I am using a 5V borescope analog camera (Sony CCD, PAL/NTSC) for visualization purposes. This camera has a 20 meter 4 core wire, which transmits power and video signal to and from the camera. Along with this, I am using a servo motor (Siemens V90, takes 3 phase 415V AC) which moves pulls and pushes the 20 m wire (in turn moves the camera inside a pipe).
Problem: The image fed by the camera has lot of noise. I could make out that, the noise disappears when the servo motor and driver is switched off. Since the motor takes 415V and the camera is operating at 5 V DC, there is a signal interference.
Can you suggest any possible solutions to avoid the noise in the image?
Note: I have added the wiring drawing of the camera and the TV that displays the live video from the camera. The green circle is the 4 core wire I m using (one unused wire). Please let me know if more information is required about the servo drive/motor and camera.
The below image shows the noise appearing in the screen
Best Answer
Try a common-mode filter on your camera cable to reduce the aggressor noise. Test a clamp-on ferrite bead to start with.
Try to route the servomotor wiring in pairs that cancel each other.
Make sure that there is no ground loop from the motor sneaking back through another path: isolate its return.
Apply filter caps across the motor phases to reduce transients / ringing. (Make sure the caps are rated for this.)
Look for ways to control the spectrum of the motor drive signal (e.g., reduce slew rate, filter PWM hash better, etc.)