Where are my satellites?

Discussion in 'OnBoard Electronics & Controls' started by Velsia, Jul 8, 2020.

  1. Velsia
    Joined: Oct 2008
    Posts: 79
    Likes: 5, Points: 8, Legacy Rep: 15
    Location: Jersey C.I

    Velsia Floater

    I have heard that GPS receivers should not be placed high up as they suffer from the oscillations of the boats movement and often you see these on push-pits etc.

    Is this also true of satellite communication domes as I have seen these both on deck level and on the spreaders?
     
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  2. CocoonCruisers
    Joined: Dec 2015
    Posts: 62
    Likes: 17, Points: 8, Legacy Rep: 10
    Location: Marseille & BuenosAires

    CocoonCruisers Junior Member

    GPS beeing quite responsive, the problem is that the accelerations high up the mast would tend to result in technically correct speed and heading data showing with great precision ... what you masthead does at the moment of measurement. In a seaway, that can be quite different from what you actually want to know: where your hull is headed.

    As far as i understand, sat com equipment should not suffer from high mounting: to fixed antennas the motion is irrelevant (this stuff works well on jetplanes), and for a tracker dish, the angles remain the same. Just make sure the rig can handle the accelerations physically, and that your boat can stand the weight so high up.
     
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  3. jehardiman
    Joined: Aug 2004
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    Location: Port Orchard, Washington, USA

    jehardiman Senior Member

    CC covers most of the bases for receivers; however, mounting a tracking receiver higher causes higher loads on the antenna tracking gear (i.e the stuff that keeps the antenna pointed at the satellite) so it should be avoided mounting them too high. Additionally, for a tracking receiver, it should have a good view of the sky so you don't have dead spots, and all receivers should not be mounted "close" to structures to prevent double pathing. To calculate loads on mounted antennas, see MIL-STD 1399, Section 301a, for the formulas.
     
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  4. Velsia
    Joined: Oct 2008
    Posts: 79
    Likes: 5, Points: 8, Legacy Rep: 15
    Location: Jersey C.I

    Velsia Floater

    The knowledge contained within these forums never fails to amaze me. Thanks for your help guys.
     
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