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Improve Heltec v4 RX reception with undocumented register patch #1398
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Repeater builds for testing: pr1398 - Standard build - without any extra flags |
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@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. |
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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. |
Good idea. PR summary updated with testing information.
Updated the zip file above with a new "pr1398-packetlog" and "pr1398-boost-packetlog" builds. |
Yes, you can simply add |
Thanks my second V4 arrived today going to test on the similar antennas. |
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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 Thank you for testing! Yep, I'm "lucky" to be the only one running Meshcore around me.. :)
Looks like the one without the RX Boosted Gain has around 3db lower noise floor, which could translate to 2% more lower-signal packets getting picked up. Of course can also be antenna and location related, so switching things around will be interesting. Since you have 6% TX, I wonder if having both repeaters running next to each other at the same time means that we're seeing them helping each other get more packets? i.e. only one repeater hears the original packet and the other repeater hears the packet from the first one repeating it, so the RX % will be similar. |
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@Socalix test without TX mode. Firmware: 1.11.0-pr1398-boost-packetlog-4575800 (Build: 15-Jan-2026) Well I have run them without TX for a while and I put the SNR/RSSI values into claude.ai. Below the summary which I can reuse upcoming week after swapping the pigtails today. Im only swapping the IPX connector on the boards and keep everything the same. As stated earlier I have to different antennas so that could still be a factor to mitigate by swapping the connectors. WARNING below is an AI generated summary. |
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Here is a big question and I'm hoping someone can help. How can we use this running Powersaving10 firmware so that we can turn off the LNA pre-amp at noisy tower sites. This would be a game changer. But we cant use the standard 1.11 firm as it draws to much power. suggestions ? 1/19/2026 update - its there already...... "powersaving on" and your set |
These tests are great! The difference of 20% RX with Boosted Gain and 25% without boost I believe confirms that TX enabled in the prior test let the repeaters "help" each other hear packets, so definitely TX disabled is the right way to test. Also 5% difference by itself may not sound much, but it's 25% better RX over the one with boosted gain. I also agree with the AI summary as it matches my previous tests - boosted gain is reducing the node's ability to hear some packets and causes the SNR overall to be lower. After you complete the test with flipped antennas, it would be great if you don't mind running one more test - pr1398-packetlog vs standard v1.11.0 so that we can see the RX difference there. |
This PR fix includes 2 things:
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I have the test equipment to test this but my knowledge on how to modify the code is where Iack. Is this a command line entry? what do i download and how how do I bring it up and I'll find the rest. So I have the powersaving10 file and what to do from there? |
I don't know how it works with the file and coding, but I can tell you that on my V4 I can use the "powersaving on|off" command. So it might come with the nightly builds where the power saving is already included for the v1.12.0 release. Just type "powersaving on" For the record my tests are done without powersaving enabled. |
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Hello guys, I was doing some tests on #1249 and while i was on it I also tried this PR. Here is a crosspost from the findings Hello guys Stock firmware: Reference: 296 messages, V4 received: 284, loss: 4 % |
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@Socalix I only swapped the antenna IPX connector and now 24 hours later the result is as follow. AI summarized the data.
Firmware: 1.11.0-pr1398-boost-packetlog-4575800 (Build: 15-Jan-2026)
Firmware: 1.11.0-pr1398-packetlog-4575800 (Build: 15-Jan-2026)
PA5B Houten repeater is quite far away from me and that seems to be the differentiator, more on that at the bottom. I asked AI again about the far away repeater, arround 2 PM I changed the antenna cable where you can see the load rising and lowering, so the antenna with the tape label is better. Yesterday the (better) antenna with the tape label was on this node: This 24hours I swaped the (better) tape labeled antenna to this node
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@spiralshapeturtle Can you also clarify which changes the boost-packetlog and packetlog firmwares contain? boost-packetlog -> is this boosted_gain=0 and the register fix? |
#1398 (comment) i just copied this, the only thing I know. |
packetlog = this PR which means register patch and NO boosted gain flag turned on. |
Thanks for testing! This is an interesting test and results. What antennas are you using on these nodes? |
I think the AI summary is a bit confusing today, but if I understand the letsmesh graphs correctly - what we see today is that antenna choice has a bigger impact on RX % than boosted gain flag. We still see the same 20% RX vs 25% RX on the same antennas regardless of the boosted gain. Correct? |
Antenna is: https://www.laskakit.cz/nicerf-sw868-zd210-antena-3dbi-21cm-868mhz/ ( on both nodes ) Also for the additional tests: |
Correct! The packet increase is related to the better antenna. But the interesting part is this see the distance table. Edit: can copy it on mobile will do tonight. Antenna Swap Test Results - Yesterday vs TodayTest Configuration
Better antenna = Original antenna without tape Complete Node Detection & Performance ComparisonUtrecht Node (~13.6 km)
Key Finding: Both firmwares show significant performance degradation with standard antenna Radome West Node (~4.0 km)
Key Finding: Anomaly - boost-packetlog improved with standard antenna (likely temporal variation) PA5B Houten Repeater (7.25 km)
Key Finding: Only packetlog firmware detects this repeater, regardless of antenna Zeist Slot (0.91 km) - Local Node
Key Finding: Only boost-packetlog detects this local node loramesh.nl (8.02 km)
Key Finding: Only boost-packetlog detects this node Zeist Sanatoriumbos (2.66 km) - Problem Node
Key Finding: Node has become unreachable for both setups today Summary StatisticsNode Reach Comparison
Performance Changes After Antenna SwapV4_2 (boost-packetlog): Better → Standard Antenna
Net Result: +2 nodes, -1 node, mixed performance V4 (packetlog): Standard → Better Antenna
Net Result: No new nodes, significant score decreases Critical Observations1. Antenna Performance is ComplexThe "better antenna" shows:
2. Firmware Dominates Results
3. Temporal Variations Matter
V4 (packetlog) with Better antenna achieved the highest single score (902) and best SNR (6dB), making it the optimal choice for long-range mesh networking. boost-packetlog excels at discovering local nodes but benefits less from the better antenna, suggesting its signal processing is optimized differently. |
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@Socalix which one should I flash with the regular firmware? |
Yes did that! So packetlog v.s. standard is running now, where standard is on the better antenna and should get the same percentage RX. |
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Just tested both the PR1398 packetlog and the PR1398 Boost Packetlog and both support Powersaving! This is amazing - I did not see this mentioned! it works! To confirm, the PR1398-packetlog has the LNA (17db pre amp) DISABLED. Is this correct? |
Awesome. We're just trying to figure out what is the optimal configuration - with or without Boosted Gain, so having 2 nodes next to each other and comparing RX like you did sounds great. |
I just checked on it. It seems that the Powersaving PR was merged to the dev branch a month ago, so it was not in the v1.11.0 firmware, but it's included here because PRs are branched from dev.
Both build have the register patch. The "PR1398-packetlog" also has the "RX_BOOSTED_GAIN" flag turned off. I am not sure if/how this is changing the LNA. My understanding is that it's SX1262 flag only. This is from Semtech documentation: |








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: