Help!! GPS illiterate

Discussion in 'Maps, GPS and Google Earth' started by Brute, Jan 12, 2013.

  1. Brute

    Brute Well-Known Member

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    I'm extremely uninformed concerning GPS's.I need to know if a handheld unit can be used to help set up a 1000-1500 yd range. Can I set one waypoint at my bench location and then travel over rolling hills to my target location and get a straight line distance back to the bench ?What about a phone app for GPS ? Many thanks !
     
    Last edited: Jan 12, 2013

  2. rick523

    rick523 Well-Known Member

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    You could try using google earth. i know there are a couple of guys on here that went that route. Not sure about gps good question. Good luck.
     

  3. Topgun 30-06

    Topgun 30-06 Well-Known Member

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    I know nothing about phone applications, but if you mark your bench as a waypoint and then go out to where you want a target and put a "go to" back to your bench it will tell you how far it is to within a few yards on a straight line.
     
  4. squirrelduster

    squirrelduster Well-Known Member

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    Phone aps will work if you have good cell coverage.
     
  5. Red Sparky

    Red Sparky Well-Known Member

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    You can but my gps is only accurate, depending on how many satellites I am picking up, to about 15 feet. So you may be 10-30 yards off actual distance.
     
  6. Topgun 30-06

    Topgun 30-06 Well-Known Member

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    Not quite following you on that! Is that new math you're using? If it's accurate to within 15 feet, how did you come up with the comment that it's off 10-30 yards?
     
  7. tomt

    tomt Well-Known Member

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    Make sure WAAS is enabled.
    Make sure your Map Datum is set to WGS 84
    Distance is Statue
    Position Formay is hddd°mm'ss.s"

    Now this is only true is Latitude.
    Every minute of latitude has 1850+/- meters, there 60 seconds in a minute. So every time the seconds change once you have gone 30.83 meters (1850/60=30.83). But your seconds is broken down into tenths, so when the tenths change once you have gone 3.08 meters or about 10 feet. (30.83/10=3.08)

    This all theroetical in a perfect world which we do not live in. Our handhelds CAN NOT measure that accurate, it can get us close. When you have a GO TO fuction, for the first tenth of a mile it will measure in feet, after the first tenth it measure in tenth of mile up to a mile. So if you want to measure a 1000 yds. and get it accurate, you will have to do it in increments of 500 ft. Now remember this only true north and south.

    Or use your Range finder.
     
  8. Topgun 30-06

    Topgun 30-06 Well-Known Member

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    I think you are making things much more complicated that necessary, regardless of the direction he wants to set up his range. All he really needs to do is set a waypoint on his GPS where the shooting bench will be. Then by going out to an approximate distance where his first target will be and hitting the "Go To" function he will know if he needs to go a little further out or come in a little until the distance is what he wants. Then he can set that spot as his next waypoint and keep right on doing that all the way out to infinity if he wants to. Most of the units will be accurate within 12-15 feet with WAAS enabled and that should be close enough for what he wants to do.
     
  9. Brute

    Brute Well-Known Member

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    Topgun- That's sorta how I thought it would work. Many thanks.

    Brute
     
  10. rick523

    rick523 Well-Known Member

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    Ok I guess I must be gps illiterate also what is WAAS?
     
  11. Topgun 30-06

    Topgun 30-06 Well-Known Member

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    Somewhere in most GPS setups there will be a function to either turn WAAS on or off on the unit. Anyway, here is the explanation to get better accuracy out of almost any GPS.







    Wide Area Augmentation System

    From Wikipedia, the free encyclopedia

    Jump to: navigation, search
    "WAAS" redirects here. For other uses of the acronym "WAAS", see WAAS (disambiguation).
    [​IMG][​IMG]
    FAA WAAS logo



    [​IMG][​IMG]
    WAAS system overview



    The Wide Area Augmentation System (WAAS) is an air navigation aid developed by the Federal Aviation Administration to augment the Global Positioning System (GPS), with the goal of improving its accuracy, integrity, and availability. Essentially, WAAS is intended to enable aircraft to rely on GPS for all phases of flight, including precision approaches to any airport within its coverage area.[1]
    WAAS uses a network of ground-based reference stations, in North America and Hawaii, to measure small variations in the GPS satellites' signals in the western hemisphere. Measurements from the reference stations are routed to master stations, which queue the received Deviation Correction (DC) and send the correction messages to geostationary WAAS satellites in a timely manner (every 5 seconds or better). Those satellites broadcast the correction messages back to Earth, where WAAS-enabled GPS receivers use the corrections while computing their positions to improve accuracy.
    The International Civil Aviation Organization (ICAO) calls this type of system a satellite-based augmentation system (SBAS). Europe and Asia are developing their own SBASs, the Indian GPS Aided Geo Augmented Navigation (GAGAN), the European Geostationary Navigation Overlay Service (EGNOS) and the Japanese Multi-functional Satellite Augmentation System (MSAS), respectively. Commercial systems include StarFire and OmniSTAR.
     
  12. rick523

    rick523 Well-Known Member

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    30-06
    Thanks, I guess I'm on a search through my gps now, hope I don't get lost on the way:rolleyes:
     
  13. GPutt33

    GPutt33 New Member

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    First post here, so I hope I'm welcome.

    I've been using GPS's since the very first civilian Magellan came out. I became kind of a GPS geek I guess and have ended up as an instructor for sheriff depts, search and rescue squads as well as a few corporations.

    All of the info posted so far is correct. The WAAS system has increases the accuracy. If you have a screen showing active satellites most units will show you the WAAS satellite location as well. I do like setting the unit up on the WGS-84 grid because this compatible with Google Earths coordinate system. I like setting the coordinates to read in Decimal Degrees because this makes it much easier to input not only in map programs but is also the only one you can easily use in Excel.

    Saving a waypoint of your shooting bench is the first step. Proceed on out to where you want to set up your targets and go-to your saved bench waypoint and it will give you straight line of sight accurate to within 15'. Just make sure when doing this for accuracy you have optimal sat coverage at the time, it does change constantly.

    The worst piece of info off a GPS is elevation. Think about standing in an egg with 15' out to the shell. The narrow pointy end of the egg is above your head and may be off by as much as 100'+.

    Make any sense? Hope so :)
     
  14. Nimrodmar10

    Nimrodmar10 Well-Known Member

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    I'm like the other guy, past about 200 yards my Garmin measures in .1 mile increments. A tenth of a mile is 528 feet or 176 yards. That means your target range can be off by plus or minus 175 yards, or up to 350 yards. I can guess closer than that. Am I figuring that right?