Radio frequency interference reduction in Smoothieboard v2 series
Jason Frazier
Hi All, Arthur suggested I try here with my topic.
In Smoothieboard v1 5xc, there is significant radio interference emitted by the Ethernet circuit whenever there is a 100Mbps cable plugged in. The interference shows up as 460 Hz pairs of spurious HF RFI birdies, spread out about 61 kHz apart across the 14MHz spectrum (amateur radio 20 meter band) and beyond. My only workaround has been to limit Smoothieboard to running at 10Mbps (10base-T) speeds. The interference shows up on my shortwave radios, picked up by wire antennas hung in trees about a hundred feet away outdoors.
Since one of the selling points of Smoothieboard v2 is an upgraded network experience, you may wish to have your team evaluate emitted radio interference by Smoothieboard when plugged into 100baseT and 1000baseT, and ideally add sufficient filter components, grounding, and/or other remedies to reduce any emissions present in the V2 series of boards. It would be a fairly simple test:
- You could get a local ham radio operator to help you check, if that operator has a Software Defined Radio with waterfall display;
- Or you could buy a cheap RTL-SDR receiver kit and
check the board’s idle emissions yourself:
http://www.amazon.com/RTL-SDR-Blog-RTL2832U-Software-Defined/dp/B011HVUEME
You
won’t need a large antenna setup, the emissions can be picked up by pretty much
any antenna if you move it close to the Smoothieboard. Checking for other
emissions during actual printer/CNC use would be an awesome stretch, but for my
part I am mostly concerned about the never-ended 100baseT banshees that show up
in my radio shack. Of course, you would want to locate and turn off any
other sources of the same interference before you start with the device under
test.
I can certainly help with this testing, however I missed the notice about the V2 Kickstarter and seem to be out of luck in ordering a V2 board.
Cheers,
Jason Frazier