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May 2025 - ShortFast Trial/Experiment

For the month of May we are encouraging the local Meshtastic community to switch their nodes from the default LongFast channel on the LONG_FAST modem preset, to ShortFast on the SHORT_FAST modem preset. Switching your node to SHORT_FAST should automatically update your default channel 0 slot from LongFast to ShortFast (same key) but not all nodes and versions do.

Why?

Why are we conducting this experiment? There are several reasons we want to try out a non-default mesh in the Puget Sound area, and also reasons for it to be on ShortFast vs staying on LongFast.

There is a recent Meshtastic Blog post that is very relevant: "Is LongFast Holding Your Mesh Back? Better LoRa Presets for Bigger Meshtastic Networks"

  • Legacy nodes, and unreachable ROUTER mode node owners.

    • Meshtastic works best when there are a minimal number of ROUTER mode nodes, and their placement is considerate of all other ROUTER mode nodes.
    • There are a large number of nodes (many dozen) in our area that are set to ROUTER, ROUTER_LATE, or ROUTER_CLIENT and are not reachable via Direct Messages to their node or any other way we can find.
    • Nodes placed in any ROUTER mode need special consideration. Please visit our FAQ for more details.

  • Why move to ShortFast instead of creating another channel on LongFast?

    • We already have other channels on LongFast See here for a list. These channels still require everyone to be on the default frequency (slot) meaning that the traffic is all sharing the same nodes.
    • It is the same amount of work for users to move to a new slot but stay on LongFast as it is to move to ShortFast.
    • ShortFast comes with over 10x the bandwidth and we have found that our large mesh is reaching the limit of LongFast in some areas. Moving to ShortFast will allow our mesh to support more nodes and route more messages.

  • Can my node talk to LongFast and ShortFast at the same time over RF?

    • No. Each node can only talk to other nodes on the same frequency (slot) and same modem present (LONG_FAST vs SHORT_FAST).
    • This is why we are trying to communicate as broadly as we can, to get everyone over to ShortFast at the same time.

  • Will everyone go back to LongFast at the end of the experiment?

    • It depends on the outcome of the experiment, but tentatively YES, everyone is currently going to move back to LongFast at the end of the experiment.
    • If things go well, we will coordinate another move and details will be shared at that time. This allows for lessons learned from the experiment to be incorporated into the "official" recommendation to move all nodes to the new space.

How to Switch

The following methods can be used to join ShortFast. Just like joining LongFast for the first time, it is best to leave your node online overnight so it can see other nodes and join the mesh. Please share this information with others so we can have the best experience on ShortFast for this evaluation.

Manual

  1. Backup your current node configuration. This can be done via the mobile app or command line interface. Look for "Export configuration" and save it somewhere safe (it includes the node keys). This will make it easier to restore your node to the current configuration.

  2. Change the Modem Preset. Change it to "SHORT_FAST" and ensure the default frequency slot selection is "68". The frequency should be 918.875MHz. Everything else should be default. We do recommend selecting "OK to MQTT" but this is optional.

  3. Verify the Channel name changed. Most nodes will do this automatically but it is good to check that your default channel 0 is now called "ShortFast" (Case sensitive).

    • While you are here, verify that the channel "Downlink" is NOT enabled.

  4. Interval Frequency While it is not required. Please consider increasing your NodeInfo and Position Info to every 5hrs (18000s) or greater.

QR Code

Generally we recommend NOT using QR codes/links since they change settings on your node without informing you. Use QR codes from sources you trust, and verify your node settings after every use. Do NOT use this QR code with a station G2 or with any node that has an amplifier, since the tx power will be too high. It is still a good idea to create an export/backup of your config to make it easy to switch back. Using this QR code should configure your node to talk to others on ShortFast

May 2025 ShortFast QR

  • Primary Channel = ShortFast
  • Modem Preset = SHORT_FAST
  • Slot = 68 (918.875MHz)
  • Hops = 5
  • TX power = 30 dBm
  • OK to MQTT = True