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planewood

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Posts posted by planewood

  1. Here's the scenario that brought about this question.

    Yesterday I did an earthcache at a bog and one of the requirements was that you needed to measure the distance between two locations, numbered posts, using your GPSr. Well we ( I ) forgot about that requirement during the walk so I had to backtrack to get the measurement and I had the opportunity to measure it twice, once going westwardly and the other going in the opposite direction back to my waiting wife.

    It was a cool drizzly day and I had 10 sats no waas with a Garmin Oregon 400t, latest upgrade, showing 4m accuracy, walking on a boardwalk over the bog. In the westwardly direction the measurement was 326m and on the return trip the measurement was 308m. I consider this a large difference over such a short distance, remember, I was on a boardwalk in an open area.

    So I wonder how accurate measurements over large distances would be seeing how some of the trail organizations are now measuring the trail distances using GPSr's.

     

    The Oregon does not have an antenna connector port but you'd be suprised at how much better accuracy you can get with an antenna.

     

    Try this: Find a spot nearby your house with no overhead obstructions and start marking that location. Mark it then let it average for about 15 seconds then record it. Repeat that about 30 times at that same spot. (or turn tracking on for 30 minutes) Then upload those locations to Google Earth and look at the points. You'll probably see them arranged in a smooth curving line.

     

    Why aren't all the points exactly the same? Cause the satellite configuration is constantly changing and the signal strength the unit is receiving is changing. (an antenna will greatly help with the latter)

     

    There generally are about 2 times during the daylight hours that the satellite configuration is optimum. Trimble has a program (free) on their website that will plot those times. Taking measurements during the optimum times can give much better accuracy than during the least most optimum times. (if you going out geocashing on a particular day then make an optimum time chart and go at the best times)

     

    I have a spot out in the center of our cul-de-sac that has a very accurate lat/lon survey. With my GPSMAP 60cx I can get 5' repeatable accuracy with an antenna under clear, cool, low humidity skys and with the readings taken during the time of optimum satellite configuration. For a $300 hand held unit that is pretty darn good!

     

    Without an antenna and during least most optimum times the average accuracy is about 40' - 50' at this spot.

  2. Does anyone make a device that would plug into a Garmin handheld GPS that would give real time tracking?

     

    Basically, all it would have to do is read the coordiates from the device and email them to an address using cell phone technology or maybe GPRS.

     

    My wife is getting lost all the time and she has no concept of compass directions, cannot read maps, and certainly can't operate a GPS. So, when she gets lost she could call me and I could get on the internet and see where she is located. I already have a 60cx so it seems like a fairly cheap add-on device could do the job.

  3. I logged into the Garmin site and entered my unit serial number and the site said that I need City Navigator 2009 Update.

     

    Questions -

     

    1) If I buy it from someplace other than Garmin, will it come with the unlock code? Several GPS places on the internet sell it in the $50-$60 range.

     

    2) If it does not come with an unlock code, will the one I used for CN Version 8 work?

     

    3) Will I have to also buy a new Unlock code from Garmin (making the Internet deals no so good)?

     

    4) Will a 2 gig card hold all the data? Currently my 1 gig card will not hold all of V8.

     

    By the way, my 60CX has worked flawlessy since I got it in 2006.

     

    Thanks

  4. With my 60Cx, external antenna on a 10' pole, using it at a time when the satellite positions are optimum, and on a clear low humidity day, I generally get around 5' accuracy. That's when comparing it to a known control station. Without external antenna or optimum conditions, generally 15'-18' or so.

     

    Optimum times for best satellite positions at a particular location can be determined using the Trimble Planning software available at their site for free.

  5. Good, reasonable advice.

     

    Why the bold above? Well, remember, there are times when as little as 5 birds will be there for you. If your roof blocks the signal of 1, 2 or 3 of them, your accuracy will be poor.

     

    I always run an antenna on my truck (a Ford Ranger) as the windshield area is small and low and the GPSr's view of the sky is limited. When in my Durango, it seems the external antenna is seldom needed.

     

    Anyway...

    With an external antenna costing less than $30 from various sources - why would someone NOT have one?

     

    I bought my 60cx to find old surveyed property corners in heavily wooded & hilly country. The Gillson antenna definitely helped there. I do get better tracks when cruisin down an interstate, but does one really need an antenna there? I think I paid $20+ for the Gillson, so that was a no-brainer.

     

    ps - I found the starting point stake from the old survey, then used the 60cx to project the distance and bearings to lat/lon for all the other corner points. The cost of the 60cx was worth it for just that one job. It got me to within 8'-10' of each of the old stakes. Some of the points were projected 1/2 mile. Most of the stakes were showing above ground only about 1" and all were covered with leaves.

     

    I also used GeoCalc to calculate the projections and got the same answers as did the 60cx.

  6. I wish all user data (points, lines, & polygons) could be on the µSD card in sub-directories of your making and only displaying those you choose to be displayed. But, Garmin doesn't seem to have a similar mindset.
    I think Garmin is a bit trapped. On one hand they have all the legacy GPSr's with 32MB or less and on the other are the newer "x" units which can have 2GB. The same strategy does NOT fit all.

     

    It's all compounded by their current Road Warrior mindset, handheld sales are declining year-over-year while car units are doubling each year. So from a return on investment point of view, putting maximun resources into car receivers, they're making the right call.

     

    Hermit

     

    Yep, and the handheld market seems to be dominated by the geocachers. Garmin is playing to the market.

  7. the popular opinion is that the gps is accurate to roughly .1 mph. there is a time lag so gps is not great for instantaneous readings, but it is very accurate with more or less steady-state speeds.

     

    Thanks for the information.

     

    And does your screeen name come from the title character of his 1897 novel Dracula based on an actual human being, or should we say inhuman being?

     

    I've compared my 60cx by measuring time between mile markers on the freeway and it is more accurate than either of my two vehicles. Within 1 MPH, or less, of the actual MPH. Been looking for a 5 mile straight stretch so I can get a better test.

     

    ps - 1 mile in 45 seconds = 80 MPH.

  8. The gps60csx is a great unit.

    But i am still waiting for a read-tracks-from-µSD-card-funktion.

     

    SOULD I BE THE ONLY ONE PERSON WHO IS LOOKING FOR THIS FUNCTION?

     

    Or is it a patent of magellan? :)

     

    I wish all user data (points, lines, & polygons) could be on the µSD card in sub-directories of your making and only displaying those you choose to be displayed. But, Garmin doesn't seem to have a similar mindset.

  9. I was wanting to use my 76csx in my truck for some off-road camping.Everyone is saying I should get a external antenna to hook to my gps since I will be using it inside the truck.My question is why should I use a external antenna if the gps is doing fine without one?I have checked it out and its working fine as is.

     

    Bushrod - here's something you can try. Without an antenna, turn your GPSr tracking on for a few short trips. Scatter these over several days and different times of the day. Then, upload these saved tracks to Google Earth and plot them out. Examine them closely in GE and make your own detrmination as to whether they follow the actual routes to your satisfaction. Hopefully the Google Earth images will be registered adequately in your area.

     

    If you can borrow an antenna from a friend for a few days, then try running the tests again and compare them to the earlier tracks.

     

    Then, make your own decision. Everyone's needs are different and what's good for one may not be good for another.

  10. Also, while new to this part of the Groundspeak forums, I am not new to the 'arts' of geographical coordinate systems or of benchmarks for that matter. I just didn't know where to go online to find more of them. Now I do! Thanks!

     

    I worked for a major oil co. for 35 years writing geographical mapping and geo-statistical software in the exploration dept. I'm quite familiar with things like 'adjusted' or 'scaled' benchmarks. Also quite familiar with the jillions of different types of coordinate projection sistems. Having been retired for about 8 years, I'm finding a lot of the significant details of all the above are starting to blur a little, however.

     

    I have taken several college level surveying courses over the years and have had training with the more sophisticated differential GPS systems. I decided to spend a little more of my kids inheritance last year to purchase a GPSr for myself. For what I needed to do, the Garmin 60cx has been a jem!

  11. Thanks PFF!

     

    I went to the noaa site and downloaded those with horizontal control within 5 miles of my house. Of the 10 or so in the list, only one (AW1864) was reported found (2004). I looked it up using GE and it appears to be very easy to find. The rest were reported not found.

     

    GE appears to be registered to within 2'-3' at the site of AW1864 (2' SW of a power pole). I'll visit the site shortly and see what I can see.

     

    My antenna is atop a 10' PVC pipe. I rigged up a carrier on the pole at eye level for my 60cx. I usually take a Trimble chart with me when I'm out tramping around. Seems to help. The antenna magnetically connects to a 2" steel washer on top of the pole. I've wondered if a larger surface plane would help. Maybe at least to shield ground reflections?

     

    I bought my GPS to find the corner stakes of some property I own up in NE OKLA. The property is not fenced and was last surveyed about 30 years ago. I was able to find all the rebar used to mark the corners. The area is heavily timbered and the 60cx and the antenna really helped. I found the pin for the starting point of the survey then calculated the other lat/lons using the old survey bearings. I am not a Geocacher. At 65 yrs old, I try to minimize my treks in the boonies!

  12. I downloaded the benchmarks from geocaching.com for my zip code (77449) and have tried to find about 10 of them. All were gone or buried under recent construction. I went out with my 60cx with an external antenna on a 10' pole and only during times of low HDOP, so I know I got fairly close to the stated positions. With all the recent construction in my area I know there has be be some visible somewhere, but where do I find coordinates for them? Is this info kept at the county or state levels?

     

    ps - the last one I checked a cable company had just dug a 4' deep ditch across it's location! I can see where it was in an aerial photo taken 8 or 10 years ago.

  13. Yep, GE images can be registered badly sometimes. Here at my house it's almost dead on. At my country place, the images are shifted east about 10'-12'. Other places I've see it off by 50' or so. Only way to know for sure is to be able to see a surveyed benchmark or triangulation station in the GE image which requires an image with a high degree of resolution. High res images in GE are usually only found around high population urban areas.

     

    But, poor satellite geometry or poor reception can cause your GPSr to be consistently off too. To help eliminate poor satellite geometry, use the Trimble Planning Software (free at the Trimble web site) and only go out when the satellite geometry is good for your area (low HDOP). To help maximize reception, use an external antenna with an unobstructed view of the sky and go out on clear days or nights when the air is crisp and dry and the HDOP is low. Clouds or high humidity can adversely affect reception. Have WAAS turned on too.

     

    If your reasonably sure that your coordinates are fairly correct, then download the highest resolution aerial photo's (jpg format) you can find and then 'overlay' them over the GE image and alligned to your coordinates. The USAPhotoMaps software (shareware) is a good way to grab large aerial photo images. It may take a large amount of stretching or squeezing and rotating in GE to get it alligned.

     

    Anyone know how GE registers the satellite images? What are they using for a basis or comparator?

  14. Kind of shocking to spend $400+ on a GPS then learn that you have to spend $100+ more to get an auto-routing map isn't it!

     

    Not quite $400, but still shocking. I got a great deal on my 76 and have some connections for the software, but still wondering.

     

    Well, each copy of CN can only be loaded on two GPSr's. When you retrieve the 25 Char. unlock code they check serial numbers. I haven't heard of anyone being able to defeat that. I guess one could if they had an assembler and knew where to poke into the code.

  15. I made my own using a cigarette lighter plug, a length of small double wire, and a couple of small plugs taken from my computer scraps box. Use red for the positive lead so you won't get them mixed up. The Garmin c(s)x series can take up to 18V on the plug. I use mine all the time when in the pickup. If you want you can put a 150ma, 10V or 12V zener diode in the line to clamp the voltage to 10V or 12V. 6V will not be enough. My testing showed that it takes at least 10V on the power plug to work.

  16. No problem. Get either the Garmin or Gillson antenna with a long cable. Surely some steel up there somewhere on top that it's magnetic base will latch onto. I got my Gillson on Ebay and it is a good one. There is another one sold on Ebay (not Gillson) that is a hunk of junk.

     

    FYI - Our family (6 of us including 4 kids) rented a motor home for two weeks up in the Canadian Rockies about 20 years ago and we still talk about that experience.

  17. I am planning a trip to Italy this summer and I will have a car. I'm trying to set up my driving routes now and upload them to my 60CSx - with only marginal success.

     

    I plug the device in and the computer sees it just fine. When I transfer the routes I've set up though, only four of them appear - and they're point to point rather than the calculated routes I set up. I'm sure there's something I don't get. Can someone help out?

     

    My apologies if this sort of thing has been discussed already. I will gladly go where I'm directed to go - sire searches have yielded nothing of any help thus far.

     

    Thanks,

     

    Specialist

     

    Try converting them to tracks then upload them. That's what I did then used the 'trackback' feature.

  18. Against my better judgement I ordered a GPS unit from WalMart because they were nearly 100 bucks cheaper than the other stores,catch was I had to order it online.Well I did that was 11 days ago and when I ordered it they said it was in stock so I paid the 3 day shipping so I would have it by the weekend and they agreed I would get it in 3 to 4 days.Well its 7 days past now :P Come to find out it was not even shipped until 3 days ago.Just wanted to let you guys know how they operate :lol:

     

    I ordered 3 Legend CX's from them about 2 weeks before christmas and they arrived the 5th day after I placed the order.

  19. Well I just got my 60 CSX. Arrived really fast. Now I need to dig into the information that came with it.

     

    Simple question for those of you that have had one for a while. The belt clip button. It seems to have some thread lock compound on the screw. I screwed it into the spot for it as finger tight as I could get it. Did not use a tool to tighten it. How good is that thread compound? Anyone have a button come loose over time? Basically my question is is there any need for concern and should I take preventative measures and put some strong lock tite or other good thread compound on those threads?

     

    Lost mine. Took if off here while back and misplaced it. I have a lathe so will make another when I need it.

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