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Comment by scrps | Hacker News Reader

Must have been a poorly made jammer or multiple jammers. 5G is sub 6GHz, LTE is sub 4GHz and for Santa Clara county almost all public service and trunked radio systems are sub 1GHz (radioreference has most of the frequencies between 300MHz+ and 900MHz) so whoever had this jammer running was jamming one hell of a wide swath of the RF spectrum. As you said they were putting out way more RF to jam all that than 5G uses.

Edit note: misread article, states "They found two signal jammers"

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LTE and 5G sometimes operates pretty close to public safety, for example the 600 and 700 MHz (sometimes referred to as low-band LTE/5G although that's a bit confusing given low band is more often used to refer to low VHF and these are low UHF) are close to the 700MHz public safety bands. There's a similar issue around 900MHz.

And a lot of public safety radio these days is LTE - most cities operate an LTE network on one of the upper public safety bands, and they see extensive use by police and fire for MDTs. Voice is still more often over something like P25 but frequently adjacent to municipal LTE. So even a well-designed LTE/5G jammer might target these bands.

But in general jammers are not precise devices. 5G operates over many bands in a few significantly different parts of the radio spectrum. It's by far easier to emit broadband noise in the right general regions, but that will end up knocking out hundred-MHz wide swaths or more.

> 5G is sub 6GHz

Quick google search suggests otherwise. It appears to depend on configuration but can go over 50 GHz, is that true? Would be a real broad band operation if they're trying to jam all that.

I can't speak to the intentions of the person operating the jammer - if a person were using a jammer believing it to be prophylactic of the effects of radiation by 5G radios it may not be useful to ask what frequencies they were trying to jam.

Anyways, the excerpts from DDG results for the BG-E8 5G list its jamming spectrum as 870MHz to 5850MHz. And for probably 98+% of users that will cover the frequencies in use where they live. The "high band" frequencies (25-100GHz) have a much shorter range, very low penetrating power (essentially you need to have line of sight to the antenna), and really only make sense in very high density areas like stadiums and maybe urban cores.

Thank you, I stand corrected. It seems 5G is all over the spectrum according to the FCC[0]. Not quite sure why I thought it was limited to sub 6GHz for some reason.

[O]: https://www.fcc.gov/5G

Probably because sub6 is the only one that matters to most people. The others are rather useless outside of high density events(think a football stadium and such), as they have next to zero penetration power.

Most 5G phones only supports “sub6” and only few supports “mmWave” standards. These are sort of analogous to “2.4GHz” and “5GHz” in Wi-Fi.

Yes, 5G can operate on lots of different frequencies depending on whether you want high bandwidth or high coverage (or, through careful combinations) both!

Since 50GHz is basically line-of-sight, if you want to jam it, just build a wall!

You can buy products online which claim to jam just about everything. For "testing" purposes of course.

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