twolpert

Second day in a row. It's for some kind of server-side upgrade. In all fairness, it is unusual. On the other hand, they choose to do it during prime time for their US audience... Pretty sure you'll get the same answer over there -- at least from me In all seriousness, some of the folks who post over there regularly also frequent this board. Somebody else may well chip in here as well.

Haha, I tried to stay out of it too but couldn't resist. They're really such different units, aimed for different market segments and price points. Toyota vs Mercedes comparisons (for someone trading up from an old Ford Escort) kept coming to mind. Shopping advice, not opinions on the merits of the units. No way I'm goin' there

It's actually more complicated than that. And it depends on your network provider. If you're really interested, there's much more detailed information available here: http://arstechnica.com/gadgets/news/2009/01/assisted-gps.ars

The "blip" is a fairly common artifact of multi-path errors with a high sensitivity receiver. As the unit switches among the various reflected signals from the same satellite, the position calculation will occasionally yield wildly different reported positions from one sample to the next. Usually, the differences are more on the order of 40 or 50 feet, but larger variations are possible. When this happens, the unit may record a very high speed for that "leg" of the track (since it thinks you went a long way in a short time), as well as adding the erroneous difference to the distance traveled... Trying to smooth out these artifacts is what leads to errors in the distance travelled. If you smooth too much, the distance comes out shorter than it should be. If you don't smooth enough, these "blips" cause the distance travelled to be too large.

Aaagh. No way I'm jumping on this one again If you have an REI in your neighborhood, suggest you head over there (preferably during a time when they are not hugely crowded). You will be able to examine both units, probably even taking them outside for comparison. You can read about the features, read the reviews, etc. -- but there's no substitute for holding them side by side. One other note -- you're probably paying something of a premium for the camera on the 550t. If you're comparing on price, might want to consider stepping down a bit on the OR -- say to the 400t. The feature sets, particularly with regard to the inclusion of 1:100K topos, will be more nearly comparable that way.

I have one and I love it. But I rarely travel outside the US, so the DeLorme blinders are not an issue for me. But these things are issues for lots of people. Other problems include the lack of maps/imagery for areas outside the US (or, at least, outside North America); lack of support for grids other than lat/lon and UTM; lack of support for user-defined grids. Depending on where you are located, I suspect those might be more substantive for you than lack of support for your time zone

Would like to see comparison of behavior in challenging (multi-path) conditions. How "stable" is the reported position in the neighborhood of GZ? That is, how consistent (and how correct) is the "pointer" in this environment? Since not all units have electronic compasses, I guess this has to be done with compass off to level the playing field. In a more general sense, how "noisy" is the recorded track in multi-path conditions? Comparison of workflow for loading a PQ? Comparison of workflow in the field, especially for somewhat unusual operations like changing the location of the cache for stages of a multi, viewing the cache description when navigating (both to the cache and to an arbitrary waypoint in those cases where I cannot change the cache location), and so forth? Ability to easily and accurately project a waypoint? Ease of using different distance units and magnetic/true for the projection? Comparison of carrying convenience? Does any unit have an antenna orientation bias to the point of interfering with typical (lanyard, pocket, belt loop) means of carrying the unit? Thanks for doing this. I have my own comparisons for PN-40 and CO, but no experience with OR or Lowrance.

Pretty sure that what you see (in the TimeZones drop-down accessible from Menu->Device Setup->Time) is what you get. Suspect that any shortcomings in the list of available time zones are a result of DeLorme's narrow focus on the US...

I'm with StarBrand on this one. It's going to vary from model to model -- and some models are consistently better or worse than others. Getting this part "right" in the firmware is a difficult balancing act, especially with high-sensitivity receivers. On the one hand, you want accurate moving/stopped times and accurate distances. On the other hand, you're trying to smooth out spurious "motion" that's due to multi-path effects -- effects that are much worse with high-sensitivity receivers. Pretty sure it's a no-win for the poor programmer

I can report that the Google maps mashup works on 32-bit Vista and 32-bit XP SP3 with IE8. No problems. Everything in both environments is fully patched. And I avoid IE add-ins (like toolbars) like the plague. The first thing to check is probably to see what toolbars, third-party pop-up blockers, etc. you have installed. Edited because I can't type.

There's a registry hack for this. It's been discussed on the DeLorme forums, but I can't find the reference. Thoroughly unsupported in any case.

You'd have to lose GSAK if you want to go Mac-only. There is a developer version of GPSBabel that supports the PN-40 directly on both Windows and the Mac. However, without GSAK on top, you might as well just use the DeLorme Cache Register as dakboy suggests. If you do run TopoUSA in a virtual machine on the Mac, there should be other ways to get the cut maps onto the PN-40 (other than via Topo itself). Although I'm not a Mac user, it seems like you ought to be able to take the SD card out of the PN-40 and use a reader to transfer the files to the SD card. Hopefully, the virtual machine would support standard removable disk USB devices. I know there are Mac users of the PN-40 who post fairly regularly on the DeLorme forums. If none of them show up over here, you might want to post over there instead.

I'll say it one more time. If you're out in the back country with nothing but your GPSr, you're a rescue waiting to happen At a minimum, you need backup maps, a compass, and enough knowledge to use them effectively. It's not necessary to know your exact position at all times nor is it necessary to have a complete plot of your route on the map. But it is necessary to know approximately where you are, which way you need to go to get out, and the gross terrain features that will help you find your way out.

This is a graphic illustration of what Fegan said above. Also supports my observation that the error in distance and direction is random. To elaborate a little, there are two sources of error involved in finding GZ. First, there was some error in the coordinates when the cache owner placed the cache. This is probably between 0 and 15 feet or so, but might be larger. Second, when you go looking for the cache, there is an entirely independent error in your reported position -- which is also in the 0 to 15 foot range most of the time. If the two error values happen to be large and in opposite directions, you could end up 30 feet or more from the cache. If both errors are small, or if they happen to be (and it would be entirely coincidence) about the same size and in about the same direction, you will end up on top of the cache. This is why most cachers stop looking at the GPSr and start looking at the environment when they get within 30 feet or so of GZ

The waypoint marks the same location regardless of the datum (WGS84, NAD27 CONUS, ...) or grid system (lat/lon, UTM, ...) you use to display the coordinates. The unit stores the coordinates in WGS84 internally and converts them for display. Put simply, you will always be able to navigate back to the waypoint no matter how the coordinates are displayed. There are only two situations in which the datum and coordinate system matter: a) When you use the information with a paper map. In that case, you need to display the coordinates in the datum and grid system used on the map. When you enter the coordinates manually (rather than by marking a waypoint). In this situation, it is vital that the unit be set for the datum and grid in which the coordinates are expressed. By extension, this means that you need to pay attention when giving coordinates to somebody else. For example, when posting geocache coordinates, they are always given in WGS84 lat/lon (degrees and decimal minutes).

No, there is no way to be selective other than by adjusting the query parameters. The two best ways to limit the number of caches you retrieve are (a) limit the number (near the top of the page, look for "Show me xxx caches") or ( limit the search radius (about half way down the page, look for "Within a radius of xxx" mi or km). To get a feel for what you're getting, do not schedule the query to run when you initially set it up. Instead, return to the page that lists your PQs. Then use one of the two preview icons (in the column headed Preview) to preview either as a list or in Google maps. I like the Google maps preview myself. THEN, if you want to download individual caches, you can use Send To GPS to get individual ones (assuming your GPS supports it). Note that using "Download Waypoints" from the preview list page will give you .loc files, not .gpx. The .loc has coordinates but not much else. To get full details, you need to use Send to GPS or go to the cache page and download as .gpx. Hope that helps.

This kind of consistent error smacks of a datum issue. If other cachers report the same consistent error, it is likely that the owner is using a datum other than WGS84. Almost any other source of error, such as multi-path effects, differences in the constellation (DOP and the resulting uncertainty in reported position) is going to be randomly distributed in both direction and distance across multiple caches.

Yeah, it was more in the nature of a bump and a little clarification than anything else. Maybe an Oregon owner will chime in here...

Colorado 400t or Oregon 400t? Can't give detailed instructions without knowing. 1) This is an option from the map page. On the CO, push the Options button, select Change Data Fields, highlight the field you want to change using the wheel, click Enter (center button on the wheel), scroll to the new data item using the wheel, press Enter again. Operation on the OR will be logically similar but I don't know details. This assumes you are not in geocaching mode. I am pretty sure that bearing (pointer) and distance to next are shown on the CO (at least) on the combined map/cache header screen when navigating to a cache. 2) Not possible on CO. Don't know about the OR. 3) I am not sure what this question means. If you are routing to the cache (on either unit), the routing line on the map connects your current location to the cache location. If you are zoomed far enough out, you will always be able to see both your current location and the cache. If not, you will need to pan the map to see the cache location. On the CO, you do this with the four-way rocker on the wheel. The OR will have a gesture to do the same thing.

Your unit will do this for you. The only thing you need to keep in mind is that if you enter coordinates manually (as opposed to marking a waypoint), you must first set the unit to the datum of the coordinates you have. I assume you are working with a waypoint you marked. All you need to do is set the unit to WGS84. The coordinates displayed will now be in that datum. Now let's suppose you want to manually enter the coordinates of a cache you saw on geocaching.com. FIRST set the unit to WGS84. Now enter the coordinates manually. If you want to see the coordinates in NAD27 for Alaska (for example, if you want to use them with a paper map which uses that datum), switch the unit to NAD27 for Alaska. The coordinates will now be displayed in that datum. That's all there is to it. I am unclear about your question regarding format. It appears to me that your unit is already set to match gc.com. There are three common formats: Decimal degrees. (Whole degrees and decimal fraction of a degree). Decimal minutes. (Whole degrees, whole minutes and decimal fraction of a minute) Decimal seconds. (Whole degrees, whole minutes, whole seconds and decimal fraction of a second) Geocaching uses decimal minutes. ddd mm.fff

As you suggest, you really need to try the units in the field. Comparing EPE numbers across different models, let alone across manufacturers, is not meaningful. None of the manufacturers disclose their EPE formulas. All of them are probabilities, and even the choice of probability confidence level makes a significant difference in the reported EPE. For example, CEP (one of the more widely cited formulas) offers a 50% probability that your reported position is within EPE feet of your actual position. To raise that probability to 95%, you would have to approximately double the EPE. This is why EPE on a single unit should be treated as a relative figure of merit ("smaller is better"), rather than a guarantee of accuracy. And why comparisons across different manufacturers/models is meaningless. What counts is repeatability on the ground.

Possible, but I think you'd have to be holding them very close together (like in one hand). It's not the GPS-ness, it's electric or magentic field interference. To give you an idea, a big part of the reason you should recalibrate the compass each time you change batteries is that differences in the fields generated by the current flow through the batteries affect the compass.

The problem with "jumping around while walking" may be affected by the speed with which you walk. While you are standing still or moving slowly, the Oregon (like virtually all units with an electronic compass) uses the compass to determine direction of travel (or the direction you are facing when standing still). At higher speeds, the unit uses satellite information to determine direction of travel. If you just happen to walk very near the cutover speed, the unit may switch back and forth between the two. However, in order for variation to be apparent, either the compass has to be out of calibration, you have to be holding the unit at an angle (rather than straight in front of you), or something in the environment (like that WWF belt buckle) is affecting the compass.

I own a DeLorme PN-40, which has better road routing than the PN-20. I don't think anybody would really recommend the PN-20 for road use, since road routing was notoriously slow. I have used the PN-40 for occasional road routing. The plus side is that the routable maps come with the unit -- no extra charge. The down side is that you get what you pay for The concensus seems to be that the map data and routing algorithms are not as good as Garmin City Navigator (which, of course, costs extra). It still routes fairly slowly and tends to have difficulty re-routing if you stray. As with all handhelds, it lacks spoken directions and is not exactly easy to see on the dash due due display size (brightness and contrast is fine). Presumably that's not an issue for you since you've been using a handheld. My take is that it's OK for occasional use, but definitely not competition for an automotive unit. Hopefully, some of the folks who can compare it directly with the PN-20 (and who have more road routing experience than I) will chip in with more information.

Colorado and Oregon paperless features are very similar. If price is an issue, it may be easier to find sale prices on the Colorado, which is a somewhat older line. However, the RockNRoller (wheel input device) on the Colorado is an acquired taste.