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smithcon

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Everything posted by smithcon

  1. Doppler shift would make sense for a speed reading, and I would be impressed if these little handheld units did it. It is too late in my head to ponder the algorithms, but if you consider the rotation of the Earth, the movement of the satellites and the curvature of their orbits, etc, I know I wouldn't want to do it with my slide rule. I guess it would be possible. If it is true I will give regard my GPS V with even more respect than I do already.
  2. smithcon

    GPS V problems

    My V has had no problems like this for over a year in heavy use for navigation and occasional geocaching. I have had the DC power problem, which I could probably fix by taping the batteries to prevent shakage on bad roads, but it has not been frequent enough for me to bother.
  3. Sorry, my last post was from a failed post attempt from last night, and I realize it is somewhat redundant considering the new posts on the topic since I first started drafting it. So feel free to use it for an insomnia cure; I'm sure you will find it effective. Regards, -Greg
  4. Here's a bunch of useless ramblings on the subject: A well-written article in either Car and Driver or Autoweek within the last five years explained why speedometers are almost always calibrated to read slightly over the true speed, with european-produced cars the worst offenders. I don't remember it all that well, but I do recall that in Europe, or at least parts of Europe, manufacturers pay a fine for producing a car whose speedometer reads too low under any circumstance. Manufacturers also had concerns about liability and are concerned that if all of the tolerances and conditions end up the wrong way (oversized or over-inflated tire, under-sensitive servo on the needle in analog speedos or long lag time on early digital speedos, tire speed differential on long curves, etc) that they will turn a car out the door with a sometimes under-reporting speedo, causing the customer to speed unwittingly. Thus, they design in a "cushion", most aggressive (5MPH over at 60MPH in some cases studied) in many euro-cars because of the laws and fines, to make sure the "worst" case is an accurate speedometer. I remember Japan and America were different, but I can't remember which produced the 2nd-biggest cushion on average. I think it was Japan, but I am not sure. My American-built Japanese sedan seems to underreport pretty substantially, 4-5MPH at 60MPH, based on my GPS reading on long, open, straight roads. Now, for some really useless ramblings, remember the Heisenberg uncertainty principal; you cannot determine both the precise location and precise velocity of any object. The more precisely you measure the location, the less you know about the velocity, and visa-versa. A GPS measures your location at a certain instance in time. A single GPS location fix knows nothing of your velocity. Multiple fixes over time are averaged for a velocity calculation, but of course that is merely an average speed between two or more points. But which points? When and where were they taken? Where, in fact, were you really going exactly that speed? See? If you know the velocity, you don't know the location! :^} Seriously, a GPS speed with a strong fix series should be very accurate with decent satellite geometry (which should yield a high accuracy reading on your receiver), no blockage, and a straight level road at a constant speed. Speed variation turns a GPS into the world's slowest-refreshing digital speedometer, yielding random intermediate results. Turns are just as bad, especially when you are turning more than 15 degrees between average-basis fixes, as they introduce geometry changes between your point fix lines which are likely not smoothed well by the speed averaging algorithm, so toss out those speed readings too. Since roads are generally not steep enough to make a significant mathematical difference in the speed calc most of the time, small grade changes are a lesser factor. So you are left deciding between a cable counting the rotations of an uncertain-diameter wheel over time, or averaging location fixes over time. Good fix GPS in straight, unblocked territory with constant speeds is your best bet (even intermittant blockage is okay if your speed is constant and reflected signals are not a problem) . Choose the speedo for other moments. Challenging a radar gun in court is not impossible, but a lawyer does it best. Unfortunately, the court is unlikely to put more faith in your gadget than the officer's. Most radar tickets are won on the picking apart of technicalities of the procedure used to determine the speed with the radar gun (Were all procedures in the radar gun manual followed by the officer? Imagine answering questions in court about the operating methods from one of your electronic gadgets. Again, lawyers experienced with this can do this well, according to what I've read, but I know I couldn't pull it off.) It is probably much cheaper to go to court and hope the officer is a no-show. If you don't want to try that, you might get a big reduction in fines simply for showing at the hearing date on your ticket and offering a "my bad! I'm sorry, I didn't speed intentionally; I was just keeping my eyes on the road and forgot to check the speedo. When I first saw the officer flashing to stop me, I glanced down and saw only 69 on the speedo." sort of speech. Good luck.
  5. The best part about the bean bag mount is that you can instantly and effortlessly grab the whole unit, mount and all, off the dash, program it in your hands (as passenger or (parked) driver) and put it back on the dash. As a tall person, the unit it awkwardly far away to program because my seat is so far back. A variation of this is that I can hand the unit to anyone in the car, including someone in the back seat, to read detailed info off when needed. I have had the unit beanbag mounted on the dash for over a year between my two vehicales and have had only two minor slipping incidents -- perhaps my dashes are less slippery than others? I corner fairly aggressively when I am alone (passengers object), but both of my slipping incidents have been under hard acceleration (my dash slopes away from the windshield, causing acceleration to be the most dangerous). In both slipping cases, the slip was slow and gradual, because the high-friction undermaterial prevents it from sliding easily.
  6. that's kind of missing the point. By virtue of my extremely busy work/family life, I am by all accounts a very occasional geocacher (I received the V for other purposes and then discovered the game), but my V is with me all of the time. So, it is great for geocaching, but it can also work its way into your life, replacing maps and mapquest.com and such, and offering all that knowledge on the fly with no pre-planning. Any time I want to go somewhere new, or deviate from a known course because of a traffic jam, the V is a capable navigator. Once you have the power of automatic, self-adjusting autorouting whenever you want it, you will realize what an enormous time/argument saver it is. Especially if you hate to stop and ask for directions like I do. Just ask my wife. As far as geocaching is concerned, it stands with the best of the handheld units. Although bigger than the tiny units, the triangular profile is very comfortable to hold, and allows the unit to perform equally well in both hand-held and dash-mount modes. You don't have to use the autorouting to find the best parking spot if you want to maximize the challenge, but the option is a few button pushes away should you want to make it happen. Would I recommend that buy a V JUST for geocaching? Not if you were on any kind of budget. But if you are prepared to let the V earn its living being your navigator, and you are given to spontaneous exploration, there is no better bargain around.
  7. N7YUV here - ham since 92 (used for field seismology when I first got it). I have never used it for caching, but I always carry it with me in the trunk and take it with me for long hikes or backpacking trips.
  8. That 2-unit policy does ring a bell now that I think about it; Now to see if a pre-deluxe V can be acquired new or used ... I will also contact Garmin and let them know that my unit was lost, just in case they can file that info away somewhere.
  9. That's right, I lost my Garmin V after a geocache hunt in Cedar Mill park in Beaverton, OR. I played football with my son in the park after our cache find, and probably lost it from my pocket during a heroic maneuver. ARRRGGGHHH! It actually happened almost two weeks ago. As soon as I realized it was missing (the following evening when I went to pull it out of my briefcase), I made a hasty trip to the park on the first rainy night we'd had in recent memory. Hoping to find a soaked but reviveable unit, I returned only with a profound sense of loss. Not only for the monetary value, but for what had become my constant and most reliable traveling companion. Yes, my trusty V had replaced all of my map books, my folding maps, my hardcopies of Mapquest driving directions, and my wife's frustrated attempts to read them in a moving vehicle without hurling. My V had it's quirks, to be sure. Occasionally, it would take a second longer to refresh than I would like, or tell me I was off route when I was still in the middle of the freeway. It even encouraged me to break the law a couple of times, but it never left a huge pile of unfolded and unkempt paper in my car, had pages rip out of it from overuse, made me curse at how inconvenient or slow the internet was, and best of all, it never yelled back when being impatiently consulted for an alternate route. My view of the device has gelled considerably since I reviewed it last time. Sure it wasn't perfect, but it WAS good enough to trust to get me there, EVERY SINGLE TIME. I might make a wrong turn, but it would always bring me around in FAR less time than it would take me to swear, pull over, flip open the tattered Thomas Guide I kept under the passenger seat, and try to memorize a new route. It tought me numerous obscure but extremely useful shortcuts on my frequently travelled routes, and patiently beeped at me when I wasn't paying attention. I have completely removed all maps from my car, and have never regretted it. It also became a constant companion on hiking and biking trips. If you have any doubts as to the usefulness of the V as a navigator, I would consider it a peer to the best car navigation systems in terms of accuracy. (It gave equal or better directions than a 2001 Acura RL NAV system when used side-by-side on five trip segments in Portland and Seattle.) As a hiker or biker, it was flawless. Great signal lock reliability, and good readability. The form factor is more comfortable for hand holding, although heavier than, an etrex. I acquired this in spring from tvnav.com, and upgraded to the all-zones unlock for $50. Now I must come up with a replacement plan. Can I use my upgrade certificate on another pre-deluxe V? Does anyone have a pre-deluxe V they want to sell? Would any Garmin retailers have any remaining pre-deluxe Vs for good prices? If I need to buy a new one, I will re-use tvnav.com, as they were very knowledgeable and gave great service the first time around.
  10. As soon as I read your post, I realized you were correct. In any case, the few inches of clearance afforded by tires, even if they were perfect insulators, would not offer much protection from a bolt that spans ground to cloud. It was information told to me as a child while in a similar situation in the Colorado rockies, and of course I had no reason to question it then. We did have the good sense to keep away from grounded metal surfaces in the car.
  11. I was just on a cache hunt last weekend, starting my second attempt at finding Wild Arboretum, my enthusiatic six-year-old assistant leading me by 20 yards ... A deep, dark cloud suddenly appeared over the tree line and quickly moved into position over us. In Portland, this usually means nothing more than you are about to look like you just went over Niagra Falls in a leaky barrel. Beckoning my son to turn back, I was interrupted by one blinding fl -- what the -- make that THREE flashes of --- WOW THAT THUNDER IS LOUD! Less than a second between the flashes and the eardrum-splitting explosions, I think to myself as I notice my son no longer seems to be ignoring my weather admonitions, seeing as how he has already had the good sense to run past me on the way back to the car, leaving me for dead where I stood. Okay, about 5 seconds per mile, that makes those thunderbolts precisely, oh, about death ray range of both of us at any instant, I think inside while I try to reassure and comfort my son with my calm, trembling exterior. 1000 strikes a year in the U. S., I recollect, but only about a third of them are fatal, right? Hurrying back toward the car, another flash brings a good two-second pause before hurtling a somewhat more subdued thunder crack at our ears, which I realize are still ringing from our first death-defying (deaf-defying?) encounter. Amazingly, we both arrived at and entered our comfortingly rubber-insulated-from-the-ground car before a drop of rain fell, which was good because we didn't have to wait two minutes before an amazing cloudburst absolutely rendered my windshied wipers useless on their most hysterical setting. We never witnessed another flash, but we heard another thunderclap or two. It was all gone in ten minutes as suddenly as it came, but we didn't resume the hunt that morning since we assumed the trails were muddy enough to get us in serious trouble with my wife. In conclusion, I don't know how or if the lightning affected the reception or accuracy of my receiver. Frankly, I don't even know how my receiver made it back to the car that day, as I have no recollection of carrying it back. I do know, however, that lightning can have a direct and dramatic effect on the geocacher.
  12. No extra work is required just to keep them in non-geosychronous orbits -- they are closer to Earth so they orbit at a faster rate, but their orbits are still nominally stable orbits. Geosynchronous orbits are simply orbits that are placed directly over the equator and at a distance that allows the orbit speed to balance out at the same revolution rate that Earth happens to spin. From an orbital mechanics point of view, there is nothing special about geosychronous orbits. It's just like the planets around the sun. Like Earth, Mercury is in a stable orbit around the sun, but it is much closer so must travel must faster to stay in orbital balance. Not having the GPS constallation confined to the equator line, as the previous poster pointed out, helps increase accuracy and reception everywhere in the world.
  13. Hello from N7YUV (Portland, Oregon). I may be new to Geo-caching, but I am an old Ham!
  14. Autorouting is aware of one-way streets, at least in downtown Portland. I simply don't use maps anymore. It does have minor issues; it has directed me to turn right at an intersection that forbade such a turn because of a parallel road that was "merging" into the road I was on at that awkward intersection. However, I just continued straight and was directed on a new correct course within twenty seconds or so. I have also intentionally deviated off of auto-routed roads to avoid traffic, and allowed it to come up with new routes for me on the fly. There really is no need to use maps anymore (at least in cities)! Generally, it plans routes about as well as I would by looking on a good detailed map (or even better in some cases, since it seems to have some built-in knowledge about the quality of the roads), since mistakes can be made there as well. It's just that you have no need to pull the map back out if a problem with the route develops, since the V automatically does that for you. A few times it has given me seemingly unproductive turning instructions on routes to familiar places, and I have followed them out of curiosity. Even in these circumstances, it has always gotten me to my destination and taught me interesting driving alternatives. In about half of these cases, I have discovered excellent hidden shortcuts! There is one thing that could be improved upon: If you deviate off course, and you are driving on a continuously twisty, curvy road, it takes autoroute much longer than normal to recalculate for some reason. My workaround is to stop the car on the shoulder for a few seconds to let it catch up with itself. However, if I were map-navigating, I would be stopped much longer unless I had a live navigator riding shotgun -- one who doesn't happen to get car-sick reading maps underway on continuously curvy, twisty roads. I have no experience with other civilian units, but the V has proven to be an excellent all-around car/bike/hike unit for me. [This message was edited by smithcon on May 25, 2002 at 06:06 PM.]
  15. Autorouting is aware of one-way streets, at least in downtown Portland. I simply don't use maps anymore. It does have minor issues; it has directed me to turn right at an intersection that forbade such a turn because of a parallel road that was "merging" into the road I was on at that awkward intersection. However, I just continued straight and was directed on a new correct course within twenty seconds or so. I have also intentionally deviated off of auto-routed roads to avoid traffic, and allowed it to come up with new routes for me on the fly. There really is no need to use maps anymore (at least in cities)! Generally, it plans routes about as well as I would by looking on a good detailed map (or even better in some cases, since it seems to have some built-in knowledge about the quality of the roads), since mistakes can be made there as well. It's just that you have no need to pull the map back out if a problem with the route develops, since the V automatically does that for you. A few times it has given me seemingly unproductive turning instructions on routes to familiar places, and I have followed them out of curiosity. Even in these circumstances, it has always gotten me to my destination and taught me interesting driving alternatives. In about half of these cases, I have discovered excellent hidden shortcuts! There is one thing that could be improved upon: If you deviate off course, and you are driving on a continuously twisty, curvy road, it takes autoroute much longer than normal to recalculate for some reason. My workaround is to stop the car on the shoulder for a few seconds to let it catch up with itself. However, if I were map-navigating, I would be stopped much longer unless I had a live navigator riding shotgun -- one who doesn't happen to get car-sick reading maps underway on continuously curvy, twisty roads. I have no experience with other civilian units, but the V has proven to be an excellent all-around car/bike/hike unit for me. [This message was edited by smithcon on May 25, 2002 at 06:06 PM.]
  16. I also had a very good no-hassle experience ordering from tvnav.com. I used the cheapest shipping option, got it when it was promised and was surprised to see that it had a firmware version on it that Garmin had released only a couple of days before my order! I recommend them highly.
  17. I haven't cached yet, but I have used my V for hiking and am very impressed with it in that mode. It is perfectly shaped for hand-holding, with the triangular profile feeling very natural in my hand. The bearing and course indicator screens are clear and easy to use, with lots of configurability. I have even used it for walking to restaurants downtown. The POI database it comes with is quite thorough in that regard, and you can use off-road mode to get to any POI, intersection, or address while walking, thus taking advantage of the numerous undriveable shortcuts that crisscross dense urban settings.
  18. I haven't cached yet, but I have used my V for hiking and am very impressed with it in that mode. It is perfectly shaped for hand-holding, with the triangular profile feeling very natural in my hand. The bearing and course indicator screens are clear and easy to use, with lots of configurability. I have even used it for walking to restaurants downtown. The POI database it comes with is quite thorough in that regard, and you can use off-road mode to get to any POI, intersection, or address while walking, thus taking advantage of the numerous undriveable shortcuts that crisscross dense urban settings.
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