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Line of sight and range.

Discussion in 'General Discussion' started by rmb, Jun 7, 2016.

  1. rmb

    rmb

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    I fly both an Inspire 1 and a Phantom 4 and I don't know if the answer is dramatically different for each, but here it goes.

    I see a lot of videos where people are taking off in a wooded back yard and flying great distances. I have always been concerned about flying that way based on line of sight, safety and much decreased range. As a result I am forced to continue to increase altitude as the bird goes down range so as to keep in sight. The problem is that the closer you are to the tree line the distance you can go is increasingly diminished. I was wondering if someone could shed a little light on that topic for me. I have attached a crude sketch incase I am not being clear.

    los.jpg
    Thanks in advance



    rb
     
  2. SanCap

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    Some people don't care about seeing their copter. They just watch it on their tablet.
     
  3. rmb

    rmb

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    Any thoughts on how the deeply obstructed view (through 100s of yards of forest) affects range?
     
  4. SanCap

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    I don't have any numbers on that but I always have a clear line of sight when flying. Anything that goes between the copter and transmitter will degrade the transmission.
     
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  5. go fast

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    You would probably need better than stock antennas at that point...
     
  6. MarkLincs

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    Inspire will do 2km easily in a non RF noise area

    I'd expect maybe 4km Max on basic antennas
     
  7. Scotflieger

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    It depends where you are operating. In UK normal users are not permitted to operate Beyond VLOS (BVLOS). Our limits are 500m distance or VLOS (whichever is less) and maximum altitude of 120m (400ft). Yes, the aircraft can occasionally disappear behind a tree but that would be breaking the rules.

    The other issue would be loss of signal due to any building or trees (especially if wet). In such cases it is important that you have the RTH on Loss of Signal set and the return height high enough to avoid hit anything on the return path. Too many have lost aircraft by not working through the implication of flying behind a building, cliff or forest.
     
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  8. go fast

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    Thru woods/trees ?
     
  9. MarkLincs

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    If your above them yes at a decent height yes
     
  10. MarkLincs

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    Only solid objects or solid land will massively reduce the signal so never fly low down into say a trench / valley out of sight and your stood say 50meters from the edge of the trench / valley range will be drastically reduced.
     
  11. The Editor

    The Editor Moderator
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    To clear this up.......
    There is absolutely no straight answer as to how range will be affected.
    RF propagation is not an exact science and subject to many many variables.
    These can include:
    • Atmospheric temperature
    • Terrain composition
    • Density of forest
    • Water content of the trees! (Yes really)
    • Nearby valleys/canyons
    • Multipath interference/reflection
    • Isotropic propagation
    • Free space path loss
    • Frequency/wavelength signal
    • Polarisation
    • Phase shift
    • Other factors!
    So you see, there are just too many variables to give a precise answer to how far or how deep a signal will penetrate.
    If you stood at the same point and took off you would get different results on different days and even different results at differing times on the same day!

    2.4 GHz is basically line of site and has poor penetration and should be treated as such.
     
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  12. SanCap

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    That is exactly what I was thinking but could not put it into words :)
     
  13. MarkLincs

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    2.4ghz is LOS range.. you know you'll hear that a lot…

    you can go a LOT further than people think

    2KM is easily possible with a standard Radio control Transmitter say a Futaba 8FG / 14SG / 12FG will get you there or a Trannis will get you around 4KM. Line of Sight is the important bit don't let anything get between you and the aircraft. Height helps as well so your better off at 1KM and 400ft than 1KM and 10ft off the deck.

    The Inspire Will do 2KM easily enough in open spaces.

    The fact is to fly inside Rules were not meant to do any of that stuff.

    so 500m range it is for legal work and to be honest you don't need to go further most stuff is done within 50m or 75m of where your stood.

    I've flown RC jets and staying inside 500m you know what I bet I was going further than 500m and i'd never of known at all and at 180mph you cover that 500m very very quickly :)

    I've also had Thermal gliders up a good distance LOS and their dots in the sky :)

    The channel hopping helps and in built up areas even I'm wary of whats going on. We used to fly at club site that we always got a glitch on one side of the flight line. didn't matter which way you flew at a certain height and the same spot you always glitched. Microwave link right through the flying area, you just get used to it :)


    Range 2KM possible but don't do it, fly safe :)
     
  14. MarkLincs

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    So here you go

    7KM


    3KM


    1.6KM


    So there are vast differences in what people are getting with the inspire
     
  15. The Editor

    The Editor Moderator
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    These were done on differing firmware before the EIRP was changed as well as the encryption protocols.
     
  16. MarkLincs

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    And?

    It just goes to show what is possible with the right firmware and 2.4ghz

    You can rewind it all if you really wanted to or even find an older machine that's not been updated.

    But even if 7KM is no longer possible you can still go further than people think.

    Question is range

    Well it's generally more than 500m then is the answer - in an open area -
     
  17. licensed pilot

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    If one can't afford to replace your bird, then common sense dictates to always fly VLOS...
     
  18. Steve@AerialImagesPro

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    The whole point of not flying beyond LOS is not because of signal loss, its in case something goes wrong with FPV and GPS etc.

    Its about maintaining full control of aircraft at all times, or minimizing the out of control times.

    This brings us to why there are sooo many issues with drones as opposed to RC planes and helis. When something goes wrong with a drone most people have no clue how to really fly manually and land safely or bring it home in one piece.
     
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  19. licensed pilot

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    Bingo, plus there's no good reason to fly BLOS...
     
  20. rmb

    rmb

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    Thanks for your ivput. Speaking of firmware, I am more of a believer in "if it ain't broke don't fix it" than always staying current. I am also always afraid that a firmware update might remove features or restrict flight areas more, have bugs, etc. As a result I haven't updated in almost a year. What's your 2 cents on the best firmware version for the inspire 1?
     
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