this post was submitted on 16 Mar 2024
1570 points (98.0% liked)
memes
10673 readers
2670 users here now
Community rules
1. Be civil
No trolling, bigotry or other insulting / annoying behaviour
2. No politics
This is non-politics community. For political memes please go to [email protected]
3. No recent reposts
Check for reposts when posting a meme, you can only repost after 1 month
4. No bots
No bots without the express approval of the mods or the admins
5. No Spam/Ads
No advertisements or spam. This is an instance rule and the only way to live.
Sister communities
- [email protected] : Star Trek memes, chat and shitposts
- [email protected] : Lemmy Shitposts, anything and everything goes.
- [email protected] : Linux themed memes
- [email protected] : for those who love comic stories.
founded 2 years ago
MODERATORS
you are viewing a single comment's thread
view the rest of the comments
view the rest of the comments
Oh no, I get why the interference happens, it's more the content of the interference that surprises me. With analog video, a white screen is basically a 15 kHZ full amplitude square wave, but HDMI is encoded so regardless of the balance of 0s and 1s in the original content, the data stream should be just noise either way.
You mentioned powered speakers plugged into it, which means the output from the display is unamplified, and it is amplified by the speakers. So the wiring from the DAC, decoding the HDMI signal to the jack where the speaker is connected is analog and surrounded by very noisy digital circuits, especially power circuits, which induces the noise.
Most digital speaker systems, such as Bluetooth headphones have a single IC for both DAC and amp which effectively eliminates any induction of noise.
The weakest point in the audio system is the unamplified analog signal. Any induced noise is amplified with the intended signal.
The frequency heard is going to be a function of what signal is causing the induced noise. Depending on the display, it could be any number of subsystems. Usually related to the backlight, but not always. The noise is very likely completely unrelated to the audio being played.