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Sal@mander.xyz

what kind of speed can LoRa really do? (lemmy.zip)

submitted 3 days ago by shortwavesurfer@lemmy.zip to c/meshtastic@mander.xyz

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scenario: In the future, it is possible to update your node on your 200-foot tower by simply sending the firmware file directly to the node with a zero hop direct connection

I know short fast can get about 10kbps (1KB/s) across the link, but thats just too slow to send a 1.5MB firmware update. I know that short turbo is illegal in some places, and I believe it's because it's using a bandwidth of 500KHz instead of the 250KHz of short fast.

So if you turn the error correction way down to almost off what is about the maximum bandwidth you could hope to possibly get out of the LoRa connection at 250KHz?

Even if you could pull off 125kbps (12.5KB/s) that would only require two minutes to send the firmware file from your node to the receiving node up on the tower.

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[–] corsicanguppy@lemmy.ca 4 points 3 days ago* (last edited 1 day ago) (1 children)

the maximum RAW bit rate of this LoRa chip is 62.5 kb/

Sooo, 1998 "USR X2" dial-up speeds.

1.5mb is okay. 32mb we used 'at' to schedule (just so we'd get the mail when it was done) and go to lunch.

Keep in mind, when USENet was in full swing, we had entire institutions daisy-chained off a single 56k incoming line like a trunk line, from America to Vancouver through Edmonton and then Calgary. The best and brightest surfed binaries and alts like mad off that single chain.

It's really usable if we tune our workflow.

[–] Sal@mander.xyz 3 points 3 days ago

I agree. I think that a firmware update taking several minutes to complete would be alright. If loss of service is a concern, they can keep more than one device at the tower and one acts as a backup while the other updates.

One problem is that the data rate I quoted is the maximum capacity for a continuous stream. In practice, that is often illegal due to duty cycle rules. So, you might get 40 kbps while transmitting, but local laws may let you transmit only 1% of the time. If you choose to be obedient it will take a lot longer to get the firmware across.

Even then, let's say it takes a few hours to get the full firmware, I think this can be alright for sporadic firmware updates.