I am a quadcopter head, DJI Inspire I is my favourite. But my flying got big touble from those UAV defenders or drone jammers. I can not control my copter with remote control pad, some signals are blocking the transmittions. I checked around, there was a guy took a gun shape weapon with two antennas, something like a drone jammer or UAV defender . That is a crass situation who developed these kinds of gadgets which can out-off-air normal quadcopters. Try some questions on these gadgets of UAV defender or Drone jammer , 1)do they block 2.4GHZ, 5.8GHZ and GNSS? 2) can they cut off quadcopter's signal within 2-3km? 3)are they possible to take over the control pad of auadcopters? I do desire to know how the uav defender (www.uav-defender.com) works? how to readdress the current crass situation?