dogwalkers2

Garmin's FAQ page on their website (search for accuracy circle) says the following:

I haven't yet looked at the other replies, but here is my $0.02 worth (Canadian, btw) Is the primary difference between the Vista and the Legend the electronic compass and the barometer? (Anything else?) -Yes How much more useful is the electronic compass than just moving a few meters to get your heading on one without it? (Is it worth the extra money?) -I think it's worth it. If you are navigating other than just geocaching, it also incorporates the ability to sight an object and project a waypoint to that object, either based on a default distance (so you get a track line) or by estimating the distance. I can't see myself needing the barometer, but if I have it I may use it - any comments? -I find it useful, but not as much as the compass I see the Legend HCx on sale at Walmart right now for $269.97 (in Canada, btw) - is this a decent price? Is the advantages of the Vista really worth the extra money? -Not a bad price for instant gratification. GPSCentral.ca has it for $239 plus $15-25 shipping, depending on how fast you want it, plus the bonus of no PST (they're in Calgary). Prairie Geomatics has it for $249 plus $14 shipping outside Manitoba, but you have to pay PST. Do these models come with the PC interface cable, or is it usually sold seperately? (I see they are somewhat expensive to buy seperately) -They come with a USB cable Both of these models don't come with the SD Card - how much is an SD card, and is there any internal memory on these models? (Eg: can I download any maps without the card?) -You need a microSD card to load maps. If you are using TopoCanada only, you should be able to get away with a 1GB card, since you'll reach the 2025 map segment limit before then. However, a 2GB card (the max size it will take) is at the memory "sweet spot" for price. If you have a computer parts dealer nearby, you should be able to get a 1GB card for $30 or a 2GB one for $40. Best Buy is close to twice this price. Walmart may be OK. If I return this bundle I lose the topo software... however it's already installed on my PC - will it work with a new GPS, or will I have to buy it again seperately? -Legally and ethically, you need to buy it again. You'll also have the discs if you change computers. Any other makes or models I should consider? I have looked at the GPSMap 60 series as well, though I can't really see any advantage of them over these models, and physically, I like the eTrex series better. -My understanding is that form factor is the main difference. Functionality is pretty much the same. However, I have never used a 60. Anything else I should be aware of, or am posibly overlooking? -Ensure you get the HCx of whichever version, as opposed to the Cx. The price is the same with the added benefit of the high-sensitivity receiver. GPSCentral sells both. Prairie Geomatics considers the Cx discontinued and no longer carries it. Also, in the real world, how useful is the Hunt/Fish calendar on these? What exactly is the Geocaching mode? (the basic Legend I have doesn't have this) -The Hunt/Fish calendar is on all the Garmin GPS, I believe. I don't know what it bases it on (phase of moon?) but it just lets you know whether it is an average or good day and what times are the best. I don't hunt, but when is it not a good time to fish? Geocaching mode simply allows you to identify unfound geocaches easily and to easily mark them as found and record the finding in the calendar. As far as the odometer "bug" goes, I don't find it to be a show-stopper. For example, the blue Legend would not register distance travelled when it did not have a signal, so its odometer was most often wrong as well. IF you are interested in the distance travelled after the fact, it can be retrieved from your track log on MapSource. If you must have the accurate distance in real time, then I gues it would be a problem.

With the map setup page showing, bring up the menu with the "find" button (lower left). There will be an option to hide the map product (i.e. metroguide, city nav). You may have to be on the part where you can turn off individual maps, but I'm not too sure and I don't have my GPS handy right now. Same process to show it. This is far more convenient than swapping cards.

Try Main Menu>Setup>System, Click the "Find" button (lower left) and there is an option to "Restore Defaults" I don't know whether that is all factory defaults or just the ones from the system setup page and I really don't want to change mine. Or you could try the three finger start. Hold down the page key (top right) and the click stick while starting the unit. This should reset the unit (it will probably ask you if you are sure). See http://gpsinformation.org/dale/secret.htm Again, I don't want to try on my unit to make sure. Good luck...

Oh, and before getting into the why bother with pressure altimeter comments, the pressure altimeter (in autocalibrate) smooths the transitions caused by the short-term GPS jumping, while the GPS altitude keeps the longer term accuracy, without manual recalibration. Also, if you did not calibrate your altitude when you turned on your unit, it starts off on its last known calibration and takes awhile to autocalibrate (part of the smoothing routine). If the atmospheric pressure has changed quite a bit since you last turned it off, it will be out by more initially and take longer to get close than if the pressure is the same or similar. I get it. The altimeter is dysfunctional by limitations of barometric pressure changes. I need to know the altitude or barometric pressure, from some other source, and recalibrate at least every hour, so that the Vista HCx will tell me the altitude to +/-150 feet. But it's "not a bug." Really, I'm not against this GPSr. It's way beyond anything that's available in the current $219 price point. Unfortunately the speed under 2 mph is likely to have equally distasteful limitations. Actually, if you do what you mention, the accuracy is +/- 10 feet. If you leave it in autocalibrate, its accuracy is +/- 50-125 feet. This accuracy is based on the nature of the entire system (satellites, frequency, C/A code, ground monitoring stations, etc.), not just the particular GPS receiver you have. With respect ot barometric altimetry, that's the nature of the beast. Aircraft rely on barometric altimeters and if they are flying below transition level/altitude (18000 feet in most of Canada and all of the US) they must adjust their altimeter on a regular basis. More often than hourly is not uncommon. I have been on approach and within 15 minutes, have changed my altimeter setting more than five times, just because of rapidly changing weather patterns. So, no, it's "not a bug." What would be a bug is if you correctly calibrated it and it read more than 50-75 feet out (that's the tolerance of an aircraft pressure altimeter, why should a consumer grade GPS be better?).

Under Main Menu->Setup>Altimeter be sure that you have selected Variable Elevation under Barometer Mode. I have the settings just as you described. Fooling around with this unit, while sitting at my desk in the last 30 minutes, I have, according to my altimeter, sunk through the slab foundation and am now typing 70 feet below my house. Oh, now i'm beginning to surface now. It's really interesting, but i would swear I haven't left my chair. Not a bug. Here's what Garmin has to say about it: Oh, and before getting into the why bother with pressure altimeter comments, the pressure altimeter (in autocalibrate) smooths the transitions caused by the short-term GPS jumping, while the GPS altitude keeps the longer term accuracy, without manual recalibration. Also, if you did not calibrate your altitude when you turned on your unit, it starts off on its last known calibration and takes awhile to autocalibrate (part of the smoothing routine). If the atmospheric pressure has changed quite a bit since you last turned it off, it will be out by more initially and take longer to get close than if the pressure is the same or similar. Back to the original thread (2 units): 1 - Approx. Date Of Purchase? Aug 07, Nov 07 2 - Purchase Location? Prairie Geomatics X2 3 - Unit Software Version? * 2.40, 2.40 4 - GPS SW Version? * 2.30, 2.40 5 - Unit ID? * yes to both 6 - Have you updated the firmware yourself? yes on the first 7 - Have you noticed the Trip Computer bug firsthand? ** yes on the first (you have to be walking really, really slow, I had a hard time going that slow), haven't tried on the second 8 - Does your typical usage depend on the Trip Computer function? no, no 9 - Have you contacted Garmin about the issue? no, no

1. I use NT..you can get by with a 1GB card. Or, if you have a 2GB card, then you have tons of room for either custom POIs or axtra maps like topos. I have about 1.5GB full with both CN NT for all of North America and topos covering from the Man/Sask border to the east coast, within a couple of hundred miles of the TC highway. 2. My understanding is that since the CN unlock is tied to the GPS, you can load it on as many PCs as you want, but can only link it to one GPS, so it should be no problem loading it on your computer and then hers at home. When installing on your computer, I wouldn't upgrade, if that is an option, since that might somehow tie it to your GPS. I don't know for sure....

This is why it needs to be calibrated regularly (or set to auto calibration - in the case of a Garmin; I don't know if Magellans have the autocalibration feature). As was mentioned in another thread, the barometric altimeter enjoys the benefit of being more stable in the short term (as opposed to GPS calculated altitude, which bounces around in the short term - if you looked at a plot of he GPS altitude, it would be a jagged line as opposed to a smooth line plot of the barometric altitude), while the GPS calculated altitude is better in the long term (as opposed to the barometric altitude which will change as pressure systems move through). Automatic calibration tries to get the best of both worlds by updating the barometric altitude every once in a while to the GPS altitude. Or, if you had accurate altitude information (i.e. from a topo map) you could calibrate it manually every hour or so and enjoy the short term accuracy.

...or select the track you uploaded and choose "tracback" and it works like a normal route.

When you use the "save track" function, it strips the track of time information. If you want to keep this information, st the unit up to log the tracks to the microSD card (see page 17 of your manual). This will generate a gpx file each day which you can then open in MapSource and view the time info.

Garmin Communicator plug-in is not supported on serial connections. Sometimes it works, but sometimes it doesn't...

If you are using the Garmin Communicator Plug-in, it's not supported on serial devices. It sometimes works and sometimes doesn't. If you are not using it, ignore me.

So what you're saying is that even though Selective Availability is off, it's still in effect. Effectively anyway. Actually, it has nothing to do with SA. Civilian receivers only use one frequency and the C/A code. Military receivers also use the second frequency and P-code. The second frequency allows the receiver to correct for atmospheric/ionospheric effects in real time rather than relying on a model. Thus, for these reasons and others, military receivers are able to reduce the errors and are consequently more accurate.

Actually, the distance to the centre of the earth varies (at sea level or on a mountain, for example; also, the earth is not a sphere, it is an oblate spheroid, the description of which is what makes up the datum, such as WGS84). But, that's not the reason behind the fourth satellite. The fourth satellite is used to solve the time issue. As you know the satellites have atomic clocks on board...very expensive. The clocks in a GPS receiver are not expensive at all (we wouldn't be able to afford otherwise). The extra satellite compensates for this imperfection. See http://www.trimble.com/gps/howgps-timing.shtml

City Nav 2008 will only unlock on ONE unit. However, you can put it on multiple computers. It also comes on DVD, not a CD, which may be a factor.

It is true that the GPSr uses doppler shift to determine velocity. Do some simple math, remembering the your position accuracy my be off by 20 feet in either direction. If you are actually travelling at, say 60 mph, you should cover 88 feet per second. But if, after a second, the GPS shows you only went 68 feet, the unit will report your velocity at about 43 mph. If it shows you went 108 feet, it will show your speed at over 73 mph. Doppler shift is accurate to about .1 mph. That has nothing to do with doppler shift. The doppler shift is the change in frequency of em radiation (or sound waves) from an object moving towards or away from an observer. GPSr uses triangulation (or trilateration) and the time it takes to receive satellite signal. The longer it takes to receive the signal, the farther you are from the satellite. By using 3 satellites, the known distance from said satellites, and the atomic clocks in the satellites, the GPSr can calculate its exact position. It can calculate speed by the change in that position over time That's a description of how it calculates position (it actually needs four satellites to get a 3D position). However, even though it could calculate velocity as a change in position, GPS's generally don't as that method suffers from considerable inaccuracy (most update at a rate of once per second, assume a position error of only 1 metre, this could result in a potential maximum velocity error of 2 m/s - that's 7.2 km/h or 4.4mph - as we all know, the real position errors are greater than that (this is the same reasoning as Sputnik 57 used above, only worded differently)). They use the dopper shift, taking into account the satellite position and velocities, working out the geometry and resolving for the reviever velocity.

Arrrghhhh! Sorry, I'm still confused but we're getting somewhere. In your first sentence, Webscouter, did you mean to say "...select the Topo maps and then use the drop down to select the CityNav maps you want."? Another thing that's been throwing me is the word "drop down" -- isn't it the "User Data Tabs" window menu to the left that I should be referencing? The "Maps" tab lists the Topo segments I've chosen OR the CityNav segments I've chosen. I highlighted the entire list of segments by going to Edit--Select All while in CityNav and then Send to Device, then did the same for Topo. After doing that, I only have Topo on my GPS. Good Gawd...why don't the manuals supply this information? Select the City Nav maps you want. Then select the Topo maps you want. Now that you have everything selected from both programs, send to device. That's it. The drop down box is the selection on the View toolbar. It is the same function as View>Switch to Product in the menus.

Since you are able to get there using your GPS consistently and others are finding the 80 foot error, it might be that you aren't using the same datum. Have you checked to see if your GPS is set to WGS84? Are the others using WGS84 (probably no way you can confirm this)? If you have WGS84 set and only a few people are reporting this error, chances are they have it set wrong.

Well, I don't know the full answer, but part of it lies due to the fact that it isn't the simple calculation you think. 1. A GPS calculates velocity from the doppler shifts (change in frequency due to motion) of the signals it is receiving from the satellites, so it's not simply distance divided by time. 2. It appears that the distance on the odometer gets calculated via integration of the velocity with respect to time. This isn't the only type of navigation system that does this. The track log distance is a measurment between the track log points. It makes sense to do this because the velocity data is stripped off the track logs when you save them, but you'll still want the distances to enable TracBack operations. 3. Thus, the problem is when the velocity reads zero, as you noted. Integrating zero velocity gives zero distance. Also, it may just not do the calculation when it reads zero. 4. One or both of two things are likely happening: a. The lower velocity gate for the HCx below which it does not work out the doppler shift is higher than that of the older models. There might be a reason for this (see my next point). b. The HCx obviously receives and processes weaker signals. These weaker signals can have more error built in, since the system is more susceptible to multi-path, etc. Also, given this condition, it is more difficult to calculate the doppler shift (signal interference causes havoc on the ability to accurately measure the frequency) at low speeds (small doppler shifts). My guess is that the lower velocity gate was raised to try to avoid the errors caused by the very weak signals at low doppler shifts. An attempt was made to lower it in one of the last updates, but it still causes problems. The older, non-high sensitivity GPS's didn't suffer from this problem, but when they lost a signal, you lost everything (i.e. time didn't change, dropouts on the tracks, etc.). You still didn't get an accurate distance if you lost a signal that the HCx would pick up. Improvements in certain areas often require compromises elsewhere. Thus, you are able to get a signal and therefore a position and track information in areas where you would not receive a signal at all before. However, the weak signals cause problems with other calculations. This is the simplest way I can explain my theory of what is going on. I don't know for sure that it is really what is happening, but it is based on my knowledge of how the system works. I personally prefer getting the signal on my HCx rather than dropping it on my Legend. As long as I recognise that the odometer works the way it does, there are work arounds that are not that difficult, so, like you, I'm not bothered by it but would be very happy if they are able to come up with a solution.

I tried it with the two end points that you state and it seems to work for me (I don't know the area). It basically gave me I-335 to I-35/35W to I-820 to MainSt to get to the airport. Distance of 785 km (about 485 miles) and a time of 7:24:29. My preferences for routing are use auto routing (obviously); car/motorcycle; try to avoid u-turns, car pool lanes and seasonal road closures; faster time and the road selection slider is in the middle. I have no route avoidances and the default driving speed. Hope this helps.

And the same for every Windows machine, even with a serial adapter, like I said earlier. It's not a Mac persecution....Everybody's in the same boat as far a Communicator goes.

Um..I think you need some sleep. The USB/Serial adapter emulates a COM port over the USB. With respect to the original problem, Garmin has stated that the Communicator Plug-in may or may not work over a serial connection, and they will not provide any customer support for it. The plug-in was designed for USB and you'd be lucky if it did work. Your best bet would be to not use Communicator and download the geocaches into MapSource or one of the other programs others use (GSAK, etc. - I don't use them so I can't help you with that). Your connection with the GPS works, just not with Communicator.

You also state (in a later post): This actually has nothing to do with Macs. Garmin does not support serial connections on Windows, either, although it may or may not work. On the Communicator download site, click on the FAQ (something you should normally do to see if there are any issues like this or to see if the program actually does what you want it to - in other words, not in an "obscure release note") it clearly states the following: Thus, you could say exactly the same thing you did, replacing "Macintosh" with "Windows". Putting the two together, since it applies to both, replace "Macintosh" with "computer" and end up with a truly absurd result.

Not sure how your rural address works, but I can tell you the fields that you can search by (you can put in what you know and it gives you options to select from): Street Number Street (includes things like "Route 2") City State Postal Code (Zip) Country For kicks and to see how it might work, I tried putting 13254 in the postal code section, but apparently, that's not a valid zip code. I also tried 195 as a street number and "Route 2" as a street name in Oklahoma and it came up with a spot on a road labelled E1515, just south of Hartshorne. I first used MapSource. However, I just tried it on my GPS (similar fields) and just puttine in Oklahoma and Route 2, it came up with Route 2, Hartshorne, 74547. The location on the map appears to be same as the MapSource one. I can't find how to put a postal code in on teh GPS. Although I don't know whether any of my attempts are valid for what you are looking for, I hope it helps.

I agree.