So many spectrum rules are totally weird though: should they be interpreted per radio device? or per user?
What -apart from cost- prevents a user who wants more bandwidth from installing 10 devices in parallel and alternate each radio so none of the radios exceed their allowed transmit duty cycle?
Folks with badges knocking on the user’s door. It is pretty trivial to locate stationary signals.
As far as I know there's not actually anything particular to 2.4 GHz allowing higher throughput for LoRa than that the corresponding Semtech chip happens to support wider bandwidths. (I.e. no legal barrier.)
The tradeoff is less range due to lower link budget. Doubly so because 2.4 GHz has higher free-space path loss. You're not going to get outside your house with these speeds. The primary use (as stated in the original post) is likely through clear space with a directed antenna.
(The 2.4 GHz band is better suited to this use since you can use antennas with higher than 6 dBi gain. If my math is correct, anything higher than 11 dBi is a win even accounting for FSPL and the power derating the FCC imposes.)
(Aside, I am the author of that MeshCore ticket.)
Thanks for educating us!
The legal power limit in these bands is 1 W. If you spread that out over 500 kHz, that signal is weaker than background noise at any given frequency for anyone more than about a city block away. (Give or take many factors.)
But, if you compress that 1 W into, say, 12.5 kHz (typical for FM voice), your signal is now detectable (and will interfere with other, possibly licensed, users) at over 6 times the distance.
There are probably other factors. For example, it's not legally sufficient to simply reduce your power by a corresponding factor. I suspect it may simply be the FCC's goal to reduce conflict between users by mandating spread-spectrum technologies for unlicensed use.
Note also that 47 CFR 15.247(e) [1] gives a spectral power limit which corresponds approximately with the 1 W max / 500 kHz min specified in (b)(3) and (a)(2).
Final side note – https://docs.fcc.gov/public/attachments/FCC-02-151A1.pdf is interesting reading as to how the current form of 15.247 came to be. Specifically it changed the rule from specifically DSSS to digital modulation generally, which in turn allowed the transition from 802.11b (DSSS) to 802.11g (OFDM) on 2.4 GHz.
[1] https://www.ecfr.gov/current/title-47/part-15/section-15.247...
It's a mechanism to try to make the 900Mhz band more useful to uncoordinated users.
In the end, won't be used.
Thank you for the update.
I guess you have never encountered the anger and wrath of a retiree who's into ham radio and has the regulatory office on speed dial.
There are other countries in the world.
And there are also places where there is no electromagnetic policies (think about over the oceans).