Welcome to PhantomPilots.com

Sign up for a weekly email of the latest drone news & information

LOS Calculator?

Discussion in 'Pro/Adv Discussion' started by wallix, Apr 27, 2016.

  1. wallix

    Joined:
    Jan 5, 2016
    Messages:
    74
    Likes Received:
    22
    Is there a website that can roughly calculate the height you'd need to fly to keep LOS on your drone given a certain distance?

    I want to use Litchi to fly my P3A straight to my friends house. It's about 7500ft in a straight line. I just want to know the altitude I can set it to keep LOS with the controller. Right now I have it at 300ft, which is just a guess. The terrain is fairly flat the whole way.


    Sent from my iPhone using PhantomPilots mobile app
     
  2. Ed209

    Joined:
    Jul 27, 2015
    Messages:
    938
    Likes Received:
    423
    I always wondered what the formula was for calculating angle of altitude at and given distance. Even if it's just assuming a flat terrain. For example: on super ling distance flights over water. Even at 9mi it seems like the bird is only 10deg off the surface.
     
  3. tcope

    Joined:
    Jan 29, 2015
    Messages:
    3,530
    Likes Received:
    1,389
    Location:
    Salt Lake City, UT
    Do you live in an area that is perfectly flat with no obstructions... such as houses or trees? If not, then any such calculator will not help.
     
  4. Ed209

    Joined:
    Jul 27, 2015
    Messages:
    938
    Likes Received:
    423
    Sure it would. Just like I said if at 9mi you need to maintain a 10deg angle for LOS then if anything gets in between you know it's an issue.
     
  5. sar104

    Joined:
    Mar 22, 2014
    Messages:
    1,265
    Likes Received:
    245
    Location:
    Los Alamos, NM.
    I'm not sure that this is a well-posed question. Loss of LOS can be due to a number of factors, and terrain is only one of them.
    1. At the global level, the curvature of the earth is going to obstruct LOS at some altitude-dependent distance - simple Euclidean geometry. Valid over bodies of water.
    2. On a more local, topographic level, mountains, hills or even more subtle elevation changes may cause loss of LOS - a more complex calculation requiring a DEM for the terrain. Valid over bare landscapes.
    3. Even more locally, trees, buildings and other structures may cause loss of LOS - very difficult to calculate since even the best DEMs do not, typically, include buildings and vegetation. Probably the most common obstruction to LOS.
    In all three cases, the point of loss of LOS is very sensitive to the elevation of the observer, and so some or all of these four factors will interact to define the limiting distance. It would be difficult, if not impossible, to implement any kind of general solution to that problem without detailed datasets that just don't exist.

    That said, there are mapping programs that calculate visibility from specified locations and elevations due to simple topography, and so if buildings or vegetation are not the limiting factor, then those programs could be used to estimate necessary altitudes.
     
  6. alokbhargava

    Joined:
    Sep 28, 2015
    Messages:
    5,142
    Likes Received:
    1,658
    Location:
    San Francisco, CA
    Why do you need LOS if you are flying with Litchi? Litchi continues mission even if signal is lost.

    But anyway you can use following formula to calculate LOS for a known height:

    distance to horizon (miles) = sqrt [ 7 × h (feet) / 4 ].

    In ideal condition one can see up to 3.5 miles due to earths curvature. 7500' is just 1.42 miles.

    If you are flying at 200' and above, you should not have any problems at all.
     
    #6 alokbhargava, Apr 28, 2016
    Last edited: Apr 28, 2016
    wallix likes this.
  7. Zerone

    Joined:
    Jul 28, 2015
    Messages:
    140
    Likes Received:
    70
    Location:
    S.Wales, UK
    wallix likes this.
  8. wallix

    Joined:
    Jan 5, 2016
    Messages:
    74
    Likes Received:
    22
    Thanks! This helps a lot. I read that while Litchi continues after signal loss, it will lose any custom gimbal controls at that time. Is that not true? That's why I was asking. I didn't want to waste time trying to program any POI if it would all be rendered moot at signal loss.


    Sent from my iPhone using PhantomPilots mobile app
     
  9. Mark The Droner

    Joined:
    Aug 26, 2015
    Messages:
    3,998
    Likes Received:
    1,168
    Location:
    Brookeville, MD, USA
    400 ft is less than a 10th of a mile so this is a geometery problem (note I did not say "just a geometry problem" because I never did well in geometery)...

    X is something like (actually less than) 1, Y is something like 90 (9x10). What's the angle? I don't know but I bet it's less than 10 degrees.....

    But on the other hand we have the fact that radio waves actually do NOT travel in a straight line. They curve back down towards the surface of the earth just like a golf ball. So that is an advantage, but the question is, how quickly does it start to curve? Does it take 1000 miles, a 100 miles, 10 miles, 1 mile? I don't know. In fact, I don't know much.
     
  10. alokbhargava

    Joined:
    Sep 28, 2015
    Messages:
    5,142
    Likes Received:
    1,658
    Location:
    San Francisco, CA
    Yes if there is no signal, you can't maneuver manually. Also even if there is no video, you can't do much.
     
  11. wallix

    Joined:
    Jan 5, 2016
    Messages:
    74
    Likes Received:
    22
    Yes, I'm only doing this because I have another friend with a P4 who is also trying to make it to his house, too - but he's never heard of Litchi so he only makes it 2/3 there before it comes home. I want to beat him with my crusty old P3A.
     
  12. alokbhargava

    Joined:
    Sep 28, 2015
    Messages:
    5,142
    Likes Received:
    1,658
    Location:
    San Francisco, CA
    Competitive spirit is good to have but one should know the limits else you reach a point of no return.

    Design your experiment on a smaller scale first and slowly expand to know its limits. Best wishes.