Wednesday, May 14, 2008

Cool New Gadget (updated)

(updates at the end of the post)

I like to know where I'm at, especially when I'm hiking in the wilds of Alaska.

I've got an extremely well developed sense of direction. My dad taught me how to use a map and compass at a young age, and I've been an expert at orienteering for most of my life. The Navy taught me stellar navigation and I'm fairly good at it; I even own a decent sextant. Given rise and set tables, compass, sextant, and a decent chronometer I can usually plot a fix and chart a course home without too much sweat. Hell, I can even build a reasonably accurate solar compass in the field, if it really becomes necessary.

But, I'm also a gadget freak. Can't help it, I love technology.

So, for me there's nothing cooler than the US GPS satellite navigation system. I've been using GPS since since the first satellites went up - first in the military, and later when civilian receivers became available to the general public. Naturally, a number of years ago we got into geocaching, which combines our love of hiking and the out of doors with treasure hunting, puzzles, and land navigation. Geocaching, for those of you not familiar with the game, is based on the century-old European sport of letterbox treasure hunting. Basically the way it works is that geocachers hide small treasure 'caches' in interesting places, the caches (usually an ammo can or other such durable weatherproof container) are usually filled with interesting items, some have themes such as a dog friendly trove or child related items, and some are just collections of random stuff. Some are large and some are tiny. All caches contain a log book. Some are placed in easy locations, such as city parks or even sidewalk planters. And some caches are placed in remote and difficult to reach locations. All are well hidden and not apparent unless you are looking specifically for them. There are literally millions of such caches hidden on all seven continents all around the world. Once hidden, the location is recorded using a GPS unit and then posted on Geocaching.com, each post contains the coordinates, a description of the cache, it's difficulty, it's type (the are several types of caches), a map, and clues. Additionally, each post contains comments from those who went seeking the cache). A geocacher logs into the site and searches the database for caches in his or her area, loads the coordinates into their GPS, and goes treasure hunting. When you find a cache, you sign the log book, take one item, and put something back of equal or higher value. It's fun for the whole family and it has taken us to many strange and interesting places that we would never have visited otherwise. I'm a paid member of the game, though you don't have to be. There are advantages to a paid subscription, including special caches and a secret handshake. Being me, I also have a paid Google Earth Plus account, and the Geocaching plugin which allows me to plot caches onto Google Earth - Yeah, I was one of those kids who poured over maps and national geographic for hours on end. For me Google Earth is like heroin.

Anyway, like I said above I've owned GPS units for a long time, starting with one of the very first models, the Motorola TRAXAR, an enormous beast of hideously expensive 80's technology. It took 6 AA batteries and sucked the life out of them in about two hours. It weighed a ton and was like lugging around a brick. It had six receiver channels and took about an hour to plot a position when cold - and it was accurate within, oh, about 300 yards on a good day.

In the early 90's I bought a Magellan GPS350. Much smaller and lighter. It ran on a pair of AA's and lasted about 6 hours or so, depending on a number of factors. It had eight receiver channels (more channels = faster and more accurate fix) and a whole megabyte of RAM. It cost in the hundreds, vice the thousands, of dollars and was reasonably accurate, down to a hundred yards usually. In those days, the Pentagon was afraid the Evil Empire would use our GPS to fly cruise missiles through the windows of the White House and so they implemented something called 'selective availability,' basically a wobble in the satellite timing pulses which induced a margin of error into a receiver's fix datum - therefore the best you could do with a civilian receiver was about a hundred yards, and your fixes tended to move around a bit as the elements of the GPS constellation rose and set. Still that was good enough for geocaching, and the sport was born around that time. The military, or course, had encrypted receivers which filtered out the SA error and were accurate to a gnat's ass.

Somewhere along the line, a couple of smart guys - geophysicists building instruments to measure the slip of tectonic plates - wrote a simple software program to average out the errors induced by SA, and published it to the web. They didn't know that the position errors they were seeing in their receivers were there on purpose, they assumed that the folks in charge of the GPS system were just lousy engineers. They published their program as freeware, and from then on anybody with a laptop and a crappy Garmin receiver could plot fixes accurate within a few feet. It took a couple years, but eventually the Pentagon figured out there wasn't much point in SA anymore, so they turned it off. Along with the lofting of the new WAAS satellites (which broadcast a special signal to WAAS enabled receivers to correct for the natural attenuation and signal bias inherent in atmospheric transmission) this ushered in a whole new era of GPS usage. Cheap, reliable, and very, very accurate receivers became widely available. As such I upgraded to the Magellan Sporttrak Pro around 2001. WAAS capable, water proof, small and light, it was extremely accurate - and it included maps! It had a whole eight megabytes of Ram and could interface with my PC via serial cable and download maps and track data. Very, very cool and I used it not only for geocaching, but for just about every other navigation chore as well. It could find street addresses, show roads, map the boundaries of my property - hell it could even find where I'd left the car in the Disney parking lot in Anaheim.

Last week, though, it crapped out. It's tiny little electronic brain frizzed and the display died a pixilated death. I nearly panicked - not because I'm afraid of getting lost, but because I've gotten so dependent on GPS that I don't want to be without it. So I immediately looked to see what Magellan had to offer in their latest product line - and was seriously disappointed. The company has, uh, declined. They are no longer innovators, and seem to be mired in the past. Here's the thing though, there are two major manufacturers of civilian GPS units in North America, Magellan and Garmin. And for those of us who are GPS nuts, it's a lot like the difference between Macs and PC's. I've always used Magellan and I was seriously reluctant to go over to the dark side of Garmin - yeah, that moral dilemma lasted just long enough for me to read through the abysmal product reviews of Magellan's latest Triton line. So, I headed up to Sportsman's Warehouse to look at Garmin units. I knew exactly how much I wanted to spend and exactly what features I wanted - and unfortunately couldn't find that in any of Garmin's products.

Then I spotted something I'd never heard of - the Delorme Earthmate PN-20. I'm familiar with Delorme, they make some of the best Topographic maps in the world, but I didn't know they'd branched out into GPS. The unit looked like everything I wanted, and then some. I went home and did some research online, and immediately went back and bought it.

I've been playing with it for a week and I've come to the following conclusion: It rocks. Seriously.

It's small and lightweight, water proof and it floats. The case is high visibility yellow (don't think that's important? Try dropping your black Sporttrak in thick Alaskan brush sometime), it runs on a pair of AA's and has very good battery life, and you can use Li-Ion rechargables which the unit will charge from the USB cable or optional power cord. It's got 75MB's of internal memory and takes 2gig SD chips in an integrated card slot located in the battery compartment. It has a high-resolution color display and extremely simple controls and intuitive system navigation. Like most high end modern GPS units, it has an integrated electronic compass, sun and moon tables, fishing and hunting predictors, and can store far more waypoints, routes, and POI's than you'll ever use. And it does something I've never seen in any handheld GPS unit, military or civilian, in addition to detailed topographic and street maps, it can also download and display satellite imagery of the ground you're walking over. That is just so cool, that I can hardly contain myself. But wait there's more - Delorme has included one of the absolute best software mapping packages I've ever seen, and I'm including military software here. Delorme Topo USA 7.0 is PC based (I don't know if they are planning a Mac version or not) and is worth the price of admission all by itself - hell, If I was a Mac user, I'd buy a PC just to run this software. It's a professional level package, not one of those cheap atlas program you can buy at Wal-Mart, or view on the net. When Delorme transferred their high resolution topo maps to electronic format, they lost nothing in detail and not only can you display the maps in normal flat 2D mode, you can also show them in 3D mapping mode with realtime control. In fact you can split the screen and show both displays at the same time. You can add layers to the maps, adding your own information and points of interest. You can upload data recorded in the Earthmate via the included USB cable or the Bluetooth add-on, and plot it in layers over the topo maps. If you load the software on a laptop, you can plug the Earthmate into it and track your GPS position on Topo USA in realtime - this is a powerful tool for people on the road or on the water, for surveyors, for property managers, and the like. The software has a significant learning curve, but there is extensive help both integrated and online, and Delorme includes a tutorial DVD in the package. Overall I've got no complaints about either the software or the hardware. This is an excellent unit at an extremely reasonable price - the nearest comparable Garmin unit is about $300USD more, and doesn't include mapping software, that's a separate purchase. Magellan doesn't have anything to compare and I suspect they'll be out of business sooner or later. The Earthmate retails for around $419, but you can usually find it for about $350. For the next month Delorme is offering an interesting rebate. If you purchase the package for over $299 (up to $420), they'll send you a rebate check for the difference - making the purchase price $299. Period. That's an exceptionally good deal.

GPS Evolution

From the left: Mid-80's Motorola Traxar, early 90's Magellan GPS350, early oo's Magellan Sporttrak Pro, and finally the Delorme Earthmate PN-20. On the computer screen is the split-display 2D/3D Topo USA 7.0 topographic map display showing the Government Peak area of Hatcher Pass, Alaska.

So, bottom line: If you're looking for a really cool gadget or you need a dependable, affordable, and exceptionally advanced handheld navigation system - you're not going to do much better than the Delorne Earthmate PN-20, in any price range.

Get one, and give geocaching a try.


- I mentioned above that the Delorme PN-20 took 2Gig SD chips. And it does - as shipped. However, I neglected to mention that Delorme pushes out regular firmware updates and that if you update the PN-20, the 2Gig limitation is no longer an issue. An updated PN-20 will take all capacity SD cards on up to the new 32Gig SDHC chips. This update massively increases the PN-20's capability to download and store highly detailed regional maps and satellite imagery. There's a couple of ways to do this, if you've got several hours you can download large files via the USB connection, or a much faster method is to plug the SD card into the computer and download directly to that. One minor issue - not all computers, especially older models, can read high-capacity SD cards. You might need to update a driver or two. Just saying.

- Several GPS and outdoor forums and websites linked to this post. For those of you surfing from those links, Howdy and thanks for coming by. So far today there's been almost 600 of you. Feel free to comment. A poster on one forum mentioned that he thought my dating on the beginning of Geocaching was a little off - i.e. he thought that caching began after Selective Availability was turned off. He's right, sort of. Geocaching was around during the SA period, however it was not nearly the phenomenon it is nowadays. Both the world wide web and civilian use of GPS were in their infancy - a bunch of us goofy bastards used to email around caching info, or post it on BBS's such as CompuServe (remember them?). Caching was a whole lot more primitive and had a variety of names and methods back there in the dark ages. GPS would maybe get you within 100 yards of the cache, on a really good day, then you'd have to follow clues in the post to zero in on the treasure. Eventually both the web and the technology improved, SA was turned off, and things merged and formalized and evolved into the sport you see today. And it's still evolving - which is cool. Really, try it, you'll like it.

- Some folks have complained about the PN-20's battery life. I don't know about them, but I've been running this unit on and off since last Sunday, I just drove into Anchorage and back running the unit the whole time - about 4 hours. Figure so far I've got roughly 12 hours on the original Duracell Copper Tops and I'm still showing 1/4 charge left - this is equivalent to what I was getting with the Sporttrak Pro. Battery life though is highly variable, depending on usage. Running the backlit screen all the time will suck significantly more amps than unlit usage.


Follow-up Post: Delorme Test Drive and syncing pictures to Topo USA 7.0.


  1. When we shot Iron Will, we were constantly using Topographical maps to figure out where to look for stuff. Damn I could have used one of those doohickeys.

    Very Cool.

    (Also pretty ironic since my post today was partly about how I don't use GPS much.)

  2. Up here in the wilds of northern Minnesota, GPS is our friend. Except when it isn't. Case in point: In March of last year, the driver of a £96,000 Mercedes relied on her GPS system a little too much and ended up following its directions right into a river.

    "The Mercedes SL500 was swept 600 yards downstream, bouncing from one bank of the River Sense to the other as the woman, in her late 20s and from London, frantically tried to escape," described the Daily Mail. "She was finally rescued by villager Alice Clark when the car ran aground."

  3. "Villager"

    Why am I picturing Alice as an scowling unkempt woman in uncured sheep skins who smells of elderberries?

    Why, Vince, Why?

  4. Oh, and yeah, you've got to be smarter than the tools, just saying.

  5. Well, a little common sense goes a long way. You should probably pay attention to where you're going while using your GPS. And not be so Monty-Pythonish.

  6. If you like wandering around with your gps making tracks and marking up maps, I do hope you join in the effort at OpenStreetMap (more than just streets).

    I've been contributing to it for about a year now, and having fun with it.

    (formerly posted comments as Alex S., but now blogger allows OpenID, yay!)

  7. I could use one of those gadgets! At one point in my life, i taught Map and Compass. However, if truth be told, I was never very good at it. My hubby on the other hand is.(he was also an instructor) He is also the driver in the family, and i am his navigator. This is not a good combination. Case in point..a trip to Ottawa with me as his trusty guide resulted in us ending up in Quebec. Now, in my defense, i was frustrated with all of the one way streets, and so when i finally spotted a road that was going in the direction we WANTED to go in..i jumped at it. How was i supposed to know it was for a bridge that would take us into the next Province.

    Maybe this might find itself on hubby's desk for Father's Day. Might make road trips a lot less stressful. Thanks for the idea!

  8. Cohort, I'd never heard of OpenStreetMap, looks interesting and right up my alley. Thanks for the link.

    Kimby, well, if it's any consolation I've been turned around a couple of times in Ottawa myself - though I didn't end up in the next province.

    Worst city to Navigate around? Honolulu. Way, way, way too many vowels on the streets signs, and all the street names sound the same. A couple of years ago, I was staying in the Hilton on Waikiki beach and giving lectures at a number of Navy facilities, I swear to God even with the GPS unit I couldn't find the places I was supposed to be. Once I somehow ended up on the North Shore and it took me hours to find my way back.

  9. Honolulu. Ohmygawwwwwd. Trust me, I have recently felt your Waikiki pain. It's a one-way-street hell over there. And now I'm definitely going to point this post out to my brother, who thought my navigating sucked!

  10. MWT, I've been to Honolulu a couple of dozen times, and I swear it doesn't get any easier. Somebody needs to buy the state a bucket of consonants... and some kind of logical street plan

  11. Hi there. One of the randomly-linked folks with a technical questions: what is the sensitivity on the model from your experience? I'm a field biologist and I need a unit with < 3m precision at taking and relocating points. Garmin's best one is 10m (personal experiences dictate 1-4m precision), and the Trimbles are $3400.

    Thanks for the post, though! I'm adding this to my stockpile of potential units. I appreciate the time you put into your review.

  12. Beth, thanks and I'm glad you found the review helpful.

    The PN-20 and the latest Delorme PN-40, are both capable of 3M fix resolution - and I have routinely gotten that degree of resolution here in Alaska.

    However, a lot things affect fix accuracy:

    - Number of acquired satellites and their altitudes at the moment of fix - the lower the altitude the more atmosphere the signal has to pass through, which leads to increased signal attenuation and less accurate fix datum. For the most accurate fix, you should have at least six birds above the horizon, and at least four of those above 45 degrees altitude - also note that all the birds are moving, so the instantaneous constellation (i.e. the number of visible satellites and their position relative to you and each other) changes constantly. You fix accuracy can change moment by moment because of this. Normally this isn't enough to affect a 9M fix (the average) but for full 3M fixes you need to be aware of it.

    - WAAS - The Wide Area Augmentation System. This is a differential timing signal, which helps the GPS unit compensate for satellite signal distortion and attenuation. Broadcast from ground stations around most major US airports, and from a pair WAAS satellites. Your fix datum is drastically and reliably improved with the acquisition of a WAAS signal.

    - You need to be out in the open, with a reasonable view of the horizon. The GPS signal is weak and even leaves and medium density canopy cover can affect its reception. Buildings, rock walls, and etc can cause signal reflection and multipath fading - all of which affect reception.

    Overall though, if you're using a consumer electronics GPS like the Delorme and not active-reception military equipment or commercial surveyor type equipment like the Trimple pack - the Delorme is as good as it gets.

  13. Thanks, Jim. The area I'm looking at using has a waystation, so I'm not too worried about cover (plus it's a wide, open space which helps a lot). Sometimes that <3m doesn't pan out that way under normal conditions, however, which is why I asked.

    Thanks for the reply! I think I convinced my advisor to order me a couple for the summer based on your review and the product specs on the website.

  14. Glad I could help, Beth.

    Something I meant to mention, the PN-20 has a visual display - a translucent pink circle - to indicate fix resolution. It expands and contracts in real time on the map window. This is a very handy feature when <3M accuracy is an issue.


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