I had done the aluminum foil mod to protect my GPS signal strength. Never really had an issue, but after the mod, I found I acquired satellite lock faster and maintained higher readings.
This week, I received a new Flytrex 3G. The Flytrex has a cable that connects to the GPS wire coming from the puck at the top of the shell, then to the port on the main board, and finally with a pig-tail to the Flytrex unit. After installation of the Flytrex 3G unit, I noticed the satellite lock dropped significantly, and was more affected when recording. Even while flying, I'd drop below 6, when I had been getting about 9-12 satellites, even while recording.
I reread the posts in this forum. I figured the new interference was coming from the connecting wire that the flytrex uses. Once I removed the shell, I tried several different things.
- 1. Holding the shell above the unit to the length the wire would allow (about 7 inches) provided instant five satellites in my house.
2. Placing several more sheets of aluminum foil between the gps puck in the shell and the phantom also provided the same result.
With this information, I decided that aluminum foil, at the correct thickness (about 64layers), does provide excellent shielding. I wasn't using enough in my original shield and the new, longer wire needed to be shielded too. With trial and error, I created a shield thick enough to provide excellent in door satellite lock, then covered it with duct tape, tucked the Flytrex wires under it (leaving just enough length to connect to the board) and put the shell back on.
Bingo! With the thicker shield and wires tucked behind it, I got excellent satellite lock (as I had been used to), even while recording. I was concerned with the additional weight of such a thick shield, but it has not affected the flight characteristics in any detectable way. I also fly with the Flytrex 3G box and an ND/petal filter for the camera. The additional weight has had no detectable effect.
The P2V+ v3 has taken steps to mitigate this problem with ferric donuts, etc, but for v1 owners,
this foil mod is an absolute must.
- Losing GPS will cause the RTH function to fail, resulting in "flyaways".
Losing GPS at a good distance will cause the loss of IOC, course lock and home lock functions, making the bird respond as if IOC was off, confusing some pilots and resulting in "flyaway".
Losing GPS lock will cause the bird to switch to ATTI mode, and drifting with the wind (perhaps out of control range), and also causing "flyaways".
I believe DJI's poor design of the FC200 camera and the control board creates extreme RF interference that can easily result in loss of GPS signal, and subsequent loss of RTH, IOC, and GPS stabilization, with peak interference occurring during recording. With the use of copper or thick aluminum foil shielding, pilots can overcome this inherent design flaw and safely fly their birds.