Improve Heltec v4 RX reception with undocumented register patch

[Socalix]

Following several rounds of testing Heltec v4 RX reception as part of PR #1249 I found out that the best solution was using the original v1.11.0 code, with undocumented register 0x8B5 patch (setting LSB=1) as desribed by @Quency-D (Heltec engineer) here:
#1249 (comment) and without the RX Boosted Gain feature.

This PR is doing just that: turning on the 0x8B5 LSB and turning off RX Boosted Gain flag.

=== Additional Details ===

Test Process:
I put RAK4631 and Heltec v4, both with Alfa 915 antenna and repeater v1.11.0 firmware in the same location (attic, about 7 inches apart). I then took Heltec T114 with companion v1.11.0 about 1.25km (0.75mile) away and did ping every 3 seconds to the same repeater about 20-30 times. I then flashed the v4 with different firmwares and pinged again.

Test Sample:

RAK4631 v1.11.0	Heltec v4 PR1249 w/o RegPatch	Heltec v4 PR1249 w/RegPatch	Heltec v4 PR1398 w/RegPatch and no Boosted Gain
-4.25	err	4.75	5.5
err	err	err	6.25
-2.75	err	2.75	err
3.75	3.5	err	4.25
1.75	5.5	2.0	5.5
3.0	err	6.0	4.75
err	err	err	1.25
1.75	4.75	err	7.75
4.0	3.25	-0.25	err
4.75	3.0	1.75	2.5
-7.5	4.25	5.0	2.0
6.75	4.25	2.25	err
err	err	err	5.5
6.25	err	4.0	0.25
3.75	err	-0.75	err
20% err	55% err	33% err	25% err

[Socalix]

Repeater builds for testing:
heltec_v4_repeater-1.11.0-pr1398-builds.zip

pr1398 - Standard build - without any extra flags
pr1398-debug - Debug build - with USB_MODE, USB_CDC, MESH_DEBUG, MESH_PACKET_LOGGING flags
pr1398-packetlog - Standard build with MESH_PACKET_LOGGING flag only
pr1398-boost-packetlog - Standard build with RX_BOOSTED_GAIN and MESH_PACKET_LOGGING flags

[spiralshapeturtle]

@Socalix thanks for this spinoff. It would get more traction if you embed the table from your last post in the other PR with the results.

Would you do me a favor for the letsmesh MQTT output the debugging should be off to keep my RS232 stable.

Could you build a set with this flag only?

I love to test the files.

Build firmware with the -D MESH_PACKET_LOGGING=1 flag enabled using PLATFORMIO_BUILD_FLAGS.

PS: I have a cavity I could test with the RX boosted gain also. But not want to mesh up your PR. Let me know.

[olanwe]

I guess that this patch can also be applied to the Heltec Tracker v2.

[weebl2000]

I guess that this patch can also be applied to the Heltec Tracker v2.

See also this branch: https://github.com/weebl2000/MeshCore/tree/semtech_patch - I've added it for Heltec Tracker v2 there.

I'm not sure about the boosted gain=0. For me it seems boosted gain still improves reception.

[Socalix]

@Socalix thanks for this spinoff. It would get more traction if you embed the table from your last post in the other PR with the results.

Good idea. PR summary updated with testing information.

Would you do me a favor for the letsmesh MQTT output the debugging should be off to keep my RS232 stable.
Build firmware with the -D MESH_PACKET_LOGGING=1 flag enabled using PLATFORMIO_BUILD_FLAGS.
PS: I have a cavity I could test with the RX boosted gain also. But not want to mesh up your PR. Let me know.

Updated the zip file above with a new "pr1398-packetlog" and "pr1398-boost-packetlog" builds.

[Socalix]

I guess that this patch can also be applied to the Heltec Tracker v2.

Yes, you can simply add -D SX126X_REGISTER_PATCH=1 flag and comment out SX126X_RX_BOOSTED_GAIN in the heltec_tracket_v2/platformio.ini file to turn it on.
I don't have Tracker v2, so I cannot test it myself.

[spiralshapeturtle]

@Socalix thanks for this spinoff. It would get more traction if you embed the table from your last post in the other PR with the results.

Good idea. PR summary updated with testing information.

Would you do me a favor for the letsmesh MQTT output the debugging should be off to keep my RS232 stable.
Build firmware with the -D MESH_PACKET_LOGGING=1 flag enabled using PLATFORMIO_BUILD_FLAGS.
PS: I have a cavity I could test with the RX boosted gain also. But not want to mesh up your PR. Let me know.

Updated the zip file above with a new "pr1398-packetlog" and "pr1398-boost-packetlog" builds.

Thanks my second V4 arrived today going to test on the similar antennas.

[excalq]

Thanks for this fix! I've been tying to get my v4 node connected to the area mesh, and though I could TX fine (packets seen on analyze.letsmesh.net), I rarely was getting responses. Tried 5 different antennas. This branches firmware seemed to have solved all the issues for me.

[spiralshapeturtle]

@Socalix

It's quite difficult to test here because the mesh network is so busy that the ping test you performed isn't possible at my location. There are too many transmissions which could interfere with pings from other locations. Both units are running quite stable, though one of them has a 2% higher RX (receive) level. I'll swap the antennas tonight (by changing the pigtail cables) to see if the 2% increase is related to the unit itself or the antenna.

Any other tips for testing are welcome.
1.11.0-pr1398-boost-packetlog-4575800 (Build: 15-Jan-2026)

1.11.0-pr1398-packetlog-4575800 (Build: 15-Jan-2026)