Has anyone noticed a significant amount of EMI on the UHF band from their APM 2.5 board? Turning on my APM 2.5 board destroys my Dragonlink range test.
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Has anyone noticed a significant amount of EMI on the UHF band from their APM 2.5 board? Turning on my APM 2.5 board destroys my Dragonlink range test.
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I figured out another source of problems: the PWM outputs. Even with only servo extensions attached (no ESC), the wires put off a terrible amount of noise. I was able to reduce this noise by placing a capacitor between the signal and ground, but now the output is a RC transient, not a square wave.
Any ideas?
No, I don't have any spares.
A lot more bench testing tonight, shows a strong correlation between the time the APM has been on and the amount of EMI that it produces. It causes no issues at first, but after awhile, the dragonlink starts dropping packets (indicated by flashing link light). It's gets worse and worse until the packets loss is at a steady ~2Hz. When power is removed from the APM, the dragonlink immediately stops dropping packets.
Alright, here is what I have figured out so far. Powering the receiver from the APM board is a bad idea. I was not able to clean up the power supply enough to do that. However, I was able to run them off of the same battery using independent regulators. A 100uF capacitor cleaned up the rest of the noise left on the receiver PS line.
Heat also seems to play an important role in this. It appears that the APM board puts off more EMI as it heats up on the bench.
Do you have another APM and/or Rx you can test with?
No, there was no USB connected. I tried disconnecting everything including the minimosd and GPS. I even disconnected the power module and ran the APM from a 5V BEC. It was still dramatically reduced range.