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Comment by ChrisRR | Hacker News Reader

Because what if it's not? My first thought is that the HDMI is radiating and interfering with the wifi antenna.

As an embedded engineer, it was a hard lesson for me to learn that not all issues are software issues and the hardware may need to be investigated. This is especially true where there is different behaviour between units. You can't just assume that your 99% estimation (plucked out of thin air) is correct and discredit other potential explanations.

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> Because what if it's not?

Then, after you done ruling out the most likely and easiest explanation to test, you can then start exploring the remaining possibilities. Skipping to the more exotic explanations sounds more interesting but it's poor use of time if there's still low-hanging fruit out there.

maybe, with high frequency radios and improperly shielded cables and chips, the most likely scenario is RF interference?

Improper shielding is an assumption with no evidence as yet. I also mentioned that the ease of verifying the explanation should be a factor. Changing software is usually very easy.

It's so common that it's not an unlikely starting point. EMC is a major issue in high frequency electronics design and the raspberry pi had a history of having to redesign certain parts because of not having enough shielding.

I can find [1] on the subject which is quite interesting.

[1]: https://www.element14.com/community/people/PeteL/blog/2012/0...

There doesn't seem to be much info on compliance out there for Pi 4 which must have been significantly different w.r.t HDMI.

Absolutely, and this was before the Pi had built-in Wifi. The norms you have to comply for are immediately a lot stricter as your device falls into a different category (telecommunications devices).

https://twitter.com/assortedhackery/status/12000566338980290...

Evidence :P

wrapping tinfoil around an hdmi plug/cable isn't particularly hard either :) chips are harder but at least you rule out the cable. HDMI cables are ridiculously finicky if you've ever tried to get anything more than the lowest common denominator 1080p going on them.

I don't agree that wrapping foil is a great way to 100% rule that out as there is room for error. Using different cables/dongles would be better and they already tried that.

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