I managed to get 2 devices communicating across town at least ! (After having antenna issues)
At frequencies this high, you’re realistically limited to near line of sight paths.
Shame, but at least now I understand why, thanks :)
> you’re realistically limited to near line of sight paths
Wonder exactly how far one would be able to get up to reach 1,000km line of sight, assuming you put both points equally far up. Guessing it's the curvature of the earth that gets in the way at that distance?
[0] https://www.hackster.io/news/fossasat-1-an-open-source-satel...
This is just too crazy, thanks a lot for sharing these links! :)
What's the E2E latency on that, for curiosities sake :)
I can't wait for us to somehow figure out how to connect all the various mesh-networks in the world. MeshCore is a whole continent and ocean(s) away from say Freifunk or Guifi, but would be incredible if we could figure out how to interconnect between them, so we could all talk via the already built alt-infra. Maybe the FossaSat mentioned in another comment (https://news.ycombinator.com/item?id=45806794) could finally be one option.
If you're looking for parts the Diamond BC920 is the best antenna. Station G2 with a $100 3-4mhz cavity filter for each frequency as well.
Maybe we are talking about a different threat model here but LoRa as the centrepiece falls apart really quickly the moment someone somewhere decides they don’t want your WAN to exist anymore.
exabrial•3mo ago
Beware of what nailed the Meshtastic people: These chips don't have temperature dependent crystal oscillators. Transmitting more than a few milliseconds causing a temperature rise, throwing the clock off, causing transmission warpage, causing timing errors, causing transmission failures.
Neywiny•3mo ago
exabrial•3mo ago
bigfatkitten•3mo ago
Cheap modules have cheap crystals, better ones have a TCXO.
ShakataGaNai•3mo ago
For the detailed run down, see https://cdn.sparkfun.com/assets/f/f/b/4/2/SX1262_AN-Recommen... page 14
> In the case of an SX1262 operating at +22 dBm in the US 902 – 928 MHz band, the frequency drift measured during the maximum LoRAWAN™ packet duration stays below the maximum limit, provided thermal insulation is implemented around the crystal during PCB design.
> At extreme temperatures (below -20 °C and above 70 °C), it is recommended to use a TCXO.
> For any other frequency bands corresponding to longer RF packet transmissions at +22 dBm, it is recommended to use a TCXO.
buckle8017•3mo ago
As used in the meshtastic devices this chip does actually fail doing normal Lora transmission under reasonable conditions.
I know because I've seen the exact failure.
nerdsniper•3mo ago
oakwhiz•3mo ago