DeLorme PN40 observations

[doc_kreipke]

A couple of personal observations after a few hiking trips with the PN40:

As far as downloadable imagery goes, I pretty much use the aerial photographs exclusively. The USGS colored topographical maps look great on my computer, but I'm not impressed with the resolution on the PN40's screen. The Topo7 maps that come with the unit are as good as the USGS maps, in my opinion. As far as that goes, if I'm just out hiking about and using the PN40 to ensure that I don't get lost, I don't even need the aerial photgraphs; the Topo7 stuff serves me just fine.

While the PN40 itself is of robust construction, the SD card seems to be kind of sensitive to blunt trauma. One time, I dropped the unit. Fortunately, I had it attached to my wrist with the carrying cord, and it didn't hit the ground. It did arc down pendulum-style and boinked against my car fender; not a hard hit at all. Subsequently, though, it started acting quirky -- it wouldn't display the topo map, and it would re-boot itself whenever I asked it to display the waypoints screen. To make a long story short, I finally fixed it simply by popping the SD card and firmly re-inserting it. So, if your unit suddenly acts as if it has been possessed by poltergeist, the SD card may have been jostled loose.

[Siskiyou]

When you viewing the image can you scowl over a couple of drainages and zoom in on it.  How close is the detail?

Good tip on the SD card.

[doc_kreipke]

While viewing a map, you can indeed scroll around on the screen by using the arrow button that you use to move around in the menus. You can zoom in and out while you're scrolling around, too. You scroll around on the screen by moving a little diagonal arrow (like a computer mouse arrow). Whenever you position the arrow on a geographical structure (e.g. road, lake), the screen tells you what it is in the lower left corner.

In the lower right of the map screen, there's an interval bar showing the scale. It ranges from 10 feet to 500 miles. You get an outline of the United States on the 500 mile scale. The interval bar is about one fifth of the screen width.

With the aerial photo imagery, you can easily recognize types of terrain (forest, clearing, water, urban strips, etc) at 0.25 mile & 640 ft. scales. At 320 ft, you can discern individual buildings. The display starts to get blurry at 160 feet per interval. At 40 feet, the display is an indecipherable mosaic of big colored pixels.

You can hybridize the aerial maps to superimpose the Topo7 roads & contour lines onto the aerial display. (While viewing a map, push the MENU button > scroll down to Map Setup > Enter button for the map setup menu > scroll down to Show Hybrid Map > Check the box with the Enter button > back out to the map view by pushing the QUIT button until you get there.) These don't show up until the 640 foot scale. At the 320 foot scale, even more contour lines show up.

The Topo7 maps below the 0.25 mile scale start dropping important details (e.g. bodies of water! -- blub, blub if you're not paying attention). Roads and contour elevations do remain on the map, however. Everything disappears at the 20 foot scale.

I don't have any actual hiking experience with the USGS topographical or maritime maps. I would guess that since they're "imagery", they would behave in a similar fashion to the aerial photos. Maybe someone else has and will chime in.

When using the PN40, I usually operate at the 640 or 320 foot scale with the aerial photos, and 0.25 mile scale with the Topo7 maps.

As always, the above are my personal observations, and YMMV.

[Siskiyou]

Very nice, thank-you.