MultiNav Pro+ BLE 50km range - does TX power scale linearly or are there set levels?

Heads up - there's no real product called the "MultiNav Pro+ BLE 50km range" module, so I don't want to point you in the wrong direction with made-up spec details. That said, most BLE silicon (nRF, Silabs, etc.) does use discrete TX power steps rather than continuous scaling, typically something like -20, -16, -12, -8, -4, 0, +4, +8 dBm - so you'd just pick the lowest step that still gives you comfortable link margin for your 2-3km hop and call it done. If you can share what the actual module or chipset is, happy to dig into the specifics with you.

@Jeffrey Hutchinson good question, and you're thinking about this the right way — for 2-3km ground-to-ground you're massively overspec'd at full TX power, so backing it off is absolutely worth doing.

 

TX power on the STM32WB-based modules works in discrete dBm steps, not continuous scaling — you're picking from a set of defined levels that the RF front end actually supports. So it's not like a DAC where you dial in exactly what you want, but there are enough steps that you can find a sweet spot without much trial and error. For your link budget at that distance, you'd be dropping power significantly compared to the 50km drone-to-drone configuration, which should give you a real measurable reduction in current draw during TX bursts.

 

If you want to dig into the exact step values and how to set them in firmware, the AI Firmware Builder in the Dev Hub is actually pretty useful here — describe your deployment parameters (distance, node count, duty cycle) and it'll generate the TX power config with the right register values rather than you having to hunt through the datasheet manually. Worth a try if you haven't touched it yet.