If you refer to GPS, then you are referring to the Global Positioning System which is satellite-based. Some portable devices have this capability, and it is based purely on signals from high in the sky.

Some portable devices do not have a GPS antenna or receiver, but they do "cell tower positioning" or "cell phone positioning" which obviously use a working cell phone connection. This is based on terrestrial signals that are not high in the sky.

Some people don't know what capability their portable device has, and they don't care... until, of course, when they get outside cell service with a portable device that needs it.

--B.G.--

James,

The iPhone 4 (and I think 3 and 3GS) does indeed use satellite-based GPS. It also uses cell towers to get a quicker fix of where you are when cell towers are available, or if GPS isn't readily available (like indoors). This is called Assisted GPS.

James asks the same questions that confused me when I started my research. Does the iPhone4 really have a GPS chip. The answer is YES.

In Turkey, we used the SIM PIN feature to lock the SIM, so even if there had been cell coverage, we did not receive it. Others have just removed the SIM card to get the same result (the goal being to prevent the phone from draining the battery searching for a signal). We were far from any WIFI. We absolutely had our location showing on our maps, and we could use it to relocate a lost path when we were just 5 or 10 meters from it in dense brush, or to find hidden buildings when we were in white-out fog conditions.

Part of the confusion may be that the iTouch does NOT have a GPS chip.
The WIFI-only-iPad does NOT have a GPS chip.
The iPhone and the WIFI+3G-iPad DO have GPS chips.
If you're not careful when you talk about iThingies, it is easy to get mixed up about what does what.

As I understand it (hopefully Bob Gross, the BPL GPS expert) will chime in here), the iPhone uses WIFI to accelerate the first location fix. Without a WIFI signal, it takes the iPhone roughly five minutes to establish the first location fix after a full power cycle. However, once our iPhone was powered on, we never turned it off, we just put it to sleep. When awakened from sleep, it takes perhaps 10 seconds to get a new location fix (I haven't timed either one, I'm just giving you my impression).

When I went to the Apple store to buy my iPhone, I told the sales agent that I didn't actually care about the phone, I was just buying it as a GPS device, and the agent assured me that it would not work. Totally confused, as I had read many forum posts about it already, I bought it with the 30-day-return assurance. The first thing I did was remove the SIM card, turn off WIFI, and head out to the baylands where there is no WIFI anyway. It worked just fine. I returned to the Apple Store to tell the Sales Rep about it, and the other reps concurred that the GPS chip works just fine without WIFI or cell, and the one rep was misinformed. I tell this story to illustrate how hard it can be to sort this stuff out.

James, you said " I tried to get a fix on the Washington coast using the standard maps program and got nothing" -- I wonder if you were getting a GPS fix just fine, but could not see it because the standard maps program does not store maps for offline use. This is the essence of Ken's article -- you need an app that allows you to pre-download the maps for offline use. If you have an iPhone and you're in the US, then invest 8 bucks to buy Topo Maps. If you think it was a waste of $8 send me a PM and I'll buy you a drink! (this offer applies only to James, not to everybody!)

Keep asking questions and I'll do my best help out. AmyL

PS, my understanding is that iPhone3 has a GPS chip but it is not as powerful as iPhone4's GPS chip, but that is rumor I can't substantiate.

Edited by drongobird on 07/27/2011 18:24:21 MDT.

I used both Backcountry Navigator and Gaia on my recent AT hike. I never could get BN to load a track I had but it loaded waypoints fine. Both worked reasonably well but I think I prefer the interface on Gaia.

Battery life on the smartphones is definitely a concern. I ended up purchasing 3 additional batteries for the trip and my Thunderbolt sucked them dry. I only used the GPS occasionally and otherwise kept it in airport mode with all services disabled.

If battery life can be improved the full-featured phones will really be giving standalone GPS units a run for their money.

@Cary,
I suspect the Android battery drain may have similar issues to iPhone, and wonder about your experience.

With the iPhone, it drains 5% per hour battery if you are in Tracking mode. So Tracking is not viable for multi-day trips unless you have a battery recharge solution. And it drains 1.2% battery capacity per hour (30% per day) searching for a cell signal when one is not present. So it is essential to disable the phone (how-to info). You said you were in Airplane Mode, so that should turn off the phone.

Do you know what your baseline daily drain is, i.e. with all functionality disabled and the device sleeping? It took me many dozens of hours to figure out how to get the baseline battery drain down to 1% per day on the ATT iPhone4. If somebody has done that research for various Android model phones, that info is golden.

Amy

Edited by drongobird on 07/28/2011 07:23:07 MDT.

"As I understand it (hopefully Bob Gross, the BPL GPS expert) will chime in here), the iPhone uses WIFI to accelerate the first location fix. Without a WIFI signal, it takes the iPhone roughly five minutes to establish the first location fix after a full power cycle. However, once our iPhone was powered on, we never turned it off, we just put it to sleep. When awakened from sleep, it takes perhaps 10 seconds to get a new location fix (I haven't timed either one, I'm just giving you my impression)."

The five minute wait would be called the Time To First Fix -- Cold. In my opinion, five minutes is abnormally slow, and I would avoid that. It might be related to getting an entire new GPS Ephemeris from the satellites, but that can take up to about twelve or fifteen minutes. You can get a fix without a current ephemeris, but it will have some additional position accuracy error for a while. But, you don't know that.

If you have used the device recently, then it has its last position in non-volatile memory, and it uses that to speed up the current fix. So, you get TTFF -- Warm. That ten seconds seems quick. But then, you don't know exactly how much error it has at the ten second fix.

If the device uses cell phone tower signals to assist its fix rate, then that is nice. Unfortunately, I have dealt with too many cell phone companies over their synchronization equipment at towers, and most of them cut too many corners. It is one thing to have technology, and it is another thing to have technology that is actually working the way that it is supposed to because they know the end users don't have the accuracy to confront them about anything.

Don't ask me much about iThingies. I wouldn't buy an Apple product on a bet.

--B.G.--

Some very good advice above. A number have mentioned that “Tracking is not viable”. I have found that with the addition of an external lithium battery pack it becomes quite viable. I was playing with this so that I can save a .gpx route of my trip and geotage photos.

I just finished 4 days in Scotland with my son. We did about 8-9 hr days of walking with my IPhone on all day recording our route. With many of the power saving tips above in place, I was easily able to use my iphone the whole trip. I was using the Mini Gorilla Battery pack (9.4 oz), and I suspect with the amount of power left in it, I could probably have done about 7 days.

My setup is an Arctic C1 mobile charging unit. This unit has a solar panel, along with a small internal Li-ion internal battery. Basically, you place this unit out in the sun all day (or I suppose it could be attached securely to the outside of a pack) where it charges the internal battery. Then at night in camp you plug your phone into it, and the phone charges from the Arctic C1 unit. The Arctic C1 solar charger is listed at 52g, or about 1.8 ounces, and can charge most mini-USB or micro-USB phones. Almost all Android phones are micro-USB.

I'm taking my HTC Nexus One phone as my only GPS device.

This is my untested plan of action for a pack trip I'm taking in a couple of weeks. Note that I have other hikers in my party with conventional GPS units, so I'm really not being brave.

Since I'm an Android user, I'm going to purchase Backcountry Navigator - I've already tried the free version, though not extensively.

Like an earlier post, I find that a smartphone is an excellent ultralight device, as it serves as a camera, music player, alarm clock, note taking device, and of course, flashlight. That's a lot of devices, and when you add them together, you may find you are saving weight!

I have to make a shameless self-mention too, since I'm the Android developer of a flashlight app (Brightest Flashlight Free), but you don't need to install mine, there are lots of other free flashlights available for Android. They use the camera LED as a light source, which is super bright.

I'll second that.

Amy has written up some great tips. I did not cover this area because I knew that an article covering this material was coming and we wnated to avoid overlapping too much. I'd add that dimming down your screen helps quite a bit too. Extra battery solutions abound for smartphones and range in effectiveness (I'd love to test the NPower PEG sometime but I don't think that's going to happen anytime soon). This is also talked about to a degree in a forthcoming article as I recall. Personally I carry a Powermonkey batery or two with me on trips. I don't generally bother with the solar panels I have for them as I have found them to be of exceedingly limited value. On a longer trip I bring the proper charging tips/plugs and call that enough.

Battery life is still the biggest limiting factor besides screen size to making smartphone mapping/navigation useful. But as Amy has pointed out with careful monitoring of your battery you can get a great deal of lifeout of your device.

John, you're right apps like the built-in Google app requires an internet connection but as I note in the article (and others have in the thread here) the apps discussed all let you download the maps they use to the device itself. A note of warning about downloading maps over a cellular connection: they're big. If you are travelling outside your normal calling region (e.g., internationally) keep in mind that you will take a big data hit downloading any maps. I accidentally did this a few times while in Tenerife last January and the data hit was tens of megabytes. When you consider the gauging cell companies charge us for data when abroad you can imagine how big a bill that can easily turn into. You can reduce the data load somewhat with services like Onavo (I've played with it a bit and will learn a lot more about its effectiveness I expect when I visit Turkey this fall) but even so if you can get your maps at home or over WiFi you will be much better off.

One last thing: their are so many applications out there that I can't pretend to know them all. Until I started reading this thread I had not heard of either Maplets or iPheGeNie. I didn't even really touch on apps like Galileo (though I think it will be touched on by another article). This is a fast moving area for iOS and Android and I don't think it will slow down.

James, the iPhone does have a GPS receiver in it. In fact, pretty much every cell phone today made has a GPS receiver. The iPhone will, it is true, and depending on the app start out trying to get a location based in triangulation of cell tower and WiFi signals but once a GPS signal lock is achieved it happily uses that to fix position. The iPhone 4 uses a chip from Broadcom. It's an A-GPS chip and this may be what is confusing you. A-GPS (Assisted GPS) can improve GPS startup time and time to first fix times by obtaining information from the cell network about orbital positions of the GPS satellites. It can do some other things to but this is the most common use in all probability.

The limitations of a cellphone based GPS system probably have more to do with the antenna used than anything else. This can slow down signal acquisition and limit accuracy compared to what you could get with a modern dedicated handheld unit. However, if you can't get by with 10 meters of accuracy then you really need to consider improving your navigation skills and I am saying that as someone who has low vision.

Like any GPS device a smartphone will acquire a good singla more quickly if you remain stationary. And, again like all GPS devices, if you are trying to get a signal and it has been quite some time since you last used the GPS and/or you have moved quite a distance from your last location acquisition will take longer. If you are in a location where A-GPS can be employed that will be mitigated somewhat. This is why, for example, I have found the geotagging of photos taken with the built-in Camera app are sometimes quite a bit off. The GPS hasn't gotten a solid lock at the time of the taking of the picture. But if you are using a GPS app like any mentioned above this is not going to be an issue. You'll know when you have a signal as the app will tell you.

I've been using the Gaia GPS in my old school iPhone for a couple of years -- I think I got an early version for free, then bought it as it improved. It works in Alaska out of cell service. I've used it from Southeast to the Aleutians to north of Nome.

I really appreciate the ability to download topo maps for all of Alaska. Gaia has great customer service and is pretty easy to use. I have had some issues with tracking and unwanted waypoints, but that might be dysfunctional thumbs.

I just started testing GPS Kit last week. Today they released a new version that makes significant improvement to already great app. And they lowered the price from $20 to $10. Don't know how long the price will be down.
If you're an iPhone GPS/Map user and you don't have this app already, you might want to grab it at the lower price. I'll finish updating my list of apps in the next few days, but so far it looks excellent.
http://dl.dropbox.com/u/15393086/BPL/iPhoneGPSapps.htm

Highlights of GPS Kit:
Map sources: OpenCycleMap, Bing and Google maps.
GPX/KML import and export: excellent
Track creation and stats: excellent.
Ease of Learning and Ease of Use: excellent, on par with Gaia, better than MotionX.

Compared to Gaia GPS -- it doesn't offer USGS maps, important for north america.

Gaia GPS worked pretty well for me on a recent expedition to Alaska. I downloaded USGS My Topo maps to the phone before leaving. Several of the places we went had significant glacier activity and the old USGS maps did not always match with our surroundings.

The CDMA based Verizon iPhone 4 has a huge handicap compared to the AT&T version in that there is no way to disable the cellular radio (no SIM card to remove). GPS does not work in Airplane mode and the phone is always looking for service at maximum transmit power when using it as a GPS. This drains the battery pretty quick. The phone usually locks in a position after about a minute or two once out of Airplane mode.

I was able to use it for about a week with a couple of position checks a day but would for sure still rely on the good old paper map and compass as primary navigation.

There's a new mapping app out there: National Geographic's Trail Maps app. These are NOT trail maps, but are USGS 1:100K and 1:24K topo maps, as well as satellite photos from Bing, covering the lower 48 states of the US. The app is super-easy to use, reasonably fast, and you can download (large) sections of quads and photos for off-line use. The quads are reasonably high resolution, better than NG's state TOPO! products for Windows and Mac. It's not as full-featured as the Topo Maps app, but for $3, this is a good deal for mainland US users.

http://itunes.apple.com/us/app/trail-maps-by-national-geographic/id450588743

Agree with what Douglas said. National Geographic Trail Maps looks like a great first version. It doesn't yet import or export gpx/kml files, but I suspect that is probably coming soon. The feature set is not nearly as nice as Topo Maps or Gaia (which also include all the USGS 1:24K maps), but it does include satellite imagery, which is fantastic. Beware! It has the battery drain bug that I've seen in several apps (I've sent them a note but haven't yet heard back, hopefully they will fix it.)

Lots of app news in the past couple weeks.
GPS Kit released a new version with fantastic improvements to map downloading. It's really shaping up to be a great product.

Gaia GPS has fixed the battery draining bug, and the terrible "disappearing track" bug (which has been in the product for the past 8 weeks). The fixes are in V5.2 which should show up in the app store any day now.

ViewRanger -- I finally tested ViewRanger. It is the absolute worst for draining the battery, not viable for backpacking in my opinion.

I've updated my table of iphone gps apps with info about all four of the changes mentioned above. And the "battery draining bug" info is in the table too.

I also updated the article about using iPhone as Backpacking GPS/Mapping device with some relatively minor changes.

And a final note, I've been using Maplets a lot this past week. No new news here, but I'm coming to love this product. If you have an iPhone and don't have, you should definitely invest a couple bucks and add it to your suite of tools. Very useful in many ways.

AmyL, Palo Alto
amyl.smugmug.com

Edited by drongobird on 08/15/2011 17:40:46 MDT.

I downloaded the Maplet map of Japan to my iPhone, and was pleasantly/annoyingly/perpexidly surprised when all the listed cities and fiefdoms of the Edo period showed up. Seriously? There have been a few road changes in the last 500 years!

Miguel - glad you tried it! Yes, it's a different kind of app. It doesn't replace the standard gps/map apps, but complements them. Odd that the first map you downloaded is a historical map :) When I search for Japan, I get only 23 maps, a very thin inventory.

You've probably figured this out, but for others...
Maplets hosts maps of all sorts, and provides an interface with which users can easily find and download the maps. It then displays the map, and, when the map is drawn to scale, it is georeferenced and shows your location on the map.

In the US, all of the national parks, all state parks (for many states), most of the National Forests, and hundreds of local parks are available already. Also cycleway maps, and transit maps. Maplets is busy adding more maps, and they are very responsive to requests. I don't know them, but I suspect they'd be thrilled to get leads on maps of parks in Japan that should be added, you just need to send them a url to a site where they can access the source material (and of course it needs to be legal for them to republish it).

I got an account from them, and I added my first map to their inventory. It's a specialized map of San Francisco Bay that shows the numbering scheme of the salt ponds - very useful for birdwatchers but probably not interesting to anybody else. I used to use the map as a simple pdf file, but when Maplets hosts it I can see my location on the map, a big improvement!

Miguel - Jim and I are strongly considering a hiking trip to Japan next spring. I'd love it if Maplets had more maps of Japanese parks in the inventory! There must be a pdf map for every national park in Japan, that would be a great place to start!

Or maybe these folks would give permission to add their tourist maps to Maplets. http://www.infomapjapan.com/sitemap.phtml

Cheers, Amy

Edited by drongobird on 08/15/2011 19:52:44 MDT.

What is the business model for Maplets?

In other words, how does it make a buck?

--B.G.--

BG asked how does Maplets make a buck. I'm just guessing here, as I don't know anything about them except that they added the maps I asked for and they already had the first 20 maps I wanted to use (Point Reyes National Seashore, Los Padres National Forest, Palo Alto Foothills Park, Inyo National Forest, etc).

You can go to their website to see what maps are already available without needing to buy the app first. Search for something like "National Park", "National Forest", or "San Francisco" to get a sense -- http://www.mobilemaplets.com/places?display=list

If you're using the app, you can search (just like on the website) or you can show the available maps displayed on a map, making it easy to find nearby maps without knowing the right terms to search.

The app costs $3 or $4. There's no advertising, so they get no income from advertising. All of the maps that I've downloaded so far are government agency maps, for example the VTA Transit System map or the National Park Service maps. Those maps are free for the taking in paper or pdf form, and I suspect the government agencies are thrilled to get them out into users hands without having to pay to print them. So I suspect the "source material" has no cost.

The app itself is quite simple. Just looking at it, I doubt there are more than a couple programmers involved, possibly just one, probably little marketing effort, not much user documentation needed. They have to pay for servers to host the maps, but the traffic on the servers is very light, since you just download a map and then use it offline; it doesn't incur heavy traffic like many apps have to deal with. It's a really nice concept - not complex to implement, easy to scale it up.

AmyL

Edited by drongobird on 08/15/2011 20:13:24 MDT.