JimFromMD
Well-Known Member
- Aug 9, 2010
- 1,777
- Boat Info
- 2005 300DA, Garmin 740s w/Vision Charts and GMR18HD RADAR
- Engines
- 5.0MPI w/BIIs, Kohler 5E Generator.
All,
Just got this in email from ActiveCaptain. Gives a good description of phones/tablets and GPS capabilities when not in range of towers. I know the topic has been debated and kicked around here several times, so I thought while not 100% specific, it may be helpful for all.
James
>>> Phone and Tablet GPS >>>
Every day of the week we receive some form of the question, "How can I get my position on my phone or tablet when there are no cell towers available?" Apparently there is a rumor circulating that you can't access your position on your a phone or tablet from offshore or when there is poor cell coverage. We'll try to clear up those rumors and provide you with the facts. We'll also give you the information you need when buying a new tablet for your boat. We'll stay away from the nitty-gritty about how GPS works except where it's important in a practical way.
One of the driving forces behind the addition of GPS in phones was an FCC regulation that took effect in 2005 requiring A-GPS in mobile phones. Mobile phone use was sky-rocketing but the E-911 emergency systems weren't able to show precise location information when a call was made from a mobile device. When 911 is dialed on a land-line, the address has already been entered into E-911 and is displayed to the dispatcher. The goal was to have a mobile version of that for mobile phone 911 calls.
There were years of notice about the upcoming regulation and major cellular chip manufacturers started putting GPS technology onto their cellular radio chips early. This meant a mobile phone manufacturer could use a single chip to provide both cellular and GPS radios. Space is critical in mobile phones so it was an obvious chip bundling. With the new GPS capability on cellular chips, many mobile phone manufacturers started making the raw GPS data available to "apps" that were added to the phones.
Today, every mobile phone, especially iPhones and Android phones, has a real GPS inside. That GPS hardware will work in the middle of the ocean with no cellular towers within a thousand miles in any direction. Part of the confusion comes into play with the "A" in the A-GPS hardware. That A is for "assisted."
GPS technology can acquire its initial position much quicker if it knows the approximate location on Earth where the device is located. It's why A-GPS was required for the 2005 regulation - no one wants to dial 911 and then wait 3 minutes while the GPS acquires the first GPS position fix. Instead, through some complex technology that doesn't matter here, having a good starting position greatly speeds up the first fix time so you wait only seconds, perfect for 911. And the starting position technology? That's the mobile phone tower that the mobile phone is connected to - that position is known and is close enough to give the GPS a jump start.
Bottom line - if you have a device today with cellular connectivity (a phone or a cellular tablet), you have a real GPS inside. It'll work incredibly well out on the water without any cellular towers. If you're near a cellular tower, it'll give you a first position fix faster - that's it. The newer devices are even giving us exceptional performance below deck in staterooms at night which provides the perfect anchor alarm. Note that steel boats will have some issues with GPS reception below for obvious reasons.
There's one other confusing part. The new tablets are finding many uses on boats. We've said before that a tablet is the best new electronics device to have onboard. And if you're going to get a tablet, make sure it has a real GPS inside. From above you already know that if the tablet has cellular internet connectivity, it has a GPS built in. But there are many WiFi-only tablets these days including half the iPad models and many Android tablets. For those devices, it is not a given that it'll have real GPS. In fact, no WiFi-only iPad has a built-in GPS because Apple only has the GPS hardware on the cellular chip it uses.
For many Android tablets, the WiFi-only versions do have real GPS support. But you have to look carefully to make sure. Our Nexus N7 WiFi has a real GPS and we selected it because of that capability. You have to check.
If you find a tablet that you like that doesn't have a real GPS in their WiFi version, get the cellular version. Always. The difference in cost will be about $100 which is about the cost of buying an add-on GPS. But the add-on will be another device you'll need to remember, carry along, and if directly attached, will mess up mounting and cases you might want. If you don't need cellular internet connectivity for the tablet because you'll only be using WiFi, don't purchase a cellular plan for the tablet - you don't have to. We have multiple cellular iPads and none of the cellular plans have ever been enabled. We use our iPads over WiFi and through our Verizon MiFi only. But having the cellular iPads means they all have real GPS without anything extra to purchase.
Just got this in email from ActiveCaptain. Gives a good description of phones/tablets and GPS capabilities when not in range of towers. I know the topic has been debated and kicked around here several times, so I thought while not 100% specific, it may be helpful for all.
James
>>> Phone and Tablet GPS >>>
Every day of the week we receive some form of the question, "How can I get my position on my phone or tablet when there are no cell towers available?" Apparently there is a rumor circulating that you can't access your position on your a phone or tablet from offshore or when there is poor cell coverage. We'll try to clear up those rumors and provide you with the facts. We'll also give you the information you need when buying a new tablet for your boat. We'll stay away from the nitty-gritty about how GPS works except where it's important in a practical way.
One of the driving forces behind the addition of GPS in phones was an FCC regulation that took effect in 2005 requiring A-GPS in mobile phones. Mobile phone use was sky-rocketing but the E-911 emergency systems weren't able to show precise location information when a call was made from a mobile device. When 911 is dialed on a land-line, the address has already been entered into E-911 and is displayed to the dispatcher. The goal was to have a mobile version of that for mobile phone 911 calls.
There were years of notice about the upcoming regulation and major cellular chip manufacturers started putting GPS technology onto their cellular radio chips early. This meant a mobile phone manufacturer could use a single chip to provide both cellular and GPS radios. Space is critical in mobile phones so it was an obvious chip bundling. With the new GPS capability on cellular chips, many mobile phone manufacturers started making the raw GPS data available to "apps" that were added to the phones.
Today, every mobile phone, especially iPhones and Android phones, has a real GPS inside. That GPS hardware will work in the middle of the ocean with no cellular towers within a thousand miles in any direction. Part of the confusion comes into play with the "A" in the A-GPS hardware. That A is for "assisted."
GPS technology can acquire its initial position much quicker if it knows the approximate location on Earth where the device is located. It's why A-GPS was required for the 2005 regulation - no one wants to dial 911 and then wait 3 minutes while the GPS acquires the first GPS position fix. Instead, through some complex technology that doesn't matter here, having a good starting position greatly speeds up the first fix time so you wait only seconds, perfect for 911. And the starting position technology? That's the mobile phone tower that the mobile phone is connected to - that position is known and is close enough to give the GPS a jump start.
Bottom line - if you have a device today with cellular connectivity (a phone or a cellular tablet), you have a real GPS inside. It'll work incredibly well out on the water without any cellular towers. If you're near a cellular tower, it'll give you a first position fix faster - that's it. The newer devices are even giving us exceptional performance below deck in staterooms at night which provides the perfect anchor alarm. Note that steel boats will have some issues with GPS reception below for obvious reasons.
There's one other confusing part. The new tablets are finding many uses on boats. We've said before that a tablet is the best new electronics device to have onboard. And if you're going to get a tablet, make sure it has a real GPS inside. From above you already know that if the tablet has cellular internet connectivity, it has a GPS built in. But there are many WiFi-only tablets these days including half the iPad models and many Android tablets. For those devices, it is not a given that it'll have real GPS. In fact, no WiFi-only iPad has a built-in GPS because Apple only has the GPS hardware on the cellular chip it uses.
For many Android tablets, the WiFi-only versions do have real GPS support. But you have to look carefully to make sure. Our Nexus N7 WiFi has a real GPS and we selected it because of that capability. You have to check.
If you find a tablet that you like that doesn't have a real GPS in their WiFi version, get the cellular version. Always. The difference in cost will be about $100 which is about the cost of buying an add-on GPS. But the add-on will be another device you'll need to remember, carry along, and if directly attached, will mess up mounting and cases you might want. If you don't need cellular internet connectivity for the tablet because you'll only be using WiFi, don't purchase a cellular plan for the tablet - you don't have to. We have multiple cellular iPads and none of the cellular plans have ever been enabled. We use our iPads over WiFi and through our Verizon MiFi only. But having the cellular iPads means they all have real GPS without anything extra to purchase.
