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Okay, so I just tested my iPad 3+4G and my iPad 2+3G (U.S. models).

I was incorrect about cellular data mode. GPS functions properly with both WiFi and Cellular Data turned off. It is Airplane Mode that turns off the GPS, not cellular data off. It's the same reason (GPS receiver is built into the cellular chipset) but turning off cellular data does not shut off the cellular chipset (on phones, you can still make calls on an iPhone with cellular data off). It is Airplane Mode that actually turns off the cellular chipset.

I haven't tested the iPad 1 because the model I have on hand is WiFi only.

Matt

mastreb wrote:Okay, so I just tested my iPad 3+4G and my iPad 2+3G (U.S. models).

I was incorrect about cellular data mode. GPS functions properly with both WiFi and Cellular Data turned off. It is Airplane Mode that turns off the GPS, not cellular data off. It's the same reason (GPS receiver is built into the cellular chipset) but turning off cellular data does not shut off the cellular chipset (on phones, you can still make calls on an iPhone with cellular data off). It is Airplane Mode that actually turns off the cellular chipset.
Matt

Which proves the fact that GPS is indeed built-in! Matt, I can't understand how I could make a call with cellular data turned off? Would it also be that Airplane mode (ok, I am a bit removed with my Apple background - these days.) might heterodyne, or something similar, with the planes onboard system and affect it?
R.

Crikey wrote:Matt, I can't understand how I could make a call with cellular data turned off? Would it also be that Airplane mode (ok, I am a bit removed with my Apple background - these days.) might heterodyne, or something similar, with the planes onboard system and affect it?
R.

The cellular telephony chipset (GSM or CDMA) usually (but not always) uses a different radio than the high-speed cellular data radio, which is usually UMTS or LTE these days. So turning off cellular data only turns off the "data" radio, and leaves the telephony radio active. This is why you can have both a voice and data call active on GSM networks like AT&T.

Cellular phone calls are digital, but they are encoded in a much lower speed real-time framing protocol (GSM) that has much different bandwidth, performance, and guarantee characteristics than LTE which is optimized for packet data and non-real-time protocols like TCP/IP (Internet Protocol). The lower data rate results in longer "bits" that are more immune to interference. As you increase bandwidth, reliability, distance, and immunity to interference go down, which would result in degradation of voice quality. Non-real-time protocols like email and web don't need these guarantees, so they can go as fast as possible and suffer a few percent packet loss without noticeable degradation of service.

It's likely that cellular telephony will eventually be encapsulated on top of cellular data and separate radio for telephony will be eliminated. Now, keep in mind that this is all done on a single chip, so I'm actually talking about separate radios in a logical sense rather than physically separate devices. Like the fact that you have both an AM and an FM radio in the same set.

The ability to turn off cellular data is there to ensure that a data connection goes over WiFi. This can be important, for example, if you using resources inside a network that cannot be reached from the Internet, such as your home or place of business.

Airplane mode turns off all radios on the phone: WiFi, cellular telephony, cellular data, bluetooth, and GPS. This is not because they have been shown to interfere with anything, but because the FCC and the FAA are extraordinarily risk averse, and because there's no real reason to use them on a plane anyway.

The man!

That's great news, since it eliminates another worry of mine....if you had to have cell turned on to use GPS, my guess is in areas with no signal the radio power would be turned up high to search for stations...killing battery life....

mastreb wrote: Airplane mode turns off all radios on the phone: WiFi, cellular telephony, cellular data, bluetooth, and GPS. This is not because they have been shown to interfere with anything, but because the FCC and the FAA are extraordinarily risk averse, and because there's no real reason to use them on a plane anyway.

I have no technical explanation but I remember my now ancient Nokia 5190 used to shut down my Volkswagen Jetta when it rang if I left it on the dashboard. The lights would literally all dim and the plugs would stop firing momentarily. It was scary. I am glad phone don't have the same power anymore

I regularly use 'airplane mode' when I put the IPad3 to sleep to conserve battery power. Otherwise, all night long the unit is using power. The GPS chip in the Ipad3 uses more power to run than wi-fi or cellular. At 95% power that I have right now, I could use the Internet Wifi for 9 hours, but GPS navigation for only 3:36.

Everything everyone is telling you is a lie!
http://www.youtube.com/watch?v=wlMegqgGORY

Sumner, I just started at the end,I didn't look at the Post because I have a Iphone 4.
I phone 4 has gps, navigation tools. I don't know if Ipad can except a app. (Charts) Cost $12, DragQueen (alarm goes off if dragging) .(without wyfy)
The charts is a full funtion Noaa charts, Navigation tools and gps tracking and a whole lot more.(without wyfy)
Noaa with radar,currents,wind and others,there are also other sites such as Sail flow, Wunder and a few others.(without wyfy)
These are all on the I phone 4, you need to download the Apps but most are free.
I have Wyfy that I can turn on and off but only picks up in areas that has it but I still get internet service in most areas on boat and always on land.
Maybe I am missing something from previous posts.
Dave

Sumner wrote:

Catigale wrote:All

The answer to the post has been placed in the first post by edit, for posterior.

You mean I now have to go back 6 pages to find the answer and exactly whose posterior are we referencing .

Sum

Ormonddude wrote:They triangulate off the cell phone towers so it can only work in cell phone areas - at least thats what I believed until this thread said different.

I know y'all want to believe your cellphone has a dedicated satellite receiving gps but that is not correct. This is the correct answer for 90% of cellphones. They triangulate position from cell tower locations. No dedicated satellite gps.
Exactly what he says above.

My Android devices:Sony Experia X10 and Toshiba Thrive tablet both have GPS that functions out of cell phone range. We used the Navioncs maps throughout the BVI's and well out of range in parts like on the the way to Anegada. The Thrive does not have cell phone capability.

When a cellular device is permitted to operate, in a plane, it will probably connect through a transponder hub, carried by the plane. The tower calculations function from that point forward. A handheld true GPS could find the satellites aboard an aircraft.
Otherwise, explain how my cell-phone runs out of coverage when I'm sailing up north?

I run both my Iphone gps and separate Navigation GPS and both always give me percise location of Lat. and long. positions.
I always use any perdent means to navigate and still to day I also use dead reconing.
All Sailors should do the same and have local charts aboard and no how to use them and Current/ tide charts.
Dave

uanhanlouee wrote:

Ormonddude wrote:They triangulate off the cell phone towers so it can only work in cell phone areas - at least thats what I believed until this thread said different.

I know y'all want to believe your cellphone has a dedicated satellite receiving gps but that is not correct. This is the correct answer for 90% of cellphones. They triangulate position from cell tower locations. No dedicated satellite gps.
Exactly what he says above.

Try using the 129/149 tables of a Sextant in 40 ft. seas for 1200 miles. 400 of those miles were in 40 ft. seas.
Much easier getting a fix back in 1940 in a airplane than in 1982 in a 35 ft. boat with those seas.
How have things advance, If I was just 30 years younger.
Dave

Crikey wrote:When a cellular device is permitted to operate, in a plane, it will probably connect through a transponder hub, carried by the plane. The tower calculations function from that point forward. A handheld true GPS could find the satellites aboard an aircraft.
Otherwise, explain how my cell-phone runs out of coverage when I'm sailing up north?

It has been a while since my last visit so I am late with my 2 cents worth but I did enjoy reading all 7 pages! My bad, you guys, sure can argue! My objective opinion is that Mastreb has the most credible viewpoint and is better at qualifying his statemnents.

fishheadbarandgrill wrote:Gents,

You're presuming that Assisted GPS is not true GPS but some dumbed down version using cellular triangulation. No true. Assisted GPS is a function where cellular tower triangulation is used to decrease the time needed to establish a valid fix (with GPS satellites). As an example, if you have a GPS in your car, you'll notice that it may take several minutes to lock in a location... usually displayed as "searching for satellites". This is not the case with an "assisted GPS" product which will lock in a location very quickly.

I love Wikipedia because it boils things down so that Zoology majors like me can understand...

"Standalone GPS provides first position in approximately 30–40 seconds. A Standalone GPS system needs orbital information of the satellites to calculate the current position. The data rate of the satellite signal is only 50 bit/s, so downloading orbital information like ephemeris and almanac directly from satellites typically takes a long time, and if the satellite signals are lost during the acquisition of this information, it is discarded and the standalone system has to start from scratch. In AGPS, the Network Operator deploys an AGPS server. These AGPS servers download the orbital information from the satellite and store it in the database. An AGPS capable device can connect to these servers and download this information using Mobile Network radio bearers such as GSM, CDMA, WCDMA, LTE or even using other wireless radio bearers such as Wi-Fi. Usually the data rate of these bearers is high, hence downloading orbital information takes less time."

So when I fire up my Navionics map I have instant location information, even with cellular data off BTW. Now, it will take about a minute for Navionics to display a heading and speed over ground. That's because the app is using GPS data (not AGPS) to make the calculation.

Bob
S/V Syzygy

I believe that Bob is spot on here about A-GPS, the Almanac is annual whereas the Ephemeris is bi-weekly, but your chartplotter requires a current dataset to get a quick Time-to-First-Fix. If you leave your chartplotter off for the winter like us in the northern climes it can take 12-15 minutes for your chartplotter to acquire this data upon first power up in spring. My Garmin GPSMAP 76 CS handheld takes this long on first power-up. As long as you use the chartplotter regularly like at least once a week the dataset is updated for you behind the scenes while you have the chartplotter running. It simply updates the current Ephemeris for you after it gets a fix using the previous Ephemeris , so your Time-to-First-Fix is immediate and your update goes on in the background. With regular use your dataset is current. My handheld Garmin has a quick Time-to-First-Fix even when shut off overnight once I have the dataset and with regular use it is always quick, it is only slow when not used for a couple weeks.
With your cellular devices this dataset is requested through the service provider servers and is sent over your cell towers to your device and apps very fast so you get a quick Time-to-First-Fix, with the Assistance of the Ephemeris and Almanac, no tower triangulation required.

I have an iPhone 4s, iPad 3 (WiFi only) and older iPod. I purchased UltiMateGPS by Emprum software(free) from the app store and the hardware dongle that fits the iPad port from Emprum ($99.00) I did not go the Bluetooth route. The app has settings for updating the GPS dongle with current Almanac and Ephemeris through your WiFi or cellular but home WiFi does not use your data plan like cellular does. It will also alert you when the 2 week window expires and also provides you with the start and finish dates of your 2 week window for self monitoring. I update mine every 2 weeks right here at home over WiFi so my dongle is always current. The app also has a feature for displaying the relative satellite positions in concentric circles and bars showing comparative signal strengths and how many are up there, my Garmin has this feature also. Both my Garmin and iPad are quick with T-T-F-F as long as the Ephemeris datasets are current. If I use my iPhone it may likely make a data request to the service provider and incurr data charges or roaming if I am out of range. The cellular versions of iPads can also retrieve the Ephemeris and Almanac either while in WiFi range or more slowly via the satellites but once acquired and stored, it is fast with TTFF.

Mastreb is correct about resident charting apps, Navionics is a good choice so is Jeppessen Plan2Nav by Boeing, they both cover the whole west coast and I quite like the Jeppessen app. The internet based ones are useless out on the water and will incur data charges. I also have NcCharts, eSeaCharts, SailTimer and Charts&Tides U.S. west Coast. The NOAA based charts are limited with use above 49 degrees as they do not cover this are well. But they do have their use with Active Captain data below 49 degrees. I have quite a collection of nautical apps, more than I need but I like them anyway.

I also purchase apps that request permission for “push notifications” and “use current location”, after my yes reply the app finds my iPad very accurately via the WiFi address and my iPad is not cellular and I do not have the dongle attached. Therefore I concur with Mastreb about the WiFi triangulation and also when I go to settings/WiFi all other surrounding WiFi positions are listed, locked perhaps but still listed. I can only surmise that WiFi locations are being used. I can update my dongle Ephemeris at any WiFi hotspots such as marinas or restaurants or on the go via satellite if need be. I do not need cell towers but if it comes down to it I can use my iPhone as a personal “HotSpot” and tether my iPad to the iPhone Hotspot and update it with new data. That is why I bought the WiFi only version because I had data access thru my phone.

PS has anyone heard of Photon Browser for using flash on Apple devices, I just read something about it but have not tried it, apparently one can use Active Captain on the iPad with it. I’ll have to scope it out.
PS,PS Check out the Griffin "Survivor" cover for your iPad, it is rainforest and sandstorm proof, military tested and cost me $60.00. can't use the dongle with it though because the port is blocked.

Here are a couple You tube articles on Chartplotter technology
http://youtu.be/zUZceLjMQmw

http://youtu.be/bmtuk7Kyq4A
Good to hear evryone is alive, well and battling