RC Receiver interference from the autopilot board

[waiweng83]

Hi,

Currently I'm trying to build one UAV as my freetime project. But I have run into this problem which is blocking me to take the UAV for its maiden.

My configuration is as follow:
1 * dsPIC30F6014A for ppm decoding, stabilization and navigation control
1 * dsPIC30F4012 for servo pulse generation
1 * dsPIC30F4012 to extract the information from the GPS NMEA string.

The communication betweent the dsPIC is I2C.

The problem is if I power the RC receiver from the same battery as the autopilot, it will have a serious interference problem and shorten the range of the Rx. If I use a separate battery to power the Rx and opto-coupled the output from the Rx, the problem gets better, but still not completely gone.

I have tried to wrap the Rx and all the servo wires in the grounded aluminium foil but it doesn't help either. I can't move the Rx any further away from the autopilot as my compartment in the plane is limited.

Anybody have the similar experience that can advice me?

[Unterhausen]

seems like you should wrap the autopilot in aluminum foil.

[Jack Crossfire]

Usually the servos & motor interfere with receivers. The antenna has to be far away. May also be jitter in the PIC synthesized PWM that the stock receiver didn't generate. That makes the servos suck a lot more current. May not be the receiver at all but the PWM frequency being just out of range.

[waiweng83]

Usually the servos & motor interfere with receivers. The antenna has to be far away. May also be jitter in the PIC synthesized PWM that the stock receiver didn't generate. That makes the servos suck a lot more current. May not be the receiver at all but the PWM frequency being just out of range.


Did you mean that the pwm signal generated by the autopilot will interference with the Rx? If so, any idea how to solve it? There are a lot of ppl out there successfully implement their autopilot which share the same battery with the Rx. I wonder how they solve the interference problem. Any experience guy can help me???

[Jack Crossfire]

Motors use a lot of current. When they use current, they emit electromagnetic interference. The duty cycle in the PWM signal is a motor control so it directly controls how much current a motor uses and how much electromagnetic interference it creates. More specifically, changes in the duty cycle cause the motor to move. Hand coded PIC motor control can have lots of jitter. Jitter is slight changes in the duty cycle. This causes the motor to keep moving, consuming current, and generating interference.


People have lots of interference between autopilot & receiever. It's just not fun admitting your $3000 baby doesn't work.

[Crash Pilot]

waiweng83

I have the same problem. When I activate the autopilot my range goes from 100m with the arial down to about 2 meters. I have changed everything except for the receiver.

I suspect that my issue is with my JR 36mhz receiver. I have been waiting to finish a new project before I order another receiver to try.

Crash Pilot