# What US atlas program should my friend install on his iPhone (to use with my old GPS receiver)? **URL:** \ **Category:** In My Humble Opinion\ **Created:** [December 4, 2012, 1:15am UTC](https://boards.straightdope.com/t/what-us-atlas-program-should-my-friend-install-on-his-iphone-to-use-with-my-old-gps-receiver/642920 "2012-12-04T01:15:01Z")\ **Posts on this page:** 4\ **Page:** 1
**Author:** ![stuyguy](https://avatars.discourse-cdn.com/v4/letter/s/ec9cab/32.png) [@stuyguy](https://boards.straightdope.com/u/stuyguy)\ **Post date:** [December 4, 2012, 1:15am UTC](https://boards.straightdope.com/t/what-us-atlas-program-should-my-friend-install-on-his-iphone-to-use-with-my-old-gps-receiver/642920/1 "2012-12-04T01:15:01Z")
My friend and I are taking a camping trip to the lower Appalachian Mountains (parts of NC, SC, GA & TN). He has a new iPhone. It can store and display gobs of information, but it can’t connect to Google Maps (or whatever brand of map app Apple settled on) unless he gets cell reception – an iffy proposition where we are going. Meanwhile I have an old, primitive handheld GPS receiver (a Magellan Blazer12) that gets it’s signals from the satellites up in heaven. Still, it can only tell me my longitude, my latitude, and which way is north. The b/w lcd display screen is purely alphanumeric; there are no graphics whatsoever. If the Grand Canyon was over the next hill, it would not be able to know or tell me. Now, I figure that if my pal installs some type of US atlas program into his iPod, we could make a winning combination. I would tell him our coordinates, he would plug them into his phone, and boom – we’d know where we are and what’s around us! Assuming there is no flaw in my logic, what atlas program should my friend get? Thanks all, in advance. ---
**Author:** ![astro](https://avatars.discourse-cdn.com/v4/letter/a/9dc877/32.png) [@astro](https://boards.straightdope.com/u/astro)\ **Post date:** [December 4, 2012, 2:00am UTC](https://boards.straightdope.com/t/what-us-atlas-program-should-my-friend-install-on-his-iphone-to-use-with-my-old-gps-receiver/642920/2 "2012-12-04T02:00:50Z")
Re > [@](#): > > He has a new iPhone. It can store and display gobs of information, but it can’t connect to Google Maps (or whatever brand of map app Apple settled on) unless he gets cell reception – an iffy proposition where we are going . I think this is 100% wrong. Must smartphones have GPS antennas and functionality built in See [iPhone 5 and Satellite GPS - Apple Community](https://discussions.apple.com/thread/4288839?start=0&tstart=0) > [@](#): > > As rominggnome showed, the iPhone does have a GPS receiver, and has since the iPhone 3G. And as Rudegar pointed out, the iPhone also has A-GPS capability, which lets the GPS receiver determine its current location much faster than normal. Without A-GPS, the GPS receiver has to wait – sometimes multiple minutes – before it can determine its location, because it doesn’t know where the satellites are. A-GPS allows the phone to download satellite almanac data over the cellular network, so the GPS receiver can immediately know where all the satellites are. A-GPS is not necessary, however, for GPS operation – even if you have no cellular service, you can still use the GPS receiver in the iPhone. I have done this many times, so I have no idea why your friends have had trouble. I recommend the MotionX GPS app, and it works really well out in the woods. You can even download offline map data. > > But what the iPhone does NOT have is WAAS capability. The GPS receiver works by measuring how long it takes for the radio signals to propagate between the satellites and the receiver. The propagation time varies based on the current density of the atmosphere between each satellite and the receiver. Because of the density flucuations, a standard GPS receiver can only get a fix that is accurate to about 10 meters. However, some geostationary satellites transmit atmospheric density information that lets GPS receivers compensate for current atmospheric conditions, and this enables accuracies in the neighborhood of about 1 meter. Garmin has had WAAS capable receivers for years, as have other hand-held and aviation-based GPS receivers, so it is a bit surprising that Apple has not incorporated WAAS into their GPS radio – especially since WAAS density data can be downloaded via the Internet, eliminating the need for increased radio weight. I and others have submitted requests for a WAAS capable GPS receiver in the iPhone, but Apple has not delivered. Perhaps it is because WAAS is only available in North America. However, according to the specs for the iPhone 4S and 5, it now supports GLONASS, which provides near-WAAS accuracy when combined with standard GPS, and is available worldwide. At least that is the next best thing to WAAS. > > Now, the CoreLocation service on the iPhone combines 3 completely separate technologies: GPS, cell tower triangulation, and Wifi-based location. I don’t know the algorithm they use, but I presume that they use whatever service is currently providing the most accurate location information. > > Note that cell tower triangulation has nothing to do with GPS ---
**Author:** ![Disheavel](https://avatars.discourse-cdn.com/v4/letter/d/e274bd/32.png) [@Disheavel](https://boards.straightdope.com/u/Disheavel)\ **Post date:** [December 4, 2012, 5:32am UTC](https://boards.straightdope.com/t/what-us-atlas-program-should-my-friend-install-on-his-iphone-to-use-with-my-old-gps-receiver/642920/3 "2012-12-04T05:32:27Z")
MotionX GPS can download public maps ahead of time such that even without a cell signal and without a data plan, you can still use the maps. It will also use the GPS inside the phone to try and find itself on the maps. Disclaimers: 1. Using an iPhone as a GPS is going to give you about 2 hours of battery life. You are doing the two most energy intensive things on the phone- searching for GPS signals and running a full screen calculation of the map at the same time. a. I would only recommend this as a backup solution. Even using the iPhone to take a picture is going to kill your battery faster than you can imagine. b. I’m not joking about only using it as a backup- unless this is plugged into a car dash don’t do it. 2. The program costs a couple of well spent dollars. 3. The old GPS is worthless unless you set a starting point and just want to find your way back to that point. ---
**Author:** ![Colophon](https://avatars.discourse-cdn.com/v4/letter/c/f05b48/32.png) [@Colophon](https://boards.straightdope.com/u/Colophon)\ **Post date:** [December 4, 2012, 9:14pm UTC](https://boards.straightdope.com/t/what-us-atlas-program-should-my-friend-install-on-his-iphone-to-use-with-my-old-gps-receiver/642920/4 "2012-12-04T21:14:40Z")
> [@Disheavel](#): > > MotionX GPS can download public maps ahead of time such that even without a cell signal and without a data plan, you can still use the maps. It will also use the GPS inside the phone to try and find itself on the maps. > Disclaimers: > > 1. Using an iPhone as a GPS is going to give you about 2 hours of battery life. You are doing the two most energy intensive things on the phone- searching for GPS signals and running a full screen calculation of the map at the same time. > a. I would only recommend this as a backup solution. Even using the iPhone to take a picture is going to kill your battery faster than you can imagine. > b. I’m not joking about only using it as a backup- unless this is plugged into a car dash don’t do it. This is wrong. I often use my iPhone as a GPS on full-day bike rides. As long as you don’t have the screen on all the time you can easily get 8 hours’ use out of it, and that’s if you’re keeping a tracklog. If you just want to fire it up every so often to find out where you are, then you can get much more. I use an app called [ViewRanger](http://www.viewranger.com/en-gb) and highly recommend it. You can download proper topo maps (in tile format so you only pay for the areas you want), or use free mapping off the web. You don’t need a mobile signal to use the maps because they are stored on the phone (automatically for the topo maps; if you want to use the free maps then you just save them onto the phone before you leave cell range). The app plus maps for all my usual cycling areas cost me about £30, and it beats the hell out of the dedicated mapping GPS my friend bought three or four years ago for £350. The GPS track always seems very accurate - when I record a track and later overlay it on Google Maps etc, it perfectly follows the trails I took. This is on an iPhone 4.