When it comes to handheld GPS units, Delorme already had a winner in the Earthmate PN-20. With near instantaneous satellite acquisition using a 12-channel STMicroelectronics GPS chipset and 75 MB of onboard memory, it held its own among the competition.
Delorme did not wait for someone to design a unit to outperform the PN-20. They designed the PN-40 to leave their own designs in the dust. The PN-40 is equipped with a 32-channel chipset that locks onto satellites in less than 60 seconds from the time it's powered on. It is capable of acquiring a 3-D lock in half the time of the PN-20.
A dual-core processor has been included to achieve rapid screen redraws. Displaying color aerial imagery on the screen is the most useful feature we have found on any GPS. With the PN-20, a screen refresh of such imagery took a couple seconds. With the PN-40, a changed view occurs as a flash on the screen.
The PN-40's onboard memory holds 500 MB of imagery, tracks, routes, and waypoints. If that's not enough space to get a job done, it accepts SD cards with up to 32 GB of storage. We loaded 14 square miles of color imagery onto the PN-40. That load occupied 52 MB of storage space. Using that experience model, it would theoretically be possible to store 10,000 square miles of aerial imagery on one 32GB SD card.
Aerial imagery is the most powerful tool available when trying to locate anything from a geocache to a faint trail in the woods. For example, if you are walking beside a creek, when you look at the screen, you can see yourself walking and you can see the creek beside you. While driving or walking through a neighborhood, you can see each individual house on the screen as you go past it. Basically, the picture you are looking at on the GPS unit is the same image you would see if you brought it up on GoogleMaps.com. The advantage is seeing your own position on that map.
The PN-40 is shipped with a copy of TopoUSA 7.0 with topographic maps for the entire country. The software is licensed to be installed on one desktop computer and one portable unit such as a laptop. Everything uploaded to the PN-40 or downloaded from the PN-40 is done through TopoUSA 7.0. For a subscription price less than $30, you can get unlimited downloads from the DeLorme server which includes a variety of satellite and aerial packages throughout the United States that overlay the preloaded maps.
If sharing trails and routes with friends is part of your routine, the PN-40 package is all you need. Everything you do on the PN-40 is stored in files that can be downloaded to TopoUSA and emailed to anyone you know. For example, email your track for a favorite campsite to a friend. They can upload it to their PN-40. Your route will display on the PN-40 and your friend can follow it step-by-step to your campfire.
The author monitors his progress...
The author monitors his progress as he walks in the open space park.
Before leaving for the hike,...
Before leaving for the hike, I used TopoUSA 7.0 to load color aerial imagery to the PN-40. The screen displays the area in full color. Even the trees are visible. The arrow shows our current position and direction. The yellow line is the track we used. In this case, it shows we left the main trail and are walking through the woods.
Another screen on the PN-40...
Another screen on the PN-40 gives us the information about our hike. The chart can be customized to display different information depending on user preference. We like to look at current position, distance and time traveled, average speed, and a few others.