[breaking] fix EU433 LoRa definitions

[andrekir]

EN300220 ETSI V3.2.1 [Table B.1, Item H, p. 21]

[andrekir]

marking as draft since changing the start frequency will likely break backwards compatibility. other regions using 433.0f should also be reviewed.

[caveman99]

I am not sure this is necccessary, at least i recall similar discussions a while ago. Seems like ETSI specifies center frequencies with a bit of guard to allow for the bandwidth. The matching ITU allocations start and end at the band boundaries and Meshtastic takes that into account when calculating the center frequencies. Let's follow this up on #frequency-bands in discord.

[andrekir]

no rush, leaving as a reminder for the next breaking cycle.

considering convention and even EU_868, it's pretty safe to say 433,050 MHz to 434,790 MHz is the proper frequency range for EU_433.

[mc-hamster]

Good eye @andrekir !

[S5NC]

10 dBm ERP is 12.15 dBm EIRP, which form of radiated power are we using? If we assume a 0 dBi antenna, it should be the latter.

[fifieldt]

Q) How about offering EU_433_OLD and EU_433_NEW in parallel for a while? That way communities could choose to move independently of our firmware timing?

[andrekir]

on second look, the added 50 KHz represents about 0.0115% in frequency shift, which I suspect is well within tolerance for radios to interoperate using either center frequency. I don’t have any 433 MHz radios to test that theory, though.

[caveman99]

on second look, the added 50 KHz represents about 0.0115% in frequency shift, which I suspect is well within tolerance for radios to interoperate using either center frequency. I don’t have any 433 MHz radios to test that theory, though.

Right now we have 433.0-434.0 which is 1 MHz or 4 default channels. New definition is 433.050-434.790 which is 1.74 MHz being (almost) 7 default channels. I propose to change it to 433.0-434.8 with a margin of error ... :-) - the 50khz spacing is really a guard against the next band user below and the gauss tx distribution is weaker near the edge of the band. Also we're talking a few milliwatts here, it's not like this is the Chinese Firedragon Shortwave jammer ...