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by mikewarot 1008 days ago
Here's a fringe opinion you likely haven't heard before.

I think that small quantities of continuous RF really aren't a problem.[1] I think it's the rapid edges of packets that are the problem. The envelope of a modern TDMA/CDMA signal, as a series of packets, creates a little heating, then none, then a little heating... this is true for bluetooth, cell phones, WiFi, etc. Sometimes you'll hear the packets in your speakers, if you get some rectification of the signal because they're too close to your WiFi access point, for example.

In the end, it's making an audio frequency noise, albeit very small, that likely causes the most issues. I suspect those little ripples disrupt things, just a bit.

I've not seen any studies that go in pursuit of this tangent of thinking. I'm totally willing to admit I could be wrong. But in this modern era of lost institutional trust, I can't be sure.

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[1] After all, we ham radio operators used to walk around with 5 watt output (or more) handy talkies, right next to our heads all the time. The power levels these days are tiny compared to that.

1 comments

TDMA is long gone, and there are no "edges of packets" as you imagine them. I am not an expert, I only have little experience and knowledge from working in the area, but for example a few symbols are transmitted together using carriers at different phases. Those audio noises used to exist in the GSM area but no longer in 3G and 4G.
It took a lot of Wikipedia reading, but I finally got to OFDMA[1], which apparently is used by my 4G phone to talk to the world. I had no idea it just kept spewing RF at all times. Though, it will be transmitting more or less signal depending on how many subchannels it is using.

There will be experiments with an RF sniffer later when I get to my friends repair shop.

[1] https://en.wikipedia.org/wiki/Orthogonal_frequency-division_...

It also has simple power control, making sure that all phones are received at the same power on the receiving antenna. Overall OFDMA is magic, if you can put your hands on a spectrum analyzer with constellation diagram you will be amazed.