I work in a mountain search and rescue team and in order to locate victims or areas we are using a « GPS Binocular » which allows you to point to a place and get its lat/long coordinates + distance with only the click of a button. Problem is that the range of the binoculars is limited (1km maximum) and it is above all super heavy (more than 3 kilograms).
Last week I thought about building my own « GPS Gun » based on Arduino.
What it needs looks (at first) very simple : a laser range finder module ; a gps chip ; an lcd screen, a compass and that’s it !
The principles on which it would work : you aim at the area you want to search ; you push the button and the range finder calculates the range while the compass calculates the azimuth ; the device then uses your gps coordinates to compute the victim’s coordinates by adding the distance and the direction.
But unfortunately it only looks simple… My first problem is finding the right rangefinder laser module for Arduino.
After some research, all I’ve find are ultrasonic modules (too short in distance for me) or laser modules that work only up to 50-100 meters…
Then I found william’s project, which looks extremely close to what I want to do : Very long distance sensor
But has not been completed.
So first question would be : Does anyone know of an arduino laser rangefinder module that would work past the 500 meters limit ?
Hi Horace and thanks for your answer !
Indeed, some golf/hunting rangefinders are capable of measuring up to 1km (even more).
Problem is that they do not give coordinates, and above all they get extremely expensive above the 1km limit…
EO/IR (a COTS field) has had the ability to Geolocate/LRD well beyond 10km, and that was almost 20 years ago, so it's only better, smaller, lighter and less expensive. Atmosphere is the only thing that isn't changing (because it always is). One (e pluribus) example:
It is not clear what distance you are looking for. How far past 500m? 1km? 2km? 10km?
If they did, then they'd be the thing you are trying to build.
What you want is a rangefinder that has digital output (RS232, I2C, SPI...), so it can talk to your Arduino device. Something like this:
Or, you must be willing to manually enter the distance from a rangefinder into your Arduino device (or speak the distance, if you use a voice recognition module...maybe not a good idea in a chaotic, noisy search environment).
Edit to add:
If the operator of your device will be above or below the location of the subject, then you may need to correct the rangefinder's reported distance, because to do your coordinate calculation, you need the distance to the subject in the horizontal plane, not the straightline distance. The error in using the straightline distance can be significant; e.g., about seven percent at 20 degrees and 15 percent at 30 degrees.
Also, I've been involved in wilderness and avalanche SAR and am interested in how you are using this device. Would you please elaborate on this?
How do you use the device to "locate subjects" (the common US term used in lieu of "victim")
How do you use, and what is the use of, "locating areas" with the device?
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Edit #2 to add: On the other hand, I can see how this would be useful for a scout to target artillery.
I found the Jenoptik LDM301 which can measure distances up to 3 km! ... if the target has a retroreflector on it. For natural surfaces, they expect 1/10th that range.
Can you get topographical data on the search area? From the GPS you deterine your location and from the topographical data, you get your altitude above mean sea level (compare with GPS-calculated altitude as a cross-check). From an accelerometer and compass, you determine the altitude (angle above or below the horizon) and azimuth (compass direction) of the target. With the pointing direction and the topographical data you calculate where your pointing vector first intersects the ground and that is the location of the target. No rangefinder needed.
If they did, then they'd be the thing you are trying to build.