Range Report need help on GPS
- Thread starter lilgreg
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Re: need help on GPS
The short answer is you can't/shouldn't use a GPS to read distance between two points and the elevation. Get a rangefinder and perhaps an angle indicator.
There are ways it could be done, all involving knowing the location of both points. You could visit both points and mark off the distance. (Some GPS units either come with or can load aerial/satellite imagery so you might be able to place your point downrange without visiting it). And there are certainly a couple of mathematical methods like the Great Circle distance or the more accurate Vincenty formula...but who wants to do a s-load of math just to take a shot?
The short answer is you can't/shouldn't use a GPS to read distance between two points and the elevation. Get a rangefinder and perhaps an angle indicator.
There are ways it could be done, all involving knowing the location of both points. You could visit both points and mark off the distance. (Some GPS units either come with or can load aerial/satellite imagery so you might be able to place your point downrange without visiting it). And there are certainly a couple of mathematical methods like the Great Circle distance or the more accurate Vincenty formula...but who wants to do a s-load of math just to take a shot?
Re: need help on GPS
yes i under stand but i am shooting 1 mile it is hard to range with my range finder off hill sides with woods and i was wanting to check my mil my angle and my ballistic ability at longer ranges it is hard to find that kind of open distance around here and i was hoping somebody new of a simple GPS that a person could download into a smart phone any help would be appreciated
yes i under stand but i am shooting 1 mile it is hard to range with my range finder off hill sides with woods and i was wanting to check my mil my angle and my ballistic ability at longer ranges it is hard to find that kind of open distance around here and i was hoping somebody new of a simple GPS that a person could download into a smart phone any help would be appreciated
Re: need help on GPS
<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: lilgreg</div><div class="ubbcode-body">what would be the best GPS to download into phone to read distance between two marked points and elevation difference </div></div>
Not a clue on if a phone GPS will do an angle but here is a suggestion,
Get a GPS that does measurements in feet.
1. go to target, mark it
2. go to firing position, mark it
3. Calc distance in feet and convert to yards, meters, whatever you like
4. get an angle indicater(I got mine frome Home Depot, paid $14 US) and measure the angle
5. correct for angle
6. shoot
or for step 4. do the math using distance and elevation diffrence between target and firing position
(yeah baby! trigonometry is now something you wish you remember from High School or there may be a separate app for that)
or you can buy a $150US gizzy-wiz you bolt on your rifle to take an angle measure.
<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: lilgreg</div><div class="ubbcode-body">what would be the best GPS to download into phone to read distance between two marked points and elevation difference </div></div>
Not a clue on if a phone GPS will do an angle but here is a suggestion,
Get a GPS that does measurements in feet.
1. go to target, mark it
2. go to firing position, mark it
3. Calc distance in feet and convert to yards, meters, whatever you like
4. get an angle indicater(I got mine frome Home Depot, paid $14 US) and measure the angle
5. correct for angle
6. shoot
or for step 4. do the math using distance and elevation diffrence between target and firing position
(yeah baby! trigonometry is now something you wish you remember from High School or there may be a separate app for that)
or you can buy a $150US gizzy-wiz you bolt on your rifle to take an angle measure.
Re: need help on GPS
the reason for feet is it is usually the smallest unit of measure available, the larger the unit of measure the bigger the rounding error.
For example .01 of a mile is 17.6 yards,
the reason for feet is it is usually the smallest unit of measure available, the larger the unit of measure the bigger the rounding error.
For example .01 of a mile is 17.6 yards,
Re: need help on GPS
In short, get a better rangefinder. A Swaro LRF will not always do it, depending on conditions, but I have gotten readings out to 1910 yards.
With consumer-grade GPS units you will be lucky to get within +- 12 ft. with either point. The best I've ever seen is with a DeLorme PN-60, which occasionally locks in to 6ft. (I program with cell phone GPS and rarely get below 20 ft). So that means you've got a potential error between the two points of 24 ft. (or 8 yards). Supposing you calculate the distance between the two sets of coordinates exactly...and that's supposing a lot, especially under time pressure...you're going to potentially be off by 8 yards or more. At 1760 yards, that means a drop off by roughly 30" (for a typical .308 load). Add any incline angle and your potential out at those distance for missing the shot will only increase.
In short, get a better rangefinder. A Swaro LRF will not always do it, depending on conditions, but I have gotten readings out to 1910 yards.
With consumer-grade GPS units you will be lucky to get within +- 12 ft. with either point. The best I've ever seen is with a DeLorme PN-60, which occasionally locks in to 6ft. (I program with cell phone GPS and rarely get below 20 ft). So that means you've got a potential error between the two points of 24 ft. (or 8 yards). Supposing you calculate the distance between the two sets of coordinates exactly...and that's supposing a lot, especially under time pressure...you're going to potentially be off by 8 yards or more. At 1760 yards, that means a drop off by roughly 30" (for a typical .308 load). Add any incline angle and your potential out at those distance for missing the shot will only increase.
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