vive pro 2 Vive Pro 2 and sim racing EMC challenges

[JJD]

Warning this post include technical jargon and its imbued with engineering spite.😈

 

With my unit there is an EMC problem when using DD wheel base.
And I mean IS not maybe nor seems to be or etc. There is and EMC issue.

Dictionary:

• DD = Direct drive
• EMC = electromagnetic compatibility
• DoC = Declaration of conformity

Setup

• Moza R5 DD bundle with pedals and clutch
• Moza HGP Shifter USB
• Moza HBP handbrake USB
• Next Level Racing Wheel Stand (Where all racing  sim gear is attached)
• HTC Vive Pro 2 VR headset
• HTC Vive Base Station 2.0 (up high on a tripod)
• Windows PC metal case.
• Wall sockets have earth

TL:DR:

Shortly about the problem: the HTC start to blink to full grey screen semi frequently depending on the distance and few other factors.
But sometimes it feels that the blinking is depending on the sun and moon phases. But the main factor is distance from the DD and it is very reproducible.
Sadly the distance from the seat to the DD is not just far enough.
This only happens IF the HTC is close to DD or the DD is shutdown. Makes rallying quite annoying.
Pimax 5k Plus and Pico 4 works flawlessly with the system.

Longer story if interested ->

Debugging

Total time done debugging is a quite some time..
But I have tried different positions for the base station with no effect (longer distance, higher, lower, different location).
I tried different ferrites on the the headset cable, DD cables. Seemingly no visible effect. Also, hard to guess the correct ferrite when you do not know the frequency. Hence tried several different ferrites ranging from 10MHz to 1GHz.
After that I decided to do actual measuring with just DMM (cause only have DMMs and shitty oscilloscope at home). Tho, I did some interesting findings:
- With the rig and PC case there was around 8Vac which isn't great and the HBP has from USB housing to case 100 kohms, while shifter and DD are isolated. This was interesting find.
-- Hence tried next earthing the rig from DD connection bolt to the PC case.
--- This was rather nice success -> the HTC became less prone to blinking but yet faar from perfect.
Next investigated the handbrake as the 100kohm was quite curious -> Removing the USB cable from the handbrake actually makes the VR headset usable while rallying or driving.
Buut it is not interference free: Meaning taking hand too close too the headset makes it blink again. Well can race with this buut I'm missing my handbrake. Rather sucks.
So, was wondering about the earthing and taped the USB connecting to the handbrake with electrical tape so it doesn't earth. Well interesting it got better, kinda.
Still more prone to blinking than without the USB cable.

Anyways new finding after shower:
Was doing some more debugging after shower and when touching the rig with wetish and bear feet the blinking comes.
Hence some coupling through my body happen?
Not 100% didn't have the proper engineering energy to engage the debugging and was like "feet touch -> blinking" interesting.
Tho, I did kinda guess something like this before.

Where the problem

Well, if I would be a betting man I would bet on the HTC.
Why? Well Pimax works flawlessly and so does the Pico 4 (tho. Pico 4 is standalone and tracking is different).
Also, as industrial engineer I would bet that HTC engineering team has seen this effect themselves ofc. they will never disclose this.
Even tho HTC has a proper DoC where there is the EMC standard they tested it against and it should be more than OK with household electronics (tho could be some trickery there which is not public knowledge, but stuff like that technically should be on spec sheet).
Just speculating here but there was a huge component shortage which made several manufacturers jump to different ships and etc. and in a hurry did HTC re-test EMC?
Reminder that this is pure speculation. But I have seen that happen where I work.

Now technically still possible that it is Mozas fault not impossible but I think improbable for reason:
- Pico and Pimax works fine which would mean that they have went over normal household electronics specs in EMC and not just by little.

Now this seems to be a rather technical problem and I'm pretty sure this won't be solved here.
Buut perhaps someone else had similar problems or etc.

Anyways my little investigation started as little side project but now after all blood and tears. I think this post is more about venting and spreading the word.
Ou yeah in case wasn't clear HTC works flawlessly with out the DD.
Aand yes I have been in contact with HTC and Moza since last ~December. Buut as this is technical case normal support just won't cut it.