MultiNav Pro+ BLE - does output power scale down automatically at short range?

The MultiNav Pro+ doesn't do automatic TX power scaling based on proximity out of the box - it'll just sit at whatever power level you've configured (or max by default). You'll want to manually dial down the TX power in your firmware config if your nodes are staying that close; at 50-200m you can probably drop it significantly and free up some power budget too. Worth checking the RSSI values you're already getting and working backwards from there to find a comfortable floor.

@Susan Martinez yeah, that's correct — no automatic TX power scaling out of the box, it'll hold whatever you set it to (max by default). At 50-200m you genuinely have a ton of headroom to work with, so pulling that power down in firmware is absolutely the right move.

 

The RSSI-based approach you mentioned is the practical way to do it — log your RSSI at your typical operating distances first, then dial back TX power until you're sitting comfortably above your sensitivity floor with some margin for environmental variation (buildings, rain, whatever your field conditions throw at it). You don't need to be aggressive about it either; even a moderate reduction makes a real difference in current draw, which adds up fast if your nodes are battery-powered or running off the supercap kit.

 

If you want to get fancier you could implement a simple closed-loop RSSI feedback in your firmware to adjust TX power dynamically as nodes move around, but honestly for fixed or slow-moving field nodes at that range, a static lower power setting is probably all you need.

Yeah Jessica is right, and honestly the power savings can be pretty noticeable once you tune it down - I was running a similar setup and knocked the TX power way back for short-range nodes, made a real difference on battery life. If you're already logging RSSI, just watch the floor over a few days across different conditions and give yourself maybe 10-15dB of headroom above your worst case before you lock in a setting.

If you want to get a bit fancier than a static config, you could implement a simple closed-loop adjustment in firmware - poll RSSI periodically and step the TX power up or down to hold a target link margin, basically rolling your own basic power control. Not always worth the complexity but if your nodes are mobile and the range varies a lot it might be cleaner than guessing at a fixed floor.

Charles's approach is solid if your nodes are moving around a lot, but if they're mostly static or predictably routed I'd honestly just go with a fixed conservative power level and call it done - less moving parts to debug later. I did something similar on a project last year, settled on a power setting that gave me ~15dB margin at my worst-case node and never had to touch it again.

Seconding the static fixed power approach if your nodes aren't moving much - way less headache than rolling your own power control loop. One thing worth doing though is testing your RSSI across a few different real-world conditions before you lock in your floor, I got burned once assuming line-of-sight numbers would hold up once some foliage and equipment got in the way.

To answer your original question - no, the MultiNav Pro+ BLE doesn't do any automatic TX power scaling based on range, it'll just run at whatever you configure and hold it there. So yeah, you're probably blasting at max right now. Given your nodes are mostly static in that 50-200m window, I'd just log RSSI for a few days like Thomas said, find your worst-case floor, and dial in a fixed power level with some headroom - way easier than it sounds and you'll likely be surprised how much you can back it off.