Servo Jitter caused by Telemetry module

I’ve just finished the construction of my GoDiscover FPV foam wing from HobbyKing, with an ArduPlane controller. I ran into a serious jitter problem with my analog gimbal servos (your basic Tower Pro 9g micro servo). They are jittering all over the place (the video is linked).

The jitter is synchronized with the telemetry module red LED (i.e. transmissions) so I guess the module must be noisy enough to disrupt the servo signal.

I checked around this site and the web, and there was a suggestion that the telemetry unit for the APM 2.6 was causing this problem in a number of builds. Absolutely yes… see the videos linked. When I unplug the telemetry unit, the servos stop jittering.

As a solution, I may try wrapping the module in grounded aluminium foil (per one suggestion) or maybe just forego stabilization and plug my servos into the FrSky Delta8 receiver directly. I’d rather have telemetry than stable gimbals.

I’m not sure why there is such a pronounced effect from the telemetry unit, but my conclusion is that you shouldn’t be using an analog servo-based gimbal with this setup (at least not plugged into the APM 2.6).

I’m going to look around for solutions (maybe digital servos don’t have the same problem … I’m going to give them a try today), and maybe grounded foil around the telemetry device will work (then, a little too ‘alien mind control’ for my thinking). I’m not sure that stabilization with a Sony HD 700TVL cam (which is what I like to use for FPV) is really a must.

More pictures of servo jitter caused by telemetry module. I wonder if this would be a problem with the elevon control surfaces as well … we’ll soon find out. Here you can see the front of the plane, and the transmitter-FPV unit (video).

Servo Jitter occurs even when connected to Rx module (see attached video). It doesn’t seem to be any less, so whatever noise the telemetry unit is putting out affects everything. Particularly unsettling is that I have EMAX ES08MD 12g/ 2.4kg Mini Metal Gear Digital Servos in both elevons, and these jitter as well with telemetry (although not much; they are far away from the module … I don’t know how much impact being digital has).

Still having problems?

I had jitter in 9g analog servos with a 3DR Telemetry radio. I could prevent the jitter with a foil panel, but a better solution was changing the telemetry radio output. I turned the on board transceiver tx power down from 100 to about 11. Good range for LOS operation. Good luck!