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Reviews > Navigation and Map Gear > GPS > Delorme Earthmate GPS PN-20 > Test Report by Edward Ripley-Duggan

August 2, 2007





NAME: Edward Ripley-Duggan
AGE: 54
LOCATION: Catskills, New York State
HEIGHT: 6' 1" (1.85 m)
WEIGHT: 215 lb (97.50 kg)

I enjoy walking in all its forms, from a simple stroll in the woods to multi-day backpack excursions. Though by no means an extreme ultra-light enthusiast, from spring to fall my preference is to carry a pack weight (before food and water) of 12 lb (5.5 kg), more or less. In recent years, I've rapidly moved to a philosophy of "lighter is better," within the constraints of budget and common sense.



Manufacturer: DeLorme
Year of Manufacture: 2007
Manufacturer's Website:
MSRP: US$449.95 for deluxe bundle version (regular price March 2007, from manufacturer's literature)

The GPS unit
Contents of basic GPS package: GPS receiver, neck lanyard, manual, USB cable, 2 AA batteries, plus Topo USA version 6.0 (see below) and various notices etc.
GPS casing: IPX-7 waterproof, impact resistant [so stated by manufacturer]
N.B. The IPX-7 standard is defined as "Protected against heavy seas - Water projected at all angles through a 12.5mm nozzle at a flow rate of 100 liters/min at a pressure of 100kN/m2 for 3 minutes from a distance of 3 meters." This is handy to know for sea kayaking!
Color: Yellow and black
Stated dimensions: 5.25" x 2.43" x 1.5" (13 cm x 6 cm x 4 cm)
Measured dimensions: My measurements are congruent with those of the manufacturer, allowing for the awkward shape
Listed weight, without batteries: 5.28 oz (150 g)
Listed weight, with 2 AA batteries: 7.04 oz (200 g)
Measured weight, without batteries, including SD [Secure Digital] memory card: 5.25 oz (148 g)
Measured weight, with 2 AA batteries, including SD card: 7.25 oz (206 g)
Measured weight, with supplied lithium-ion rechargeable battery, including SD card: 6.75 oz (191 g)
N.B. The measured weights are subject to the approximately .2 oz (6 g) tolerance of my scale.
Screen size, stated: 176 x 220 [pixels] daylight-readable TFT [i.e. "thin film transistor liquid crystal display"]
Screen dimensions, measured: 1.7" x 1.4" (4.4 x 3.5 cm)
Batteries: 2 AA, or lithium-ion rechargeable battery
Memory: 75 MB user-available internal flash memory
Extended memory: Will accept SD (Secure Digital) cards to 2 GB capacity in slot behind battery
Supplied extended memory: One 1 GB SD card, with USB 2.0 SD card reader
Manual: 83 pages, included

I have avoided quoting the full technical specs here, as to most readers this is mere jargon (much of it for me too, I may add). For those who wish to know details of the chipset etc., I recommend the DeLorme website. However, the following are likely to be of general interest.

Operating temperature range: -20 C to + 70 C (-4 F to 158 F)
Storage temperature range: -40 C to + 85 C (-40 F to 185 F)
Antenna: Built in [i.e. no port for external antenna]
Data storage: Up to 10 tracks (10,000 points per track), 1000 user-defined waypoints. 50 routes

Topo USA Version 6.0
Companion software, from plastic case containing the program on CD and the US map database on DVD. Included is a certificate for the download of up to $100-worth of DeLorme's Aerial Data packets (for up to 400 sq km, 154 sq mi). There's also a small correction slip, as the packaging mentions the wrong figure for the area of the downloadable data. This software and the downloadable data (USGS quads, satellite and aerial imagery) come as standard issue with the GPS as offered by DeLorme, both in its basic form and in the two bundled versions. These are the "Travel Power Kit Bundle" and the present "DeLuxe Bundle," about which more in a moment. There is a manual in PDF (Portable Document Format) form included as a file on the disk, but (other than a folding sheet with a "quick start guide" to assist with software installation) no separate printed manual for the software.

Contents of the Deluxe Bundle
In addition to the items noted above, the Deluxe Bundle contains the following. I have (with the exception of the rechargeable battery) not weighed these various peripherals. Most are power supply cords of various kinds, plus the SD card and card reader. They comprise a comprehensive but slightly confusing array, and are unlikely to be carried on a backpack, when simple replacement AA batteries will suffice.

CR-V3 lithium-ion rechargeable battery
Charging battery pack for the battery, with both A/C and 12-volt in-vehicle cables
Special eight-pin-to-mini-USB connector for the PN-20, required for charging the Li-ion battery inside the GPS
12-volt in-vehicle cables, which connect the connector listed above
LCD protective film kit with three screen protector films and one microfiber cloth
1-GB SD card
USB 2.0 card reader
Black nylon ditty bag for storing all of the above
Explanatory sheet

The DeLorme Earthmate GPS PN-20

The unit was received well packaged and in sound condition. The GPS receiver, manual, software and two AA batteries were housed in an attractively printed box, which lists many of the features (both basic and technical) of the GPS unit and the software. One point of note is that the box states that a certificate for 400 square miles of downloadable imagery is included. This is an error, as is noted on a paper slip included in the Topo USA box. The correct figure is 400 square kilometres.

The "Deluxe bundle" was separately housed within the package. A very convenient black nylon pouch is included with this, which holds all the various appurtenances once they are unpacked. This is a good thing. There are a lot of them, some of which are indistinguishable from the various other chargers, cables etc. with which our lives now seem festooned, so to have a container solely for these is a plus!

As with most such devices, the DeLorme warranty is a bit more limited than that for most outdoors gear, although in line with warranties for consumer electronics. If desired, the warranty can be examined in full on the website (or in the manual), but the gist is summed up in the first two paragraphs:

"DeLorme warrants that your Earthmate GPS PN-20 will be free from defects in materials and workmanship for 1 year from the date of purchase. If your Earthmate GPS PN-20 fails in normal use, DeLorme will, at its sole option, either repair or replace the unit. DeLorme reserves the right to either repair or replace the unit with a new or refurbished unit at its sole discretion.
Such repairs or replacements will be made at no charge for labor or materials; however, the customer will be responsible for any shipping charges incurred to send the device to DeLorme. The repaired or replaced product will be warranted for 90 days from the date of return shipment, or for the balance of the original warranty, whichever is longer. This warranty does not cover failures due to abuse, misuse, accidents, or unauthorized disassembly or modification. Any repairs not performed by DeLorme will void this warranty."

What is left a little unclear is how out-of-warranty service is handled, and I'd love to see the manual's text improved to clarify this. A GPS is a long-term investment, and I would certainly like to know details on out-of-warranty care.

Initial Impressions
While I was not an especially early adopter of GPS technology, I have owned one for six or seven years, and I'm reasonably familiar with a fairly wide range of handheld units. As to software, I've owned another DeLorme product, 3-D Topoquads (now in version 2.0) for perhaps ten years. I mention this because my perceptions of the product will unavoidably be those of a fairly experienced user of both GPS and basic mapping software.

The PN-20 has proved easy for me to operate. In part this is because of the way the firmware (the operating system for the unit) is designed. There's not much functionality that's buried away below many tiers of menus. An additional reason is that the controls have a pleasing crispness to their operation. A button-press is accompanied by a gentle electronically-generated click, which provides useful auditory feedback. I have even used the unit wearing gloves (and not especially light ones, at that). The clarity and resolution of the screen display is excellent, as is the brightness, which is fully controllable, another key factor in ease of use.

I had batteries loaded and my first GPS location fix within a half-hour of having unpacked the unit after receipt. By the following day I was using it to create a track with occasional waypoints, when I took several hours off to do a backcountry ski jaunt. Certainly, for anyone with some exposure to GPS technology, learning to use the PN-20 shouldn't be much of an issue.

At this point, let me sound a gentle note of caution regarding GPS units in general. The GPS technology is revolutionary for navigating, no ifs, ands or buts. Still, when I'm in anything approaching serious backcountry terrain (which, the day of the ski tour I mention, I was not), I orient myself in the traditional manner: by use of map, compass, cues taken from the terrain, and common sense. My GPS is usually with me, and I may use it to track my progress for later examination, or to mark (waypoint) the locations of anything interesting that I see so I can return to those points in future. I'll certainly reach for it, if it's handy, to help untangle a navigational error, but I do not rely on it. The GPS is a powerful navigation tool, but I feel very strongly that anything that can go wrong or lose power should never be the sole, or even the primary method of wayfinding on difficult terrain, in circumstances where the consequences of equipment failure could be serious. Here endeth the lesson...

The PN-20 is quite a bit chunkier, and marginally heavier than the GPS I have been using. That's a black-and-white model, and the color display (and brightness) of the DeLorme model were something I found impressive from the outset. Unfortunately, owing to a defective program installation disk I was unable to upload maps until I received the replacement disk several days later, but even without that feature operational, I found being able to see my track on the screen, so easily discernible in color, distinctly useful. While I was out that first day I saw a fisher, a very large member of the weasel family and the first I'd ever seen in the wild, and it was a pleasure (and a nice baptism for the unit) to waypoint the spot.

On a final note, the PN-20 was generally very much what I had expected from DeLorme's literature about the unit (which I had, as an existing customer, previously received by mail), and from their website.

Quality of instructions
As with any piece of electronic apparatus, the manual is key to understanding how to operate a GPS. The PN-20 manual is, in my estimation, well-written and comprehensive. There's a useful "Getting Started" section, with the basics of battery installation and turning the unit on for the first time. The functions of the buttons are described here. There is, rather surprisingly, no diagram of the front and back of the case, but as the buttons on the unit are generally labeled or otherwise fairly obvious, this may have been deemed unnecessary. although if I were a beginning user, I might consider this a shortcoming. A labeled view of both front and back is shown in this report. Various other basics of operation are discussed in this introductory section of the manual.

After this, there's a section of "Scenarios." This is an excellent idea. Before the nitty-gritty details, this shows how the GPS can be used in three real-world settings. The activities selected are geocaching, bird watching, and mountain biking. These examples of how the GPS can enhance (or, in the case of geocaching, enable) these pursuits was, I found, very helpful. This was particularly the case with geocaching, which is an activity I have not pursued up until now, and which I intend to investigate while I test the PN-20.

The balance of the manual describes the operation of the GPS on a screen-by-screen basis. Using a book metaphor, DeLorme terms the various operational screens "pages," pretty much standard terminology with GPS units. The margin of the text in this section of the manual provides screenshots as well as some helpful hints, highlighted in boxes.

I found the manual useful in answering a number of questions. The only caveat that I have is that it isn't as well indexed as it might be. However, it may also be downloaded from the DeLorme website in PDF form, and it can then be completely searched on any word using Adobe Reader's search functions. I've saved that to my desktop.

While the contents of the Deluxe Bundle are mostly pretty obvious, I felt the documentation to be a little skimpy, but overall adequate. There is a printed sheet identifying the various components of the Travel PowerKit, together with instructions on how to insert the charged lithium-ion battery, and how to use the charger itself. This did leave me unclear on a few points, for example whether there is there any reason why the plug prongs on the charger unit can't be used instead of attaching the AC adapter? However, this is hardly crucial, and the documentation is sufficient.

Customer Service
As the installation CD for the Topo USA software proved to be defective, giving me CRC errors galore and preventing me from installing the software, I had to call DeLorme's technical service for a replacement. I was quickly routed to an operator. The subsequent wait for a service technician turned out to be almost twenty minutes. With a new product and a probable high volume of calls, this delay was not unexpected, but the response would ideally have been swifter. The technician, once I got through, was very helpful and courteous. I was not able to disguise the fact that I was with BGT, as I needed to give an invoice number. Having said this, he was perfectly obliging beforehand, so I have no reason to think this revelation had any effect on the outcome of the call! I received the new disk a few days later. I have since had a couple of other occasions to contact customer service, and the technicians have been unfailingly helpful. If they read this, thank you.

Operation and Features

It's beyond the scope of this test to provide comprehensive instruction on the operation of this GPS, or a description of the technology of GPS in general. For the first, I recommend the PDF version of DeLorme's manual. For the second, there's a wealth of information on the Web on all aspects of the technology, from Antennas to WAAS (I tried to think of a GPS term beginning with "Z," but failed). Still, I do want to familiarize readers with the basics of operation of the PN-20, so I can intelligently discuss my experiences with the instrument. The controls of the unit, its buttons, pages and menus, are not that different from many models of GPS, although (in my estimation) the PN-20's ability to take on board maps and imagery puts it in a whole new category.

First, here's the front panel of the GPS, with labels that briefly describe the functions of the buttons. Bear in mind that the function of some of these varies slightly according to the page/screen that's being used.

Front panel of GPS

To power the GPS on, the small red "Power" button is held down for a moment (the manual states for 1.5 seconds), and then released. The DeLorme boot screen shows briefly, followed a few seconds later by the Satellites page. The GPS immediately starts to acquire satellite signals. Once on, if the "Power" button is held down for about 2 seconds, a slider bar appears, which enables the screen brightness to be altered. If the button is just pressed briefly once while the unit's on, the "power down" screen shows. When the Enter key is pressed subsequently, the GPS will turn off. This two-button shutdown seems to me to be a good idea, as it prevents accidentally shutting the unit off, although it's a bit surprising that there's not a similar protection against turning it on. Holding the key down for 7 seconds resets the GPS.

Details of back of GPS

Above are two views of the back of the GPS case. On the left, the back is shown held in place with two D-rings. These are attached to brass screws, and turning the rings clockwise fastens the back tightly. Once the back is screwed in place, the D-rings fold down flush and are retained in position by two small projecting plastic ribs. To install the AA batteries (or lithium-ion power pack) and the SD card, the back must be removed, to expose the battery compartment (image on right). To install the card, press on the small bar marked "PUSH." This releases the SD slot, which then swings up (it is shown deployed in this fashion in the right-hand image). The card slides into position, with the contacts going in first and facing the interior of the GPS (i.e. with the label on the card facing towards the user). Holding the battery release ribbon out of the way (it tends to get in the way) the slot is then pushed down until it clicks into place. The batteries may then be installed (polarity as indicated in the diagram). The back is then replaced using the screws attached to the D-rings, which are folded then folded flush. The GPS is now ready for operation.

When I turned the GPS on for the first time (using the two supplied AA cells, as the lithium-ion battery was not yet charged), I was quite surprised at how quickly the unit provided an accurate first fix on my location. I confirmed the accuracy in a mapping program, by punching in the coordinates (the Topo USA basemap for my area was not yet loaded because of the defective installation disk). A card laid into the manual states that the process may take up to ten minutes the first time used. I had a solid fix in about forty seconds, a figure closer to what the manual states is normal for a warm start, i.e. with much information (ephemeris, almanac, approximate time, partial position) already present in the unit from previous use. It's possible that the unit was tested in the factory, which would have resulted in a faster first fix.

This speedy start may have been an anomaly, but I have been consistently impressed, during my preliminary use of the PN-20, by the speed of signal acquisition. It's generally capable of getting a location swiftly even inside a building or in dense brush. As yet, there are no leaves on the trees, but based by the quality of satellite acquisition I am able to get on the ground floor of my house, I shall be surprised if the heavy woodland canopy of the spring and summer Catskills will cause any significant problems with reception. I'll report on this, as this is an important consideration with any GPS in the woods of the eastern US and elsewhere.

GPS pages
In order to give a sense of what it's like to use this GPS, what follows are a list, with comments, of the main pages of the GPS, together with a description of their layout and function.

Satellite page
The satellite page is shown displayed in the first image above (that of the front of the GPS unit). This is the screen seen after the GPS has booted. Unless the GPS location function is turned off from the Setup menu (this can also be done by using the Menu button directly from the Satellites page), the top section of this page shows a circular view of the sky with superimposed directions (North up), with approximate satellite positions. Below is a graph showing which satellites are available, and the signal strength and status of each. A blank means that the satellite is not yet being received. Red indicates that it is being tracked, but no data has yet been received. Green indicates that the satellite is being tracked, ephemeris data is being received (one of several data streams from the GPS satellites), and the satellite is being used for navigation.

Blue means much the same, but indicates that additionally the satellite being tracked is providing WAAS correction, a technology that enhances the accuracy of GPS position fixes. I have found that the mere fact that the WAAS satellite (marked as satellite 138 by the GPS, here on the East Coast) is shown as being tracked does not, apparently, mean that WAAS correction data is being received. According to DeLorme's manual, when WAAS correction is in operation, the letters "WAAS" show at the top right of the screen, something I have not often seen so far. When it works, almost all of the satellite strength bars in the chart turn blue. The increase in accuracy that I've noted is not especially dramatic. It increases from (say) +/- 40 ft (12 m) to perhaps +/- 15 ft (5 m), the latter being about the best fix I've seen so far. This is a worthwhile improvement for some purposes, but for general navigation (rather than identifying a very specific location) it may not justify me enabling WAAS all the time.

The satellite page also shows the quality of fix (what DeLorme refers to as 2-D and 3-D, which depends on the number of satellites monitored), as well as the accuracy, expressed (as noted above) as a tolerance: +/- [distance in feet or meters]. The font used to display accuracy and fix type is, to my mind, badly chosen. It's an outline font, which for those of us with less than 20/20 vision is generally harder to read, especially when it's in a small point size. Fortunately, much of this information can also be made available in the Trip Info page, if desired, but it would be really helpful if DeLorme would use a more legible font for this data.

The bottom of the screen has a bar that indicates battery strength. For this to be accurate, it's critical that the correct battery type is selected in the Setup page. If the wrong type is set, the battery life shown is highly misleading. For example, if the indicator is set to "lithium-ion battery" and a pair of standard alkaline AA cells are used, the battery life will be shown as almost exhausted from the outset.

Map page
This is the heart of the GPS, its raison d'être. The Map page has an extraordinary wealth of options, not all of which I am able to touch on here. All of the configuration is done via the Menu key, which provides access to three page-specific items: "Show info fields," "Measure distance," and "Map setup." The GPS has a pre-programmed world highway base map (I'm using DeLorme's designations for the various map types here). This is hardwired into the unit, and provides only the most basic data. Shown are major cities, coastal outlines, and main roads. For the US, only Interstates are labeled on the map, but the names of other main roads are displayed if the map cursor is "panned"—moved using the arrow keys—over the road, whereupon the road name is displayed at bottom left. This map is useful only for the most rudimentary kind of navigation, primarily city-to-city.

All remaining types of map data must be uploaded to the GPS (or, more accurately, to the SD memory card, which is where such maps are stored). It's far quicker to copy map data, prepared in the Topo USA program, directly to the SD card using a card reader plugged into an available USB slot. The alternative is to upload using the GPS unit's USB-port cable, which is slow as molasses. This is much better suited for download of tracks, routes, and waypoints to the computer from the GPS.

Even so, for large map files, this can be a slow process, but this limitation is largely inherent to the type of storage: writing to SD cards is not especially fast. However, they are cheap, and they have a conveniently small form factor. I moved about 900 MB of map data to the card using the appropriate screen in Topo USA. It's also possible, and maybe a bit faster, to use the Windows "drag and drop" method of file transfer. As it was, the process took over an hour. However, this transfer gave me all the USGS quads for the Catskills, as well as the DeLorme Street and Topographic map, an enormous amount of map data. Clearly, though, if I'm going to have maps and imagery for several such extensive areas, it's going to be most convenient to purchase a number of high-capacity SD cards (the unit will handle up to 2 GB), and swap these in and out as my travels dictate. Such cards are now cheap.

The Topo USA software package offers two types of map that may be uploaded. These are regional routable maps (part of DeLorme's Street Atlas USA dataset, designed primarily for automobile navigation) and DeLorme Street & Topographic, a high-resolution contoured map, suitable for serious navigation. The remaining three supported types of map data are USGS 7.5-minute quads, DOQQ (USGS Digital Orthoimagery Quarter Quadrangles) aerial imagery, and satellite imagery ("Sat 10 data" i.e. with 10 m, 33 ft resolution). These last three types are available for a fee, and also require Topo USA for purchase and preparation. While a certificate for $100-worth of downloads is supplied with the PN-20, after this has been used up such map imagery must be purchased. I was pleased to find that my existing data purchases from DeLorme, collections on CD of USGS 7.5-minute quads by state, may be easily uploaded to the PN-20.

I'm not aware of any other handheld GPS that currently has the ability to show USGS maps, let alone aerial and satellite imagery. I find this an exciting development, in part because I usually use USGS sheets for backcountry navigation, and it's handy to have the same map on the GPS as I have in my hand! Most GPS units that display maps provide rather basic offerings, at additional cost. Whether I will find the aerial and satellite imagery useful for navigation is a question that I'll be examining over the course of the test, but it is (at the very least) a nifty and intriguing feature. I'll unquestionably find plenty of use the USGS quads (and the DeLorme Street and Topographic maps).

Various information fields may be displayed on the map page, according to the type of navigation that's being done. What's displayed may be chosen by the user. I'll discuss this aspect, and my experiences with uploading and using all types of maps, in the Field and Long Term reports. Based on my preliminary experience, I do have some minor concerns with the speed at which the screen is initially drawn (especially with high-resolution raster maps such as USGS). The speed at which it is redrawn when "panning" across a map is not especially fast either. Panning is not an especially crucial operation, but there are occasions (such as when creating a waypoint at a new location on the fly on the GPS screen) when the slow redraw speed may prove awkward. I'll be reporting more on this also.

The map's orientation can be altered using the menu key. So far, I have generally selected "North up," much as I would use a paper map. Other options are "Heading up," with the top of the map oriented in the direction of the current bearing, and "Course up," used when navigating a route, with the finish point always at the top of the screen. One other tool of interest, accessible through the Menu key, is the "Measure tool." This may be used to measure distances and areas on the GPS.

I have one significant area of concern, connected in part with the Map page. The direction of travel is indicated, as with most GPS units, by an arrow-like pointer displayed on the map. The PN-20 determines direction solely from GPS information. There is no built-in electronic compass, unlike the majority of GPS units I have used. This means that when I'm stationary, examining the map, if I turn to face a feature in the landscape, the pointer will not move, as my change in orientation can't be calculated from the received GPS satellite data. If I walk a short distance in the direction of the landscape object in which I'm interested, the GPS pointer reorients correctly.

This also means that if the GPS has been carried in a pocket (at least, when using my favored "North up" setting) the direction of travel indicator will not be correctly aligned with the landscape I'm moving through. It's certainly true that I can easily work around this limitation with a compass, which I'll be using in any case, but if (for example) I'm trying to identify a landscape feature just for fun, this lack of response is a nuisance. Still, electronic compass cards do have their own limitations, I've found. They need to be calibrated regularly, for one thing! Even so, the combination of bearing information from both the GPS satellite signals and the compass do generally make establishing orientation much easier. I'm a little surprised that this feature is not present in what's otherwise a unit of exceptional sophistication.

Other important menu items control which uploaded maps display, and in what order. These functions are found under "Map setup": the "Data Layering" and "Data management" tools. Suffice it to say for now that these are critical to the way that uploaded maps display.

Compass page
This shows a graphic resembling a traditional compass. How this works depends on whether I'm tracking (keeping record of my trip) or navigating (which DeLorme defines as following a previously programmed route). The same caveat I mentioned in the previous two paragraphs applies here.

Trip info page
This is a fully customizable page, whose data fields can easily be altered to suit whatever activity I'm engaged in. For example, on my ski trips, I was curious to know my maximum speed, a statistic that I've never measured. Therefore, I set the GPS (with the Menu button) to display those settings. I was rather surprised to see just how fast I was going on some of the downhills, though slightly disheartened at the fairly low average speed. Clearly I'll never be a cross-country citizen racer!

For hiking and backpacking, I'm able to set sunset/sunrise (and moonset/moonrise), useful for obvious reasons, especially for backpacks. The same screen can simultaneously show position (UTM/UPS or latitude/longitude), elevation, maximum elevation etc., etc. I've already used this page a lot. Resetting the data is easily accomplished through the Menu button, and it's possible to reset some fields without resetting them all.

Find page
This may (if enabled in Setup) be reached by cycling through the pages using the Page button, but it can most quickly be reached via the Find button. There are a variety of categories of information, and two find options: "Find Near Map Center" and "Find By Name." The first orders the list according to distance from the position indicated by the GPS. Available via Find are waypoints, points of interest, natural features, addresses, coordinates, cities, and streets/trails. This is a powerful tool. It's enabled by the type of base map loaded into the unit. Not all the listed categories are available for all basemaps. Options (as in most pages) are reached via the Menu button.

Waypoints Page
As with the Find page, this can be reached by "leafing through" using the Page button, but is most quickly available via the Make Waypoint button. A wide selection of waypoint symbols is available, and the waypoint can be labeled and commented (using the "virtual keyboard" which is accessible when the cursor is in certain fields). I have created a variety of waypoints, and have found the procedure straightforward and the results accurate. A rather nice feature is the "Average Waypoint" on-screen button which takes a succession of position fixes at intervals of about one second for additional accuracy. Another on-screen button creates a route to a given waypoint that can then be followed in the Map or Compass pages. Waypoints can be viewed using "Find Near Map Center" and "Find By Name." They can also be selectively deleted.

Routes page
This may be reached via the Setup key, or (if enabled in setup) by moving through pages via the Page key. I have not yet used this extensively, and will comment more in my future reports.

Tracks page
I have used this page frequently, and find it very straightforward. It is reached in the same manner as the Routes page. Generally, before creating a track, I use the Menu button to set the option that alters the recording interval settings. There are two types of interval, time and distance. I generally use time. Also programmable is the recording interval. The default is rather short (two feet or two seconds, as I recall), which may be useful for making a highly detailed map but seems overkill for recording the average trip. Also, since the track is limited to 10,000 points (position readings) it means that with such a low setting the track log (remaining capacity is shown by a percentage progression bar) will fill faster. With a two-second interval, the track log would fill in about 5.5 hours. By using a longer interval, tracking may be continued for a full day, or even several days, depending on the setting selected. Once a track is completed it may be saved (up to ten tracks may be stored on the machine) or discarded. If it is saved, the distance of the track is briefly displayed. Using the Follow (virtual) button converts the track to a route, which means that it can then be renavigated using the Route page. Saved tracks may be edited (for color etc.), hidden, viewed, converted to routes later, or discarded.

Tracks taken while the GPS has only a 2-D fix display in yellow on the screen. Tracks taken with a superior 3-D fix display in green. Any hiatus in GPS reception is indicated in red. So far, I have seen all green, no red!

Sun/moon page
This gives the moon's phase, moonrise/moonset, sunrise/sunset and the position of the sun and moon in relation to a compass. Not a major page, but a very handy one!

Tide page
This provides tide information, both at the time to which the GPS is set and at a future or past time. It does so for a number of tide stations, sorted by proximity to the GPS. As I kayak both on the Hudson River (which is tidal) and at sea, this is a feature I like very much indeed. I have not yet verified its accuracy, and will do so (both in practice and with a set of tide tables).

Device Setup page
This last page is key to correct operation of the GPS. From here, the system may be modified, by disabling the GPS, setting it to power saving mode, or using it in the default mode. WAAS may be turned off and on (since it consumes some additional power to have WAAS enabled, it's a good idea to disable it in an area where WAAS corrections can't be received). Battery type is also set from here. Display, interface, sound, page order, time and units are all controlled from this page. The Units sub-page bears special mention, as this is used to set coordinate type (latitude/longitude in various forms or UTM/UPS), the datum, whether the bearings shown are true or magnetic, whether ground measure is imperial, metric or nautical, etc. The range of available datums is impressive, although I did find the list scrolled jerkily with the up and down button. In changing from WGS84 to NAD27 (ConUS) I managed to miss, twice.

I've attempted to summarize the operation of the GPS in this section, but it must be understood that without (in effect) writing my own manual, with a tool so rich in features it's impossible to do more than just outline the wealth of available options. My main focus in the coming four months will be on how well they work.

GPS power use
I've found the strong backlighting of the GPS is sufficient to make the GPS easily read even in bright sunshine, but at higher brightness settings it depletes batteries quickly. The extent of battery use can, to some extent, be controlled. Probably the most effective method of doing so is to set the unit to "Power Saver" mode in the System screen of the Device Setup page. This sets the backlight to 10 percent intensity and sets the backlight time (the duration that the backlight is brightly on after a button press) to 15 seconds, the minimum period that may be specified. It does leave WAAS on, and as previously noted, this creates a small power drain, so this too may be turned off. If a trail is being created, setting the time (or distance) interval to a larger value may also cut down on power drain, although this will also reduce the accuracy of the trail, so this is a trade-off that needs some thought.

I have found that the lithium-ion rechargeable batteries are good for about one day of hiking, using a moderate backlight setting. I intend to experiment to find the best setting for longer (e.g. multi-day) trips. Of course, the easiest way to save power is to turn the GPS off and to take only occasional readings, which is my usual pattern of use. However, it is interesting and enjoyable to create a track during a hike and export it to the mapping program.

The GPS can be powered directly via the USB port (clearly, an option that useful in the field only if a small laptop is also carried). It will accept standard alkaline, lithium and NiMH cells, or the rechargeable lithium-ion battery pack that DeLorme cells as part of its Travel and Deluxe bundles. Whatever cell type is chosen, it needs to be specified in the "System" screen in order that the power meter to correctly estimate the rate of depletion.

My preference, for economy and performance, is the rechargeable lithium-ion battery pack. This is good, according to DeLorme, for between 300 and 500 uses (presumably complete charging cycles). It does, of course, entail a higher initial cost but to me this is a sensible choice for both economic and environmental reasons. (Even taking the minimum figure of 300 charges, one lithium-ion battery likely replaces 600 AA alkaline cells.) Recharging time for a completely depleted pack, using the AC adapter, seems to be approximately five hours, on average. Charging is complete when the yellow light on the charger goes out and is replaced by a green light. The pack may also be charged via the USB port of a computer, or in the GPS when correct to a USB port (rather like an IPod). I have not, as yet, compared the useful life of the various battery types in the field. I will try to give an idea of battery life during the balance of the test. Since there are so many variables, this will be, at best, a rough figure.

The manual suggests that batteries should be removed from the unit when it is in storage. To quote—"Because the Earthmate GPS PN-20 has a real-time clock which requires power even when the device is powered off, your batteries are constantly in use. If you use your Earthmate GPS PN-20 sporadically (e.g., more than a month between uses), it is suggested that you remove the batteries for long-term storage and then reinsert them when you want to use the device."

Preliminary field experience

While preparing the initial report, I used the PN-20 in a variety of settings, so I could familiarize myself with its operation. This included two cross-country skiing excursions. One of these was backcountry, in woods, fields and hills within a few miles of my house in the Catskills in New York State. The other ski trip (probably the last of the season for this area) was in the vicinity of the Mohonk Mountain House in the Shawangunks, on groomed carriageways. I've also used it while snowshoe bushwhacking Panther Mountain in the Catskills. On all of these occasions, the temperatures were quite mild, generally above freezing.

Elevations ranged to 3720 ft (1134 m). I compared elevation readings with USGS quads on the second and third trips. The high point on my ski trip is shown by the USGS topo for the area as within the 1260 ft (388 m) contour. The maximum elevation shown by the GPS was 1217 ft (371 m), a reasonable agreement. On the Panther Mountain excursion, the elevation at the summit was read as 3712 ft (1131 m), taken using the waypoint averaging feature, and this was an excellent match to the known highest contour of 3720 ft (1134 m). There's no USGS benchmark for that location, unfortunately.

On each of these trips, I logged a track, which I saved. My GPS was generally stored in a pocket, or in the top of my daypack, with no special care as to how the unit was positioned. The tracks appear to have no gaps: the GPS was able to maintain a location fix throughout. I also saved several waypoints, and found the procedure to create and label them very straightforward.

So far, the PN-20 seems to work equally well held vertically or horizontally. If there is a bias for one orientation over another I have yet to notice it. Most previous GPS units I have used work optimally only in one position or the other, depending on the antenna type within the unit. I am very impressed by the PN-20's ability to pull in satellites in just about any position. It seems that antenna technology must have improved a lot recently, to judge by this! I did not have to to resort to rotating the GPS in the direction of a cluster of satellites, or holding it overhead so my body doesn't block reception, commonplace maneuvres for most users of older GPS models.

In the months to come I will be using the GPS in a diverse range of settings, from deep backwoods to open water (I kayak, both sea and inland waters). I don't want to dwell on these preliminary experiences too much, as I'll be assessing the PN-20 carefully over time. These are simply some initial observations, and are subject to revision according to my field experiences.

I did check the DeLorme website for any updates to the firmware for the GPS, and downloaded the current version, about 14 MB. When I ran it, the update software reported that I indeed have the current version loaded. This attempted firmware upgrade went smoothly otherwise, and based on this experience I wouldn't anticipate problems in future.

Topo USA Version 6.0

The accompanying software is available optimized for use with the PN-20 GPS (it opens with a hint screen stating that this is the PN-20 edition of version 6.0). It is absolutely essential for uploading maps to the GPS and downloading data from the GPS to maps. It contains the Internet tools for the purchase of additional map imagery, and has a host of powerful functions. The interface will be reasonably familiar to users of some DeLorme software. This is a relatively powerful and complex program, not a simple utility.

It does have abundant onboard help. Not only are there many hints associated with actions (these can be turned off if they become annoying) but the help button, in addition to giving access to a standard Windows-style help system, also brings up an extensive manual in PDF format.

The program comes on two disks, one standard CD and the other, with the program data, on DVD. These are housed on a single spindle in a plastic case. After some teething pains due to both a defective program disk and an "iffy" data disk, I was finally (once a replacement program disk arrived) able to install. This proved quite straightforward. I had to call customer service for problems with the data disk as well. They had a workaround, and sent me a replacement for that also. The computer must be running Windows XP or 2000 with Service Pack 3 installed, 256 MB RAM is recommended (I have 1 GB), 700 MB of hard drive space must be available, along with a 3-D capable video card with 32 MB of VRAM. Previous versions of the software may be retained. The Earthmate Image Tagger program (for linking photos taken on a trip with the locations recorded by the GPS by reading the time tags on the images) was also installed.

A screenshot of a typical screen follows:

Screen shot

The program started, and opened a spectacular map of Mt. Washington, in the White Mountains of New Hampshire. While I love Mt. Washington, I was more interested in my immediate environs. I went to the tabs along the bottom of the map screen (visible in the image above) and selected "Find," the second from left. Using the "QuickSearch" form (there's an Advanced version that's much more powerful), I typed in "Olivebridge, NY." Above is the screen that opened, after I divided the view window. The left hand pane (which can be fully expanded, or completely closed) is a view of my typed location as shown on the appropriate USGS 7.5-minute quad. The right hand pane is Topo USA's view of the identical area. Note that, using the pull-down menu at top left, I could also have selected other types of available map imagery, satellite or aerial for example, assuming I had them available for the area in question.

At bottom right is a small map of the region, with a rectangle showing the section of map I'm viewing in the context of the surrounding area. If I want to examine an adjacent section of either map pane, I move the cursor to the edge of one of the frames, whereupon it turns into a hand icon, and I hold the left mouse button down and slide the map in the appropriate direction. I am also able to scroll the map using the directional arrow pad on the top of the right-hand vertical tool bar (see screenshots). Above that (directly under the Topo USA 6.0 logo) are the controls for scale, so I can zoom in or out on the map region. The increments range from 1 to 17, with intermediate zoom levels (e.g 11.4) available. 1 is, in essence, a view of the world. At 16 or 17, details are extremely magnified. Aerial data is borderline-useful at full magnification.

One interesting feature of the software is the ability to examine a map view in 3-D. The controls for this feature are also on one of the tabs along the bottom (although a 3-D view can also be opened by simply changing the small box next to the map type pull-down menu to 3-D). This creates a "bird's eye" view; the vantage etc. can be controlled from the 3-D tab.

The tabs at bottom (left to right, refer to image) allow access to map files; find (already mentioned); printing; provide a set of draw tools for various purposes such as creating exportable waypoints; control a GPS attached to the computer (this more for mobile laptop users); create a route for export to a GPS; create an elevation profile for a map feature or a draw feature; provide the 3-D controls; provide info on any map feature the cursor is on; operate NetLink, allowing the purchase of map data and the updating of the software; and Handheld Export.

This last tab (part of the functionality of this tab may also be reached by a button at the top of the screen) is central to use of the program with a GPS. This permits the uploading of various kinds of data, including map imagery, and the download of tracks, waypoints and routes. I have found it easy and fairly intuitive to operate. Below is a screenshot of a map with a downloaded track, from that first cross-country skiing trip.

Screen shot 2

The track is shown in red, with one waypoint where I saw the fisher (at bottom right). I didn't turn the GPS on until I was some distance from home, so the outbound track is slightly incomplete. This is a good demonstration of the high quality of track that may be generated with the PN-20. The map on which the track is displayed here is a USGS quad. Using the "Profile" tab I am able to click on the track, and learn that (among other things) I skiied 6.35 mi (10.2 km) with an elevation gain of 555 ft (169 m). Not exactly an epic adventure, but good to know the trip statistics!

The quality of Topo USA's basemap is very good indeed. I will be using these for navigation as well as my usual USGS paper quads during the test, for comparison. The contour interval changes as the map is zoomed in, down to a resolution of 20 ft (6 m), equivalent to the usual USGS quad interval. The maps show an extensive range of features, including woodland, roads, rivers, etc. Using the "Info" tab I can click on any given item and find out what it is. In addition, in the "Options" screen (reached from a button at the top of the screen, I can selectively hide particular features. Shading may be added to both the Topo and the USGS maps to better demonstrate relief, but I prefer to work without it, relying on reading the contours.

This is the merest summary of the workings of a sophisticated and ingenious program, which I will be reporting on further as the test proceeds. I am pleased with the ease at which data can be exchanged with the GPS, and maps uploaded. The installation issues seem to have been the result of a bad set of disks, rather than any defect in the program itself.

Aerial Data Packets

The procedure for purchasing these, from within Topo USA 6.0, using the NetLink tab, is fairly straightforward. I pressed the "Datasets" button with the map zoom set to 11 (this is the minimum for this process), selected about US $30 worth of imagery for my local area (satellite, aerial and USGS come bundled together), selected "add to list," then used DeLorme's purchase feature. The data is not instantly available, but I received an e-mail within five minutes (there's also notification on the NetLink tab) that my maps were ready for collection. The total file size for download was about 25 MB. I have a high-speed Internet connection, and that would seem to be well-nigh essential for downloading map imagery, given the file size of any significant amount of information. Download was extremely swift, and it seems DeLorme's servers are fast. It is possible to purchase ADPs in CD form and thereby avoid downloading, although not with the free certificate I was provided.

Once downloaded, I viewed the maps in the left-hand pane of Topo USA (I found that for some reason I had to restart the program first), confirmed that they were what I had ordered, and used the tools on the "Handheld Export" tab to save a map package of the aerial and satellite data (only, as I already had uploaded the USGS quads for my region). Processed for upload, the total was 47 MB, and as this was a fairly small chunk of data (though also a small chunk of terrain) I uploaded these to the PN-20 via the USB cable, which slots easily into the back of the unit. In the interim, I went on with this report. Transfer to the GPS from Topo USA via the USB cable is rather slow, and in future I will probably copy the files to the SD card directly. I used the "Options" tool to set the zoom range for this data to the maximum (N.B. zoom range for uploaded maps is controllable).

Having uploaded these to the GPS, I inspected them. The imagery was interesting, but the ability to zoom in was restricted by resolution issues. At the 0.5 mi (0.8 km) scale I had an interesting bird's eye view with the satellite imagery, at 0.25 mi (0.4 km) the quality was still borderline acceptable, but at 640 ft, 195 m (the next step) blurring was a nuisance. This is probably the highest zoom level that's likely to be of any conceivable field use, and indeed an "overzoomed" message shows at bottom left of the screen at this from the 0.25 (0.4 km) mile resolution on in.

If the DOQQ data layer is also enabled (using the GPS map setup, the layering options), when the satellite map data overzooms, the aerial map data displays instead, and this is of a substantially better resolution. The presentation, on the small TFT screen, is surprisingly adequate. While the ability to display this data is extremely exciting, I will be curious to see whether the satellite or aerial data is useful for field navigation. I do think it likely that the aerial data, at the least, may be useful for spotting potential camping areas and perhaps for avoiding heavily overgrown or rough terrain. Panning ahead of the location is a bit like getting a preview of the country ahead, although not enough to spoil the pleasure. I like the concept.


My initial impression of the Earthmate GPS PN-20 has been very favorable. While I have a few minor reservations above about the way certain features have been implemented (such as the lack of an internal compass and its effect on the ability to display accurate headings) these really don't detract significantly from the extraordinarily rich features of the device, not to mention the quality of the accompanying software. My hope is that these will prove to be minor matters, and I'll learn to work around them.

In circumstances in which I have been able to check accuracy, the PN-20 seems to be extremely accurate (certainly within the specified tolerances at the time the reading is taken) for position, and—based on my past use of altimeters—it is at least as accurate as a calibrated wrist altimeter for elevation readings. It's also capable of maintaining a good fix on location over a substantial period, making tracking a breeze.

The speed with which the TFT display for the unit redraws sometimes seems a little slow. Even when navigating lists of options, there seems to be a certain lack of responsiveness. This is not a major issue. A little more troublesome is the slow initial display of maps, especially USGS 7.5-minute sheets, and aerial and satellite data (Topo USA maps generally display much faster). While this is of some concern, it remains to be seen if in practice, over time, this proves to be an inconvenience. Still, the very fact that the PN-20 is capable of loading and displaying such complex imagery is a massive leap in handheld GPS technology, one for which I have been waiting for a long time. It wouldn't be an exaggeration to say that I see this as the harbinger of a new generation of GPS units with greatly enhanced capabilities.



I have intensively tested the PN-20 over the months of April and May. It has been operated in rain and shine, at temperatures from 30 F to 80 F (-1 C to 27 C) and at elevations to 4180 ft (1274 m). It saw use on half-a-dozen days of backpacking, a host of day hikes, a few walks, several drives, and a couple of geocache finds. All of this was within the Catskill Mountains of New York State, with the exception of one unsuccessful attempt at routefinding in Philadelphia, PA.


Testing history

Testing the PN-20 has been extremely interesting so far, although not always smooth sailing. The unit I was shipped at the beginning of this test worked well for six weeks, but shortly after the application of a firmware revision (firmware is the operating system of the GPS) I began to experience sporadic problems with USB connectivity when I attempted to upload and download maps, waypoints, etc.

In retrospect, I do not think those problems necessarily resulted from the firmware change, though I can't be certain. However, in discussing them with technical support, a secondary issue with my GPS unit was found (the unit's internal memory did not reformat correctly) and at the strong suggestion of the technician, I returned it and was issued a new one. This arrived about ten days ago, and occasioned no delay in testing as it was shipped before I had mailed the unit to be returned. I have had a few small issues with the new GPS (which is identical), including case pins (these are screws that secure the battery compartment, see Initial Report) that were too short. They were very quickly replaced by DeLorme, so I had a minimum amount of down time.

I remain, as I was at the beginning, very enthusiastic about the PN-20. Still, I do wonder (based on my experiences) whether DeLorme may be experiencing some minor quality control problems connected with the PN-20. Defective CDs, screws, and various electronic issues have certainly had some impact on my initial experiences with the device. On the other hand, DeLorme's technical support has been absolutely top notch throughout, to a degree quite unusual in this day and age. Phone queues have generally been short to moderate, technical support staff really know their stuff, and in addition there are online PN-20 forums on the DeLorme website (with both knowledgeable users and DeLorme staffers present) that have helped answer many questions. For all this I am very grateful. So far as I can tell (to some extent I am relying on my reading of the PN-20 forums when I state this), I am not getting special treatment as a reviewer, just the solid support that's available to all users.

I'll add that it seems to me that DeLorme is committed to correcting remaining software problems connected with the device and is dead-set on improving its functionality. In addition, they are slowly adding features requested by users. When I applied the most recent (1.2) firmware patch, a number of issues that I had hoped would be addressed had been dealt with, one sub-standard feature was removed (apparently temporarily), and display performance was improved. There were also several fine new features, one of which I had especially wanted.

It's my understanding that further firmware upgrades are in the works, and I look forward to these. While the PN-20 has been a useful GPS from the outset, it's nice to see that there is still a lot of fine tuning going on, which can only serve to further improve the device over time.

Upgrading the unit's firmware is very straightforward, and can be done either through the Topo USA 6.0 interface or by direct download from the DeLorme website. Something that should be emphasized is that all existing GPS settings are deleted during the firmware upgrade, and these must be re-entered, screen by screen. This is a little laborious, but I find this acceptable and it is probably unavoidable, based on what I've seen of firmware flashes for other products. I'd certainly suggest that anyone who has extensive custom settings that they won't easily remember should jot them down before running a firmware upgrade.

Mechanical issues

The PN-20 is externally a strong product. I have dropped it accidentally (lightly) a couple of times, and its rubber case certainly protects it well. As noted in the initial review, the buttons operate crisply, with audio feedback (a synthesized click). They are similarly good on the replacement unit. I haven't had any problems with the button layout, and in fact I like it very well indeed, now that I'm used to it. I find that I am able to
use the GPS in the dark, with no auxiliary light.

I do have a few minor concerns, based on my experience to date, regarding several aspects of the construction of the unit. These are not by any means of huge significance, but I do think they are worthy of mention.

Cable contacts.
The PN-20 is set up to accept both serial and USB computer cable connections. I have not used it in serial mode, just USB, and a serial cable is not supplied, but is available from DeLorme. The same contacts, a series of eight tiny brass plates, are used for both. These connect by direct contact with the projecting pins on the cable.

As noted earlier, I have had occasional problems obtaining a good USB connection from my computer to the GPS. The problems apparently coincided with a firmware upgrade, although I believe this was (most likely) coincidental. I cleaned the connections, at the suggestion of customer support, with isopropyl (rubbing) alcohol. This had no effect: the connection remained intermittent. However, on examining the GPS carefully with a lens, I saw a certain amount of tarnish to the contact plates. I purchased some fine crocus cloth, and gently rubbed down the contact area. This is a sufficiently mild abrasive that it does not noticeably scratch the plastic of the case, but it did quickly remove the tarnish, and I then had a consistent USB connection for the subsequent week.

After this, I returned this unit to DeLorme for replacement, as previously mentioned. However, I've since had a brief recurrence of the USB connectivity problem with the new GPS and a new cable. This time, I immediately cleaned the contacts with the crocus cloth, and my connection was promptly restored. I'm now almost certain that some form of tarnish or contamination of the contacts is the cause of the problem. This leads me to question the wisdom of having the GPS cable contacts exposed to the elements in this manner. How, for example, will the contacts fare if exposed to salt water? Based on these concerns, I'd very much like to see future versions of the GPS with a protective cover for the contacts, one that could be easily slipped off as required. Indeed, it may well be possible to retrofit this on existing units.

Battery compartment
The PN-20 uses a ribbon pull to help extract batteries. This is attached to one side of the battery compartment. It is really quite useful, especially with the supplied lithium ion battery, which is quite a tight fit. I have some concerns about the ribbon and its placement.

First, it is all too easy for it to get caught up in the Secure Digital card slot, which is hinged at its base. The ribbon must be held tightly off to one side when inserting or removing a card. If it were to catch under the slot (which could certainly happen unwittingly), and then be tugged, I fear it would almost certainly break the slot. I am not going to put this to the test, and I'm always extremely careful when working with this part of the mechanism! The slot (which is under the battery) seems to me in any case to be fragile, and I am concerned that it wouldn't take too much accidental force to cause substantial damage. I'd love to see the slot and hinge redesigned with greater strength.

Second, the tip of the ribbon easily (read: almost inevitably) catches under the waterproof gasket that provides waterproofing for the battery compartment and the SD card within. I cannot be certain yet to what extent (if any) this compromises the seal. I have not so far noted any moisture in the compartment, although I've not yet used the GPS in my kayak, where it would be most vulnerable. Still, anything that compromises the seal is clearly not a good thing.

For these reasons, I would very much like to see the ribbon replaced by an alternative solution for battery removal in future models, or (if it must be present) it should perhaps be run from the top of the battery compartment down, which would at least help keep it clear of the card mechanism.

The PN-20 in the field

Map types and display
Early on in the test, in addition to the free data download that is offered as part of the PN-20 package, I purchased a CD with the USGS quad, DOQQ (aerial) and satellite imagery for my region, since the portion of the Catskills that I was able to download with the supplied credits was comparatively negligible. I already have the quad imagery available in DeLorme Topoquads form (which is accepted by the GPS) but I was especially keen to own the aerial imagery, which I find fascinating. I'm left somewhat indifferent by the satellite imagery that's also included, as the resolution is poor. I ordered the CD using the "Datasets" feature on the NetLink tab in Topo USA 6.0, and I received it several days later. Unfortunately, for some reason a key file had been left off the CD, and I was unable to view the DOQQ imagery in consequence. DeLorme rapidly rectified this by enabling me to download the files online (at my request—they would certainly have shipped me a corrected CD). This was yet another occasion when I was appreciative of the firm's rapid response to problems.

I "cut" (DeLorme's terminology) a map of my region, incorporating three types of data—Topo USA 6.0, Quad and DOQQ—all of which I then loaded onto a 2 GB SD card. This gave me access to a vast array of map data, very impressive indeed. However, I quickly found (not, I should say, to great surprise) that while the DOQQ imagery is fascinating when viewed full-screen on the computer, it is navigationally useless on the PN-20. I simply could not, in the dense woods and mountains that cover this region, discern camping spots, trails, or other points of interest. I'm delighted to have the DOQQ data for research on the computer, but I have since removed it from the SD card. It's quite possible that in other settings (less wooded than mine) it would be useful for hiking and backpacking. I don't see much utility to the satellite imagery, except for large-scale overviews.

The interpretation of aerial and satellite data is, in any case, something of a fine art. On the PN-20, matters are not helped by the lack of any means to control screen contrast, which would be especially helpful with the black-and-white DOQQ imagery. The PN-20's screen is small, but the resolution and display quality are quite good, yet surprisingly the only screen control is backlight brightness. The colors on the USGS quads are a bit washed-out as well, although I have noted that if the screen is viewed at a slight angle color intensity is increased. I very much hope that contrast control, and perhaps other screen controls, are part of a future firmware upgrade. Realistically, I suspect that these are more likely to appear in a future premium model with a superior screen technology.

The speed of screen redraw is sometimes a little slow, though more noticeably so with USGS quads (which are raster imagery) than Topo 6.0 maps (which, I believe, are vector). It's rarely objectionably slow, in my opinion, and I seem to have observed a significant improvement in screen redraw speed since the firmware upgrade. I have also found that setting the map display with "North Up" minimizes the amount of redrawing. This is, in any case, my preferred method of map display on GPS units. The current version of the firmware did introduce a method that enables rapid toggling between two data types, e.g. USGS and Topo USA 6.0, a much-needed feature that I was delighted to find implemented.

Although I am not a geocache enthusiast, knowing that many GPS users do enjoy this hobby, I taught myself the rudiments, which are covered in the PN-20 manual. I downloaded two .loc files from a well-known geocaching site, loaded them into the "Draw" screen on Topo USA 6.0 (which accepts this format), then transferred the waypoints for the caches to the PN-20. It was, in all, a very straightforward procedure, covered in detail by the manual text. I also used the GPS to create road routes to the vicinity of the caches (more on routing later).

In both cases, I was able to locate the caches reasonably quickly, and the positional accuracy of the PN-20 was certainly up to the job. I did find the fact that the PN-20 provides accurate bearings on the map screen only when I'm moving (there's no electronic compass in the unit) a slight annoyance in the context of this type of usage. Having to keep moving to obtain and maintain a bearing is not ideal, especially when I'm close to the desired spot. This was also to prove a minor problem in field navigation. I experimented with creating direct routes from the road to the caches, but found that I prefer to simply use the map page to approach the cache waypoint.

Accuracy and navigation
Usually, the GPS obtains a satellite lock fast. I have found that reception is consistently best when the GPS is held horizontally, but that it is at least adequate, and often almost as good, when the unit is carried vertically. The lock, once obtained, is generally held, even under a fairly heavy leaf canopy. Occasionally, especially in areas ringed with mountains, when much of the horizon is blocked and fewer satellites are in line of sight, getting an initial lock is slower and less consistent, which is to be expected. It is in such settings that I have found the lack of an electronic compass to be a distinct disadvantage.

As an illustration, I have had one experience during which I was attempting to correct a map-reading error that had placed me off my intended trail by a short distance. I was hoping to bushwhack back simply by using the map page on the GPS and observing the position and orientations of the bearing indicator, but the lack of a reliable and consistent GPS bearing frustrated this attempt. I tried using my compass in conjunction with the GPS, but ultimately I ended up simply retracing my route, as I felt the wanderings of the GPS bearing indicator did not inspire confidence in position or bearing, and the terrain was unfamiliar. I do think an electronic compass setting would have helped correct the wide directional variations I was seeing.

The bearing pointer itself is overly large (it's a arrow-like isosceles triangle that displays in green when the unit has a good lock, yellow when it is marginal), and it lacks a clear indication of where (on the area covered by the pointer) the true position actually is. The geometrical center of the triangle appears to be the true location, but there is no dot or circle to indicate this, a commonplace indicator with many GPS units. I would like to suggest to DeLorme that they alter this symbol so it is clear that the current location is not (for example) the point of the "arrow."

When I first received the GPS, there was a great deal of "jitter" or noise evident in the data page. Even though I was stationary, just after booting the GPS the data page would sometimes show that I had been at 18,000 feet (5500 meters) moments before, and was moving at a substantial speed. To a significant extent, this was fixed by the recent firmware upgrade. I no longer see such random elevations displayed, though there is some (generally low) artificial horizontal movement shown, if I choose to display the speed fields. I don't find this a big deal, though I do believe that the remaining jitter is one factor in a certain unreliability that I've observed in my distance (odometer) readings, when I'm attempting to measure how far I have hiked. There has been improvement here also, and I hope for more with further firmware upgrades.

Elevation accuracy, when gauged on summits, has so far proved to be sound. In most instances, I have found (after ascending a summit with the unit on) that my elevation is close to that indicated by survey benchmark disks or USGS Quad contours. I find these results quite impressive (and more accurate than I had expected), and far better than my usual wrist altimeter results. Positional accuracy is generally very good as well, and is often more accurate than might be anticipated from the indicated tolerance provided by the GPS.

None the less, I have noticed that when going out and returning by the same path, my ascending and descending trails (when displayed on the PN-20 or in Topo USA 6.0) show significant variation, far wider than the path's treadway. In some instances, the positional difference may be as much as a hundred feet (30 meters). This isn't a terrible flaw (in my experience, this is not atypical among handheld GPS units), but it does lead me to wish that there was a port for an external antenna, as an antenna would probably improve the positional accuracy and might provide the necessary consistency for trail mapping.

The box for the PN-20 states that the device is able to "track against uploaded routes created on the desktop or calculate driving routes of its own within areas for which you have uploaded coverage." While I have no quarrel with the first part of this statement, I do find that routes generated by the PN-20 are, in many instances, suspect. I would also say (to be fair) that there has been improvement in the routing algorithms along with the firmware upgrade. No longer does a route over to one local peak traverse an ancient road that has long been state land, barred to all vehicles. I do hesitate to rely on a PN-20 generated route without examining it closely first. I usually have to make at least a few adjustments by adding waypoints to avoid closed roads, locally one in particular. (Here it appears that the base data, derived from DeLorme's Street Atlas program, is at fault, not the routing algorithm).

In order to route, both the Topo USA 6.0 map and the appropriate "Regional Map Package" must be uploaded to the GPS. These latter are listed in the Topo USA 6.0 "PN-20 Exchange Module," to be found on the "Handheld Export" tab. Route calculation is not that fast a process with the GPS, and if a deviation from route occurs (a wrong turn, closed road, whatever), a "back on track" calculation must usually be made. Often, in a moving car, such calculations may fail, as by the time the GPS completes its work the current location is off-route in another direction!

The bottom line? This is a clever feature, handy if I'm well and truly lost, but based on my very mixed experience I will not generally use PN-20 road routes unless I already know pretty much where I am going. This rather defeats the object of the exercise... In short, this is not that great a tool for auto navigation, except on a fairly rudimentary level. I should state here that I have never driven based on GPS directions to begin with, so this is not an issue of any great personal concern. In fact, I'm rather impressed that a handheld GPS can do as good a job as this one does, even with its limits.

In the first version of the firmware, there was a "simulate route" function, which would show the route and scroll the map from point A to point B. I found it clever, but too slow to display to be practical (partially a consequence of screen redraw speeds). This was removed in the current firmware version. If it returns, it will be interesting to see if it is faster.

Odds and ends
The PN-20 has a "Points of Interest" button. This displays the position of a variety of user-specified or pre-listed locations, and can route to them. I have used it mostly to locate specific peaks. The points listed vary according to the map database chosen. USGS seems fairly useless, but Topo USA 6.0 maps have a good set of P.O.I.s of all kinds. However, even when the peak name is provided (and "Mountain" is specified as the type of natural feature), when using my current location as the point from which to search, I've found that it can take ten minutes or more for the GPS to find a peak only 30 mi (48 km) from the house. This has been true with both the units I have used. This is a little disappointing.

I have also experienced one odd failure. I was recently using a 2 GB SD card with map data, when the GPS battery power ran out. The unit suddenly turned off (as expected), but it then started cyclically rebooting every few seconds, which was wholly unanticipated. I have subsequently reproduced this problem, which sometimes occurs when batteries are at very low charge levels. I had to remove the battery to stop this. When I put fresh batteries in and rebooted, I found that my SD card could no longer be read by the PN-20. In fact, it was so hopelessly corrupted that I have yet to be able to recover it by reformatting it under Windows or Linux, and it is probably a write-off.

DeLorme has kindly sent me another 1 GB card for further testing. Mine was a third-party SD card, and it is possible (as it was a fairly cheap brand) that it was in some way defective. (I was using it as DeLorme does not seem to have a 2 GB card available, as of this writing). I have ordered another 2 GB card, but this time a well-known brand. I have since tried to repeat the card problem with the original DeLorme 1 GB card. I have been able to obtain the "cycling" with batteries at very low power, but fortunately in this case without damage to the SD card (and most of the time, the unit gracefully shuts down at low battery levels). I am fairly confident that the damaged card was a one-time glitch.

The time that the GPS will run from a fully charged lithium ion rechargeable cell is hard to predict. There are too many variables, e.g. whether WAAS is on or off, the frequency with which the screen is viewed with the backlight on, the number of times the battery has been previously charged, etc. As a rule of thumb, I have found that, in general, the GPS will operate continuously for an eight to ten hour day hike. A couple of times, I have found that the unit is out of juice before then. If I use the GPS only as needed, rather than having it on continuously, I can use it for a three-day backpack and still have power to spare, though I was using the unit only to mark items of interest, not for navigation. As stated in the Initial Report, I don't navigate with GPS as my primary tool.

Lest this Field Report be read as a litany of woes, I want to emphasize that I am still delighted with the PN-20's ability to display USGS imagery, I'm generally pleased with its accuracy and features, I'm impressed with DeLorme's determination to improve the firmware, and that in fact I've become quite a fan of this GPS. No electronic unit of any kind performs perfectly, in my experience, and this does far better than most. It has already become my GPS of choice. I do not see returning to using my existing GPS, assuming that the PN-20 continues to perform as well as it has to date.

Topo USA Version 6.0

I have been very happy so far with the Topo USA 6.0 software, use of which seems very intuitive to me. I've had no significant crashes or mishaps. I downloaded Service Pack 2 (an upgrade) as soon as it became available, and this was applied without problems.

I do have a few reservations about the quality of the mapping. I base this on knowledge of my region. For example, I have found (without looking hard) at least three items labeled as navigable roads that in fact lie all or part on state lands in my area, where no motorized traffic is allowed. One of these "roads" in large part does not even exist, nor ever has (other than one short section at the base), but seems to be an arbitrary creation! Two that do exist are noted as "unimproved roads" rather than trails. These have limited significance overall as mapping errors, but their "road" status may potentially create an erroneous road route on the PN-20. One certainly did so, although with the new version of the PN-20 firmware this issue seems to have gone away. I have reported these issues to DeLorme via their website. There is a method for doing so within Topo 6.0, but I have had problems getting this to work, the only significant difficulty I have experienced with the program.

Among the tools available for dealing with tracks downloaded from the GPS to the software, I especially like the "Break line" tool. This enables me to separate one portion of a track from another, very handy when I have forgotten to turn the GPS off at the end of a trip. I can break the track once it is imported, and delete spurious portions. If necessary, I may then delete the existing track from the GPS and upload the corrected track.

My present opinion is that routing is best performed in Topo USA 6.0. The software allows the creation of Vias and Stops, points that help define a route, and these enable me to move the route defined by the algorithms in Topo USA 6.0 onto something of my own choosing. This is especially useful when there are known closed roads or other objections to the software-generated route.

I have made some use of the "Profile" feature, which (once a track is loaded from the GPS) allows me to calculate distance, elevation change, and a variety of other parameters. One tool that would be very helpful in conjunction with GPS tracks which is not (so far as I am aware) incorporated in Topo USA 6.0 would be a smoothing tool, something that would selectively average points along an imported track and remove those outlying points that are clearly the result of tracking error. Maybe something for the future?

I have found that the two program modules that control exporting and purchasing maps to the PN-20 both have some slight weakness. In the case of exported maps, I have not found a way to display an existing uploaded map and simply add sections to it that may be saved as a separate file. Instead, they get added onto the existing map, and that must then be uploaded again to the SD card. There are certainly many occasions when I would far prefer to create a separate file for the additions, rather than having to replace the file already on the card, the file size of which may already be quite large.

Similar limitations exist when creating composite groups of maps for purchase, as the grid system for ADP downloads is different for that for ADPs purchased on CD. In both cases, the tools for creating "mosaics" of maps for the PN-20, composed of smaller maps, are (unless I am overlooking something, which is always possible) either awkward or non-existent. This is not a dramatic deficiency, but proved a bit awkward when I was purchasing my Catskill imagery, and had to combine downloads with CD purchases to get the coverage I wanted. Blocks of map imagery purchased on CD are much more economical than those purchased for immediate download. I have used both methods in assembling my Catskill imagery.

One interesting ability of the software is to display and upload contours at ten-foot (3 meter) intervals. This, along with much else, may be set in the "Options" screen in "Handheld Export." I have not been able to find out what elevation model is used in the program, so it's unclear to me if these contours are created using real elevation data or if they are interpolated in some manner.

Topo USA 6.0 seems to be, based on my use so far, an indispensable tool for use in conjunction with the PN-20, and provides a necessary extension of the functionality of the GPS, in addition to a standalone program.

PN-20 Travel Pack

The various charging and power supply tools in the PN-20 travel pack have all seen frequent use over the past two months. I have had no problems with any of them to date. I especially like the plug-in USB port for charging, which connects to an outlet, and is handy with my MP3 player as well as the GPS! It's nice to be able to charge via a USB port without leaving a computer on for the purpose. The battery charger usually completes a charge in about five hours. The USB charger is somewhat slower than that, though I've not attempted to time it.


Despite a few teething pains experienced with the PN-20 during the Field Report period, I remain extremely impressed with the PN-20. I am pleased that the manufacturer seems dedicated to improving the operation of the unit, and I'm delighted with the level of technical service offered, which is head and shoulders above that for any electronic product I have purchased in recent years. While some functions could certainly stand improvement, taken as a whole this is an extremely powerful and efficient GPS, with some unique abilities, the most significant of which is (for me) the ability to display USGS imagery. I hope for trouble-free operation for the balance of the test.



I used the PN-20 on almost all of my trips during the two months of the long-term test. These included one three-night backpack over varied terrain in the southern Catskills; a two-night trip to Harris Lake in the Adirondacks (car-camping, as this was my base camp for a traverse of the Santanoni Range); and several overnight backpacks. These trips were in addition to numerous day hikes in the Catskill and Shawangunk Mountains of New York. Elevations have ranged from 500 to about 4440 feet (152 to 1353 metres). Daytime temperatures have ranged from about 50 F (10 C) to 85 F (29 C). In general, the weather was rather dry during this period, unusually so. I did encounter very occasional rain.


The PN-20 has performed trouble-free over the long-term test period. I have had no major repetition of the problems with the USB cable connection. On one occasion, the GPS helped me correct a navigational error that was potentially quite serious (and highly annoying). Although it's unlikely that I would have failed to catch and correct it by other means, I was very happy to have rapid confirmation of my mistake. I've also used it for a number of quite demanding bushwhacks, at those times when confirmation of my map and compass work was reassuring.

I am delighted to finally have a display that can show the 7.5 minute (1:24.000) USGS quads for the region, as I've found that I can generally glance at the display and then confirm my position visually on the computer-printed quad map (or maps) I have previously prepared in Topo USA 6, by simply comparing display and map. This means that I don't have to calculate my position using Northing and Easting from the UTM/UPS reading on the GPS, as I've had to do in the past. This is not a difficult technique, and it is more accurate than eyeballing my position in the manner I've just indicated, but for speedy confirmation of location a visual comparison is hard to beat. I have, in the past with other GPS units, found comparing proprietary map formats with USGS sheets awkward and potentially misleading, and have always used a calculated position when this was needed.

I have now developed a standard procedure that provides me with map coverage that's fast to display, yet offers a wide geographical range. No doubt other users of this GPS will develop their own favorite technique, but I offer this for what it is worth. I upload the USGS quads that I'm most likely to use on any given trip directly to the 75 MB of internal memory that the PN-20 includes. This is sufficient storage for (depending on the complexity) between three and five quads. As the standard USGS quad covers an area up to 64 square miles, depending upon latitude (i.e. 166 square kilometres), that's a lot of terrain. This seems (taking the uploaded maps as a whole) sufficient for just about any conceivable day-hike, and I have found it adequate for shorter backpack trips.

If necessary, DOQQ aerial imagery may be similarly loaded, but in general, as I have found this far less useful, I don't add it. There are rare occasions (one of which was on a recent hike) when certain terrain features (a canyon, in this case) show up better on DOQQ than on the USGS sheets, and this is where the photographic imagery comes into its own. I suspect that if I lived in real canyon country the DOQQ imagery would see much more use.

In addition to having fast-loading maps in the unit's memory, I have also loaded a large block of the surrounding region's quads (in my case, most of the Catskills) onto the SD digital card. These maps are slower to load and to pan, but they are there if I need them. I also have the Topo USA maps for the entire state loaded (also as one single file). These are quite fast to load from the card, and therefore don't need to go into internal memory. I have prepared similar SD cards for the Adirondacks and will do so for other regions. Before a hike, all I need to do is to insert the pertinent card, and cut and upload the appropriate maps to internal memory. If I forget or don't have time for the latter, I can always use the slightly slower-loading maps from the card. I find this a very effective system, though it does demand careful selection and ordering of the maps using the map management tools on the map page menu.

Though this does not qualify as hiking or backpacking use, I recently purchased a bike mount for the PN-20, and I have been using the GPS instead of a cycle computer on my touring bike. I am very pleased with the results so far. A screen-shot for a short trip is shown below. This is a workout route that I have done regularly over the years. The readings for average and maximum speed and for distance are in line with my expectations, based on previous records made with a bicycle computer, recently defunct. I intend to use the PN-20 for this purpose in future.

Bicycle readings

I have noted that on some hikes distance errors are introduced when (for whatever reason) the PN-20 fails to pick up a good signal for some distance while in tracking mode. Often, track points are created that are far off the actual position. There seems to be an error in the way that positions and distances are interpolated during periods of poor reception, or so I would guess. Since my last report, two months ago, no new firmware revision has been released, though one is rumored (on the DeLorme forums) to be imminent. My hope is that this problem, and perhaps a few other small glitches, will be corrected by this next firmware release.

I have successfully used the PN-20 to find an elusive trailhead while driving to a recent hike. The route selected was not, I later found, optimal, but it did the job. Based on my overall experience with road routing, I would certainly not consider the PN-20 to be ideal for car navigation (though the GPS is listed by DeLorme as suitable for this purpose), and indeed the small screen makes it perhaps potentially hazardous. As I've previously noted in the Field Report, the rather slow speed of route calculation also puts a limit on the utility of the routing function, especially when a "Back on route" must be performed while driving (due to a closed road or similar problem). Still, I'm glad that the GPS has this capability, for those occasions when I'm wandering on back roads.

Similarly, the "Find" function seems terribly slow, except for displaying existing waypoints, which indeed are promptly displayed. For me, this is not a significant issue, as I rarely use this tool on any GPS unit. So long as the waypoints display fast, I am happy. The fact remains, though, that using "Find" to locate (for example) geographical features is so slow at to be impractical, and this is a standard GPS feature that should not be deficient.

While I do have a few caveats of this kind, as I have remarked in the various stages of this report, overall I am pleased by the performance of the PN-20 as a GPS for backpacking and hiking. It meets almost all my criteria: excellent screen visibility in sunshine (even without backlight), fast satellite acquisition, good operation under forest canopies, etc. I still wish it had an internal compass, so that bearing changes would be updated when I'm stationary and examining the terrain. If there was one single change to the PN-20 I could suggest, it would be to add this functionality to the feature set.

Software, Data and the Travel Kit

Topo USA 6 has turned out to be a valuable addition to my small collection of mapping software. I've found it quite a powerful tool. While its integration with the PN-20 could be slightly improved (see my remarks in the Field Report) it is none the less an extremely capable program. One tool that I would like to see added to both the software and the PN-20 itself is some means of controlling the contrast of DOQQ data. For the software, something akin to a simple gamma control might do the job. There's a good deal of variation between the contrast of DOQQ images, and some end up displaying sufficiently dark that making out detail is tricky.

Overall, the quality of the USGS quads and the DOQQ imagery is high. There seems to be very slight fuzziness at certain resolutions of some (but not, by any means, all) quads displayed on the PN-20 that's not visible in Topo USA 6, although this tends to become less noticeable at higher resolutions. Comparing those quads I bought from DeLorme many years ago with the same recently downloaded indicates no improvement. This is a very minor issue, and it's possible that this is an artifact of the PN-20 rather than the scanned map.

The travel kit has performed reliably. Everything still works well, though I used up my supply of screen protectors (one went back with a returned GPS).


The DeLorme PN-20 has met or exceeded my expectations, which were fairly high from the outset. Despite some initial difficulties, which were handled with aplomb by the firm's technical assistance and customer service agents, at this point I am won over. That there is still room for improvement in the PN-20 is unquestionable, but the areas where it is most needed aren't generally those that have an impact on field navigation. The ability to display USGS maps (and to a lesser extent, the display of DOQQ and satellite information) is a very significant development, in my opinion. Battery life is at least adequate (though I usually bring a back-up set of cells on any long or multi-day trip if I intend to maintain a track). Speed in acquiring satellites has generally been on a par with GPS receivers using SIRF chipsets (based on my observations of the GPS units of others on hikes). Positional accuracy is generally very good indeed. Even elevation readings seem surprisingly accurate. The limitations that I have mentioned previously in the road routing and "Find" features I do not (personally) consider critical to field use of the GPS, and it's quite possible that performance in these areas may be improved by future firmware changes.

The accompanying Topo USA 6.0 software is stable, powerful, and full-featured. While there is some possible room for improvement in the Map Exchange module, there is nothing there resembling a really substantive shortcoming. It's an excellent program, and I find it very intuitive.


I intend to continue to use the DeLorme PN-20 GPS, along with the Topo USA 6 software, data, and all the peripherals for the foreseeable future, or at the very least until the next big step forward in GPS technology occurs, whenever that may be. The availability of USGS imagery on the PN-20 is the deciding factor in this decision, as this was something I had long wanted to see. Kudos to DeLorme for being the first to meet this need.

This concludes my report series on the DeLorme PN-20 GPS. I sincerely thank DeLorme and Backpackgeartest for the great opportunity to test this GPS.

This report was created with the Report Writer Version 1. Copyright 2007. All rights reserved.

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