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Is copper shielding effecting gps lock

Discussion in 'General Discussion' started by Seedler, Apr 27, 2014.

  1. Seedler

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    Hi guys,

    Still having gps issues. From my previous posts, I didn't replace gps antenna cos I didn't find any cracks and I was afraid of destroying something by upgrading to a larger antenna.

    Anyhow I have another idea for the cause of my problem. Could the copper shielding under the gps module be blocking satellite signals?

    My problem was I was loosing gps signal while flying. I've only noticed that while flying in one direction I'm getting 9 satellites, but flying in the opposite direction I'm only getting 5 and loosing gps lock. This could be while pitching in one direction the copper could be blocking out a good 45 degree of the sky. Does this sound like it could be right?

    Is it only the gps module that needs shielded or the module and antenna both?

    I have noticed that the copper shielding is stuck to the bottom of the module, but is also tucked in around it. Should I loosed this up a bit?

    Is there any other way to stop interference like ferrite rings, or other forms of shielding that would not block signals to gps?

    Thanks again everyone,

    Dee
     
  2. Seedler

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    What about the gps module battery. Could this be the cause of my problems as well?

    Thanks.

    Dee
     
  3. Dalite

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    Location:
    Brunswick, GA. USA
    I would not recommend altering the GPS board.

    I am assuming you are flying a Phantom. If not, much of the following won't apply.

    Is your shell painted, or do you have any decals on the top above where the GPS board is mounted?

    Any directional control given by the pilot causes a tipping of the phantom as the appropriate motors are slowed and the others increased. Flying GPS Into the wind may case a tilt at hover. Any tilt can change the view to the sky. The GPS antenna does a great job; on the ground and in level flight it has the advantage of the largest field of view.

    If you are using a GoPro and a Gimbal, you have 2 other devices that could be a part of the solution. The GoPro makes a considerable amount of electrical hash without wifi being a part of the mix. The gimbal can concentrate that noise as it moves the camera. If you do use a GoPro, remove it from the mount, remove your props, get GPS lock, then power up the GoPro close to the top and see how many red lights you get. Move it away, get GPS lock again, and place the GoPro close to each leg, front back and along the underside to see if you lose lock. Finally , remount the GoPro, get sat lock and move the GoPro in the travel area that the gimbal provides and see if you get any red lights. Finally, fly without the camera or any other add-ons powered up and see how the GPS behaves.

    The battery is designed to only store the GPS location where it was last used in the module's memory. It helps the start up time when flying in the same basic location. It is not in use when the flight battery is connected.

    On the Phantom GPS board, it is not a user serviceable item, unless the person attempting to replace it has the eyesight, tools and soldering experience to do the job. You have to use enough heat to melt the bond to the metal cage surrounding the battery without causing damage to adjacent surface mount components. It is a delicate balance to achieve if you don't do that kind of work often.

    I hope others can provide better suggestions, based on more experience. I have only been around the Phantom around 3 months and I am learning more each time I fly.
     
  4. Seedler

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    Hi Dalite, Thanks for the reply.

    I don't have a gopro or gimbal. I do have a fatshark transmitter and pilotHD camera + iosd fitted to my phantom 1.1.1.

    Thing is I was having the problem of finding it difficult to get lock before I added these items.

    I always fly from the same location, but it still takes sometimes 5 minutes to get 6 satellites. This makes me think the gps battery is dead.

    It still baffles me why most times my car satnav and a tomtom I have both can usually get 10 or 11 satellites, while my phantom struggles to get 7 from the same location.

    I don't know what to do,

    Cheers
     
  5. ianwood

    ianwood Taco Wrangler
    Staff Member

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    Sounds like your GPS unit is faulty. If you can get 10 svns on another device at the same time with the same view of the sky and you don't get the same on the Phantom, something is wrong with it. Time to fix (not lock) is based on where and when you last used it. If you used it in the past 24 hours in roughly the same location with the same view of the sky, the ephemeris and almanac data should still be usable so each satellite should be acquired pretty quickly.
     
  6. Seedler

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    Just did a test of the battery on the gps module. It read 0.8 volts. When flight battery is plugged in it charges the battery at just over 3.2 volts. I let it charge up and at the minute I'm timing how long it takes to discharge to 1.8 volts. I read that this is the minimum voltage the battery has to be to store ephemeris and almanac data.

    Do you think this dud battery could be the route of all my problems?

    Does anyone know the spec of this battery, and what my chances of a successful replacement are?

    Thanks.
     
  7. Seedler

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    Quick update. Just hit 1.8 volts after 17 minutes, and still dropping fast.

    Dead as a door nail :)