915
you are viewing a single comment's thread
view the rest of the comments
view the rest of the comments
this post was submitted on 09 Sep 2026
915 points (98.9% liked)
Privacy
51047 readers
417 users here now
A place to discuss privacy and freedom in the digital world.
Privacy has become a very important issue in modern society, with companies and governments constantly abusing their power, more and more people are waking up to the importance of digital privacy.
In this community everyone is welcome to post links and discuss topics related to privacy.
Some Rules
- Posting a link to a website containing tracking isn't great, if contents of the website are behind a paywall maybe copy them into the post
- Don't promote proprietary software
- Try to keep things on topic
- If you have a question, please try searching for previous discussions, maybe it has already been answered
- Reposts are fine, but should have at least a couple of weeks in between so that the post can reach a new audience
- Be nice :)
Related communities
much thanks to @gary_host_laptop for the logo design :)
founded 6 years ago
MODERATORS
...when have remote signals ever used microphones?
Not fully related, but early TV remotes used sound rather than IR. The buttons made a distinctive "click" noise, from a mechanical mechanism. The different clicks were detected in the TV and used as input.
Plus side, no batteries to deal with.
Down side, about as (un)reliable as you would expect.
That's wild. How did the TVs identify the distinctive sound? That seems like it would be a pretty interesting engineering trick.
I believe it was old school analogue electronics, but I'm speculating there.
I just looked it up, it was ultrasonic signals. The main one was the Zenith Space Command.
Cool, thanks! No problem. I understand it was analog electronics and using an ultrasonic signal makes sense, but what I wondered about was how did the receiving end (the TV) differentiate between the signals for the different buttons and then decide to execute different procedures based on that. Still pretty interesting in any case.
Speculating, but I would guess they applied a band pass filter to it. You can then either take a simple threshold value, or look for a rapid change and trigger off that. 4 buttons means 4 sets of filters, each tuned to a different frequency.
That said, the analogue electronics engineers of yesteryear were insanely competent and making analogue circuits do interesting things to save money or space.
Ah, yes, that makes sense, thanks! Totally agreed on those old school engineers being insanely competent and creative.
Randomly this appeared in my feed.
https://youtube.com/shorts/Qpyd7TsH14Y
Doesn't say anything about the receiver side, but shows the mechanism quite well.
Oh, awesome, thank you. Very interesting and very creative. No batteries!