Noise floor significantly increased on Heltec V4.3 with v1.17.0

[drewsed]

Description

Since upgrading to MeshCore v1.17.0, the noise floor on my Heltec V4.3 repeater has become significantly worse.

Before the upgrade, the noise floor was around -115 dBm. With v1.17.0, it is now around -80 dBm under the same conditions.

This is a significant degradation of approximately 30 dB and affects the receiver's ability to detect weak LoRa signals.

Expected behavior

The noise floor should remain close to the level seen with the previous firmware, around -115 dBm.

Actual behavior
Hardware: Heltec V4.3
Firmware: MeshCore v1.17.0
Previous noise floor: ~ -115 dBm
v1.17.0 noise floor: ~ -85 dBm
Difference: ~30 dB

The antenna, location and hardware setup have not been changed.

[Magalex2x14]

FEM LNA was turned off in 1.16
In 1.17 it is turned on by default and you can control it from the console - try set radio.fem.rxgain off

[ErikBrown2]

There is still an issue. The 'set radio.fem.rxgain off' setting is not persisted. After a reboot the rxgain is back to on. This should be persisted.

[drewsed]

thank you both. I also think this setting schould be persisted

[cwichura]

#3137 contains a fix for this.