Duty Cycle Budget: count airtime, and make traffic wait #32

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2026-10-05T20:07:19Z

twisla commented

2026-10-05 20:07:19 +00:00

What

The share of airtime the Region allows (CONTEXT.md: Duty Cycle Budget): compute each packet's time on air, keep the total over the last hour, and hold outgoing traffic when the budget is used up.

What's known

EU868's 869.4 to 869.65 MHz sub-band allows 10 %: 360 s of transmission in any hour. Meshtastic's region table says the same.
A LoRa packet's time on air follows from its length, spreading factor, bandwidth, coding rate and preamble: a formula from Semtech's datasheet, pure maths, host-testable against published calculators. On LongFast a short text message takes several hundred milliseconds.
Relaying spends the same budget as our own messages: a busy mesh can use it up for us.
The budget survives a restart only if it's stored; forgetting it on reboot would let a crash loop exceed it.

Questions

A sliding hour, or fixed windows?
What waits and what's dropped when the budget runs out: our own messages first, relayed ones dropped?
Where it shows: the Status Bar, the Messenger, lora status.
Is the budget kept across restarts (NVS), and how often is it written?

## What The share of airtime the Region allows (CONTEXT.md: Duty Cycle Budget): compute each packet's time on air, keep the total over the last hour, and hold outgoing traffic when the budget is used up. ## What's known - EU868's 869.4 to 869.65 MHz sub-band allows 10 %: 360 s of transmission in any hour. Meshtastic's region table says the same. - A LoRa packet's time on air follows from its length, spreading factor, bandwidth, coding rate and preamble: a formula from Semtech's datasheet, pure maths, host-testable against published calculators. On LongFast a short text message takes several hundred milliseconds. - Relaying spends the same budget as our own messages: a busy mesh can use it up for us. - The budget survives a restart only if it's stored; forgetting it on reboot would let a crash loop exceed it. ## Questions 1. A sliding hour, or fixed windows? 2. What waits and what's dropped when the budget runs out: our own messages first, relayed ones dropped? 3. Where it shows: the Status Bar, the Messenger, `lora status`. 4. Is the budget kept across restarts (NVS), and how often is it written? ## Related CONTEXT.md (Region, Duty Cycle Budget), `lib/meshtastic/src/meshtastic_presets.h`, #31, #30.

twisla added this to the M5 Mesh transmit milestone 2026-10-05 20:07:19 +00:00

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twisla added a new dependency 2026-10-05 20:07:19 +00:00

#31 Radio Service: a transmit path, behind the Region