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  • Hacker News
  • Previously [2023]: https://news.ycombinator.com/item?id=35882967
    by mytailorisrich
  • I think there’s some real value in WANs that are independent of both the internet and existing telco infrastructure but I don’t think I would put a specific transport at the centre of its design. I think you would be much better off with something like bundle protocol v7 and delay tolerant networking as the actual centrepiece and have something like LoRa as one of many transport link options.

    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.

    by mdhb
  • I tried doing something like this on an ESP32 last year, I wanted to understand how to do an actual mesh with devices that can't transmit and receive at the same time, but I didn't find documentation.

    I managed to get 2 devices communicating across town at least ! (After having antenna issues)

    by LelouBil
  • Chat/text over LoRa always sounded intriguing! I'm merely a 1000km away from Sicily (which antirez say they wanna cover with the network at first), I wonder if it would be possible to do what AM radio does, bounce against the ionosphere and get huge ranges for transmission? Maybe it would need way too much transmission power? Maybe hopping all the way P2P style makes more sense, although surely would be slower.
    by embedding-shape
  • Unlikely since the most ISM bands are UHF (EU is 868 MHz) and skywave propagation (what you’re referring to) is characteristic of HF radiation (3-30MHz). VHF/UHF radiation passes through the ionosphere instead of refracting.
    by amingilani
  • Not at 900MHz. Skywave propagation mode is only available under about 30MHz. Above that, the signal reliably continues on into space.

    At frequencies this high, you’re realistically limited to near line of sight paths.

    by bigfatkitten
  • Checkout MeshCore; we're doing 400 miles using 12 hops going from north Vancouver to Eugene Oregon https://analyzer.letsme.sh/map?lat=47.36113&long=-122.20419&...
    by mikeytown2
  • > Simple home-made driver for the SX1276 and SX1262 LoRa chip

    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.

    by exabrial
  • The chip itself supports using a TCXO instead of a regular crystal
    by oakwhiz
  • This is a radio module issue, not a chip issue.

    Cheap modules have cheap crystals, better ones have a TCXO.

    by bigfatkitten
  • You mean they don't have temperature compensated? What you described is temperature dependent
    by Neywiny
  • Temperature Compensated Crystal Oscillators (TCXOs) is what they should be looking for. And to be clear you can get SX1262 variants with such, eg: https://wiki.seeedstudio.com/wio_sx1262/

    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.

    by ShakataGaNai