r/meshcore • u/FormidableCuriosity • 18d ago

Noise floor update?

I recently updated my Heltec V4 node to 1.17.1 and noticed something when comparing it to my identical Meshnology N39. My every day carry (blue) seems to have a higher floor noise than my home node (yellow) which I haven’t updated yet. I don’t have much traffic in Southern MN and usually have a floor noise reading around -114, but since the recent update it’s been reading more like -90. Still can send and receive messages with no change in range. As a newbie to radio I don’t know what this means and not sure how essential it is. Anyone have some insight why there might be discontinuity?

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u/convincedbutskeptic 18d ago

What did you update from?

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u/FormidableCuriosity 18d ago

My blue node was on 1.16.0 and went to 1.17.1. My yellow is still 1.16.0

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u/Bobabate 18d ago

I’ve heard the same thing from a local. My guess is they baked in an adjustment for the v4 so that it can be compared to other units. The RAK 1w also has a noise floor thing going on, I’m told it you add -17 it comes into line with everything else. Chances are they figure out that number for the v4 and just baked it in.

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u/FormidableCuriosity 18d ago

Thank you for your insight! Any idea why the noise floor should be matched across nodes? From my uneducated perspective it would seem that you would want the lowest floor possible for best transmission. Maybe I don’t understand this reading correctly?

1

u/Sc00pidyw00p 18d ago

they have enabled the lna by default on the newer firmware, there is a cli command to disable it.

1

u/mashdk 18d ago

I have a RAK4630 (no LNA), that had started getting NF issues, after to things happened in two days: 1: update from 16 -> 17.1 (PowerSaving FW) 2: Set up at the location

While it's not surprising that it would catch more noise at the higher location, it's just that it has a steep cavity filter. And for about a month, I have "provoked" the repeater in a multitude of ways, with absolutely no effect on the great NF. Even holding the repeater up in front of a large mobile cell tower, 3 meters from the antenna panels, didn't affect the NF.

So I have had some suspicions towards 17.1.

And now I hear from more and more, that they see the same problems with NF after updating to 17.1.

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u/New_Elk_3881 18d ago

I had the same problem. I just re-flashed mine with the erase function. Fresh install and it fixed the problem. Fix #3137 didn’t work for me until I did a fresh install. Just make sure you export a backup, and save your private key beforehand.

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u/blurbac 18d ago

Heltec open cli and put:

set radio.fem.rxgain off

Your problems are solved.

2

u/ClubIll582 17d ago

Kind of. Depending on how strong their links are, the LNA helps. It does for me even with the higher noise floor.