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Old-Time Wanderers

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Everything posted by Old-Time Wanderers

  1. I just recalibrated my barometer using the pressure given by www.weather.com. When I turned off the " Use with GPS" and inputted the pressure I "adjusted" for my actual altitude, I got a reading that was way too low. When I inputted the "given" pressure at sea level, my altitude was correct. I must conclude from that test that the GPSr takes the "actual" pressure at "actual" altitude, and subtracts it from the sea level pressure. It then determines the actual altitude from that result. Bottom line is get the sea level pressure from any of the above sources, and input it as your pressure at your location. The GPSr will do the rest automatically.
  2. I'm sorry. I see that I wasn't clear at all in my response. I didn't mean that the pressure was correct at your altitude. Just that it was correct at your location (at sea level). That's why I provided the conversion factors. Pressure decreases be about 1 inch of mercury (1.0"Hg) for each 1,000 feet that you increase in altitude. It loses goes down by about 0.1"Hg per 100 feet and 0.01"Hg for each 10 feet. If you are near Reno/stead airport (FAA identifier 4SD) your elevation is about 4,214 feet. If you are near Reno/Tahoe International (FAA identifier RNO) then your elevation is about 5,050 feet. Let's say you're near Reno/stead. Your pressure from weather.com is 30.00"Hg. The pressure you would key into your GPSr would be 25.79 (reduced 4.21) for your altitude of 4,214. If you are near Reno/Tahoe Int., you would input 24.95 (reduced 5.05) for your altitude of 5,050 feet. While it's not exact, it gets you into the ballpark. Again, I'm sorry if I confused. It's usually better to just use the "calibrate by GPS" selection. Just select "no" for the questions of "do you know the correct elevation" or "Do you know the correct pressure." Another way is to simply pick up a topographic map of your area, locate your position and key that in as the "correct altitude."
  3. I have a GPSMAP 76 cs and use my iMac flatscreen G4 to generate waypoints from National Geographic's Topo State series. Unfortunately, Garmin supports PCs only. I bought a Gilsson USB to serial adapter and a garmin serial connector (round four-pin plug to a nine-pin serial connector). i connect them together and load the waypoints via my Mac's USB. I run OS 10.3.8 so I downloaded the latest drivers the web site to which Gilsson sent me. See my post about the USB drivers for Mac OS X on 3/18/05. They work flawlessly.
  4. No, the calibration is at your location. Go to www.weather.com and get your local weather by typing in your zip code. Your local weather will provide the barometric pressure for your general location. Unless you are in the mountains, the pressure should be pretty close to what it is at your location. If you are using inches of mercury, each 1/100th of an inch of mercury equals about 10 feet in elevation for example, at an ambient pressure of 29.92 at sea level, your pressure will be about 29.90 if you are 20 feet above sea level. Your autocalibrate by gps should come within about 9 feet (3 meters) of your actual elevation. Just use the barometric pressure on www.weather.com and you'll be in the ball park.
  5. Hmmm. Now that is really strange. The message I received when I downloaded the updater was that I would have to reload all my POI. Because of that, I downloaded an additional file that turned out to be the Americas Marine and International Marine. When I loaded the international marine, it took out all of my maps. I had to run the 3.70 updater again and then I had the Americas highways back. Very interesting. At least I got the Jumpmaster in setup (as though I'm going to jump out of a perfectly good airplane).
  6. Be careful when you load it. You will also read that you have to reload the POI files. They are the Americas Marine and International Marine. If you reload the Marine, it wipes out all of your land maps. I'm not sure if you have to reload the Americas base map or not. but the marine basemap replaced my Americas basemap and all of my city select and topo maps. At least they didn't show in the Maps <menu><setup map><menu> selection.
  7. For all you poor benighted Mac OS X users who have been lamenting not having drivers for the USB to Serial cables we have to use, here is the web site for drivers for the Gilsson USB to Serial cable. The site is http://tech.prolific.com.tw/visitor/v_fileBrw.asp. Enter OS X into the search box, and select the PL-2303 package. I downloaded it last night and transferred my waypoints, routes, and tracks from my GPSMAP 76 CS to my National Geographic TOPO! State Series map. It worked perfectly. I even sent my waypoints from my map to my GPSr and that worked perfectly also.
  8. I think I must be doing something wrong because I haven't been able to convert any *.loc Geocache database files to GPX files. I'm using MacGPSbabel Version 1.2.5 beta on an Imac 800 Mhz machine with 10.3.8. Everytime I select "Geocaching Database" as the source file, and "GPX XML" as the destination file, as soon as I hit the convert button, I get a message that the conversion failed. I've tried to read the readme file, but haven't found any instructions for converting files. Do my GPSr have to be connected or can I convert it to a file on my hard drive to be uploaded to the GPSr at a later date. Everything I read here indicates that the software works. I just can't figure out how to use it.
  9. Amazon has some great bargins. They had my GPSMAP 76CS for $404. If you also got their visa card, they take off an additional $30 and give you 6-months at zero percent interest. Basically, I got my 76 CS for $374 and get to pay it of at about $61 per month. Can't beat that with a stick.javascript:emoticon('')
  10. It refers to a statute mile (which is what you use on your hwys) as opposed to a nautical mile (when you hear a ship travelling at 10 knots, it is travelling at 10 nautical miles per hour -- BTW, knot and nautical mile just happen to be coincidental terms. The knot actually refers to the knots in a rope that used to be used for measuring speed.). A nautical mile is 1.15 times longer than a statute mile. Not that I know of. GeoBC Another "nice to know" about nautical miles is that each minute of latitude equals one nautical mile. That's particularly helpful when you're looking at a map and don't have a scale.
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