for more information on how Skyhook and it's relevant technology work.
 
So no GPS at all in the WiFi and no legitimate GPS in the 3G??? Why won't Apple just put SiRF GPS chips or something in these things????
 
As far as I know the WiFi has no GPS. A-GPS is real GPS, it just uses cell tower triangulation to find your general location (hence assisted), then it uses real GPS to find your exact location.
 
I'm fairly convinced otherwise, and do not feel like this needs to be addressed again. Seeing that there are a bujillion threads on this. But I am pretty sure the iPads A-GPS is a regular GPS chip, and has the A (assisted) as an extra. If my Garmin GPS was assisted it would be a better GPS. Not worse.

How is it worse because it uses towers also? It has a FULLY functional GPS chip inside of it. If there are no towers around, it just works like a regular GPS
 
The one thing you should know though, is that the iPad uses data to pull up maps for the GPS to show you where you are. If you will not have a data plan, or will be out of service a lot it is best to buy a Navigation application from the app store that includes maps that will stay on your iPad locally
 
elmateo487 said:
The one thing you should know though, is that the iPad uses data to pull up maps for the GPS to show you where you are. If you will not have a data plan, or will be out of service a lot it is best to buy a Navigation application from the app store that includes maps that will stay on your iPad locally
Click to expand...

Unless you cache the maps in the Maps app when you have data, then the little blue dot follows you on your cached maps.
 
elmateo487 said:
The one thing you should know though, is that the iPad uses data to pull up maps for the GPS to show you where you are. If you will not have a data plan, or will be out of service a lot it is best to buy a Navigation application from the app store that includes maps that will stay on your iPad locally
Click to expand...

I would have to buy that anyways, my main use as far as navigation would go is aviation based.
 
Aviation Software

Myself and two other hot air balloon pilots all use MotionX GPS on iPad for a flight "log". It gives us the track flown, our takeoff and landing spots, etc, and the elevation profile seems to be *fairly* accurate.

I still use a Garmin 60csx in the balloon for the most accurate elevation and rate of ascent descent. It's used as a redundant system for my Ball flight instruments in the balloon.

We all use MotionX GPS on iPad as a convenient way to track our flights and share takeoff/landing spots, as well as time, distance, and speed to add to our paper flight logs.

I don't know for sure on GPS chip details, but all three of us have 3G iPads w/data plans running when we fly. Our altitude is much lower than the typical fixed-wing VFR pilot though -- we rarely have the need to go over 5000' AGL.
 
To the OP,

You may want to go to your local book store and see if you can get the latest issues of aviation magazines, Plane & Pilot etc. They have had several recent articles in them on using iPads for Navigation and list the apps for doing it.
 
The 3G has a regular gps that works without cell coverage. I will try to post a picture later with it in use while flying. I have been able to get a gps signal in a Cessna, but so far have had no luck in airliners. I use motionx gps HD, with the intended route saved. It works great, especially when compared to the limited use and highcost of the Aera.
 
I have an iPad 3G with GPS and use it for flying. I have Foreflight HD and Skycharts Pro and both work great in the plane. They provide moving map functionality and a lot more flexibility than aviation-only devices. AirNav Pro and Beacon are other apps I intend to try, though the latter gets expensive when you subscribe to its maps.

I have an AvMAP aviation GPS too. It has better visibility outside the cockpit, but nowhere near the flexibility and low price of database updates that the iPad provides. I like having all my sectionals in electronic form and updated for free as soon as new ones are released. I also have terminal procedures for IFR approaches.

Only the 3G model of the iPad has a GPS chip inside. The A in AGPS means that it can use cell tower triangulation to obtain its first fix faster. However it is not required to connect to the cell towers to use GPS positioning. It is just an extra advantage. I bought my iPad 3G more for the GPS than for the 3G functions. It was about $100+ extra for the function, but well worth it for navigation applications. I did turn on the 3G to try it out and now I wouldn't want to be without it. Battery life is also pretty good compared to other portable GPS units.

The iPad is a great backup to all the instruments in the plane. The only minuses for me are that the screen is too reflective and can produce glare under certain conditions, and that it does occasionally lose satellite lock for brief periods. You could fix the glare issue with a matte screen protector.
 
The A in AGPS stands for assisted, but this does not mean that it is not "real" GPS - to the contrary, the GPS in the iPad is as good as the US Military will allow (specifically the Air Force as they are, I believe, in charge of the whole GPS thing).

The Assisted refers to the fact that the GPS acquisition is enhanced through the use of cell tower (and Skyhook style WiFi signal) information to triangulate one's position. This has two advantages; 1) this gives faster initial position information, even if not as accurate, and 2) this still works even when the sky is obstructed by objects and structures (e.g. tall buildings or when inside) which is really handy when in a modern city..
 
There is a lot of misinformation about A-GPS and unfortunately this thread also contains repititions of some of them. A-GPS has nothing to do with cell tower triangulation or skyhook: A-GPS uses a location server provided by the cellular network company to provide a faster time to first fix. It does this through a variety of means including providing satellite locations and accurate time. If there is no network coverage, the gps receiver works as a standard one, as it does once it is locked on to the satellites. A-GPS as implemented in most modern devices (including Apple's) is a superset, not a subset of standard gps behaviour. Some early implementations required a connection to the location server to work at all times, but that's not the case with the iPhone and iPad
 
Why is there still so much confusion about this?

The 3g iPad has a fully legit GPS chip. It uses the Doppler signals from the GPS satellites to provide map co-coordinate of your location. Mine right now is aprox : 39° 2′ 0″ N, 125° 45′ 0″ E

Now, as the iPad has no in-built map to look this up, rather than just giving you the values, it uses the internet to look up the location in Google maps and serves you a map. Or you can buy an App that saves maps onto the iPad, doing away the need for 3g/wifi connection.

The assisted part is that, becasue getting the location from the satellites takes a little time, you can use the cell towers and the IP address to provide a quicker aproximate location while the GPS is working.

(Note how first you get the big blue circle from the assisted, then the little blue dot a bit later when the true GPS location is made.)
 
emuyshondt said:
I have an iPad 3G with GPS and use it for flying. I have Foreflight HD and Skycharts Pro and both work great in the plane. They provide moving map functionality and a lot more flexibility than aviation-only devices. AirNav Pro and Beacon are other apps I intend to try, though the latter gets expensive when you subscribe to its maps.

I have an AvMAP aviation GPS too. It has better visibility outside the cockpit, but nowhere near the flexibility and low price of database updates that the iPad provides. I like having all my sectionals in electronic form and updated for free as soon as new ones are released. I also have terminal procedures for IFR approaches.

Only the 3G model of the iPad has a GPS chip inside. The A in AGPS means that it can use cell tower triangulation to obtain its first fix faster. However it is not required to connect to the cell towers to use GPS positioning. It is just an extra advantage. I bought my iPad 3G more for the GPS than for the 3G functions. It was about $100+ extra for the function, but well worth it for navigation applications. I did turn on the 3G to try it out and now I wouldn't want to be without it. Battery life is also pretty good compared to other portable GPS units.

The iPad is a great backup to all the instruments in the plane. The only minuses for me are that the screen is too reflective and can produce glare under certain conditions, and that it does occasionally lose satellite lock for brief periods. You could fix the glare issue with a matte screen protector.
Click to expand...

Interesting, I was wondering which apps to get, so thanks for the recommendations.

I was planning on jailbreaking it to allow the use of a bluetooth connected WAAS enabled GPS receiver. Cydia sells the necessary software to do this, and apparently it's a very simple process to get it fired up. I'm surprised and yet at the same time unsurprised that Apple didn't program the iPad to stream things other than audio through its bluetooth. You would think they'd want as much expandability out of it as possible.
 
Here's a site that lists aviation-related apps for the iPhone and iPad.

I also like Aeroweather for looking up aviation weather at my airports of interest. Nexrad weather and the Weather Channel are also useful. Sometimes they even work up in the air when you are not too high and can connect to the cell network.

I like that once I buy an application I can use it both on my iPad and my iPhone. The phone is not nearly as nice for moving map applications, but it is good as a backup to the iPad. I also have terrestrial navigation apps so I can look up roadways and mark locations where I might want to return to with a car.

I haven't really had the need for WAAS and I don't think I'll be shooting approaches with only my iPad when the minima are such that I'd need WAAS. However it is nice that such an option exists. An external receiver may also be able to keep lock better than the iPad receiver and you can place it somewhere in the cockpit with a better view of the sky.

Overall, I would go with an iPad with aviation applications over a dedicated portable aviation GPS. I will probably sell my AvMap unit.
 
Ciclismo said:
The Assisted refers to the fact that the GPS acquisition is enhanced through the use of cell tower (and Skyhook style WiFi signal) information to triangulate one's position.
Click to expand...
False. That's simply using a separate locating method first.
emuyshondt said:
The A in AGPS means that it can use cell tower triangulation to obtain its first fix faster.
Click to expand...
Ditto.
wackymacky said:
The assisted part is that, becasue getting the location from the satellites takes a little time, you can use the cell towers and the IP address to provide a quicker aproximate location while the GPS is working.
Click to expand...
Ditto.
Phil A. said:
A-GPS has nothing to do with cell tower triangulation or skyhook: A-GPS uses a location server provided by the cellular network company to provide a faster time to first fix.
Click to expand...

True. AGPS in this case is getting satellite info from an internet based assistance server.

AGPS always uses GPS satellites. The other two locating methods are separate and don't use GPS satellites. Putting AGPS, Cell Id and WiFi together forms a "hybrid" locating system.
 
Ciclismo said:
the GPS in the iPad is as good as the US Military will allow (specifically the Air Force as they are, I believe, in charge of the whole GPS thing).
Click to expand...

Though the military retains the capability to reinstate it in time of war, the policy of applying selective availability to gps was ended in 2000 by President Clinton. Civilian access to GPS is just as accurate as military access right now.

However, individual performance varies based on the sensitivity of the antenna, visibility of satellites, presence of EMI and obstructions and the number of channels received by the equipment.

Because of those issues above, the iPad gps works pretty good, but will never compete in terms of accuracy with a more robust system with a better antenna and receiver.
 
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