Recently I’ve been dealing with some phantom drop outs of force feedback and inputs from my wheel base along with ghost inputs from my DIY button box. The wheel would go limp for a moment, and no inputs would register during that time. The game would continue with whatever input it last saw, which is a Bad Time™ when you’re heading full speed into turn one at Monza…
At first, I thought this was a fault in the wheel base – but after asking around on the SimHub Discord it was suggested that what I was experiencing was likely due to electromagnetic interference, EMI for short. This was also a much more likely explanation as I’ve recently added both motion and a wind sim to the rig, meaning more cables running near one another that could exacerbate the issue.
Initial troubleshooting
The easiest things to try out of the gate, is to unplug the latest parts you’ve added to your rig and see if the problems still present themselves. For me, this meant turning off the motion platform and wind sim and then testing the rig in anger to see if the problem was still there. Thankfully, it appeared to have resolved the problem – so it was on to working out how to fix it.
The sole developer of SimHub also has a vast knowledge base covering not just SimHub related topics, but also other findings – such as this great information about troubleshooting USB issues that gave me the following points to try.
Moving wires
Sometimes, EMI is caused by nothing more than your wires being too close to whatever is putting out the interference. This can be a USB cable running near a strong motor such as those used in motion platforms but also possible that power cables running parallel to USB leads are the perpetrator.
I should have thought about the fact that power lines were running perpendicular to data lines earlier than I did. I had a stereo installed in my car many years ago which the “professional” installers ran both power and audio cables down the same side, leading to an audible interference through the speakers. They told me I needed a suppressor for my alternator – and that they wouldn’t move the cables. That ended up with me redoing their work (and learning a lot in the process about getting wires around a car) to move the audio wires down the other side – hey presto, interference gone.
Ferrite cores
Another common solution is to apply ferrite cores to the USB wires that connect your devices. These can filter out any unwanted noise that may be travelling through the cable from interference. I opted to go for a pack of clip-on cores that meant I could easily place them on wires that had already been managed around my rig in various places.
So far, these have had the desired effect in that the wheel base no longer drops force feedback or loses inputs randomly during driving. So my fellow racers on track needn’t fear me barrelling head first for them into the corkscrew at Laguna Seca…
What next?
My journey isn’t over yet – my DIY button box still appears to be having some form of ghost inputs, which I believe may be one of two tangential issues:
- The USB hub that I’m using on the rig, despite having a power supply, cannot handle the demand being placed on it any more.
- There’s a floating ground issue somewhere, that’s causing those inputs.
When I’ve worked out what’s going on there, I’ll be back with a follow up…
Update 14/07/2025
Doesn’t appear that the ferrite cores did the trick, I was merely blessed by RNG at the time for it not to happen during my initial testing phase. Though I’m still keeping the cores on the cables for the added peace of mind. See part 2 for my ongoing testing…
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