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E22-400M30S (SX1268) - sensitivity of the receiver, AGC? #268

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opened 2026-10-05 05:55:53 +02:00 by adam · 8 comments
adam commented 2026-10-05 05:55:53 +02:00
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Hello!

I’ve been testing the E22-400M30S radio for a while now. I have a few of them, and I’ve noticed that sometimes it receives well, other times, it receives almost nothing (I can only receive one stronger station)
It seems to me that this might be related to the fact that sometimes strong interference appears on this frequency, which causes the noise floor to rise and the radio to freeze up?
I don’t know how to figure this out, but on LilyGo—which isn’t an SX126X—it works fine. I thought the SX1262 would receive better, and it does, but sometimes it freezes for a few minutes or even hours. I don’t know if this requires an AGC reset sometimes or if it’s related to something else.

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I don't know what the noise floor is like on this radio, but on the SDR it doesn't look too bad...

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I'm using the ESP32_DIY_1W_LoRa

Have any of you had any experience with this?

Hello! I’ve been testing the **E22-400M30S** radio for a while now. I have a few of them, and I’ve noticed that sometimes it receives well, other times, it receives almost nothing (I can only receive one stronger station) It seems to me that this might be related to the fact that sometimes strong interference appears on this frequency, which causes the noise floor to rise and the radio to freeze up? I don’t know how to figure this out, but on LilyGo—which isn’t an SX126X—it works fine. I thought the SX1262 would receive better, and it does, but sometimes it freezes for a few minutes or even hours. I don’t know if this requires an AGC reset sometimes or if it’s related to something else. <img width="1986" height="216" alt="Image" src="https://github.com/user-attachments/assets/30a0de58-08b7-4a14-a3e9-8ce158fed8ba" /> I don't know what the noise floor is like on this radio, but on the SDR it doesn't look too bad... <img width="1651" height="1198" alt="Image" src="https://github.com/user-attachments/assets/5ecf9e56-fe4c-4ae4-82d8-bdb6ea4b1054" /> I'm using the **ESP32_DIY_1W_LoRa** Have any of you had any experience with this? <!-- github-sync-id:4230693577 -->
adam commented 2026-10-05 05:55:54 +02:00
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I've seen that the sensitivity readings on SX1268 (400M30S) are not that accurate at all (RSSI and SNR values) so , without this happening, I see no explanation of the "blocking process" you experience.

Can you do more testing with two boards hearing the same packets? (not to compare RSSI / SNR , but to see it it listened them all ? (maybe using the free syslog ?)

I've seen that the sensitivity readings on SX1268 (400M30S) are not that accurate at all (RSSI and SNR values) so , without this happening, I see no explanation of the "blocking process" you experience. Can you do more testing with two boards hearing the same packets? (not to compare RSSI / SNR , but to see it it listened them all ? (maybe using the free syslog ?) <!-- github-comment-id:4214860869 -->
adam commented 2026-10-05 05:55:55 +02:00
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It’s not a problem that I have a lower SNR readings.
I just wanted to point out where the issue is. It’s just that this SX1268 radio stops receiving stations that are transmitting—I can see them on the SDR (connected to a different antenna). There are other digis in the area that transmit, for example, every 15 minutes.
So here’s what happens:
the SX1268 receives a lot of stations/frames in the area, and then it stops. I checked in the CPA software—the same thing happens, but there you can view the RSSI Noise Floor. Thanks to that, I know that when this happens, the Noise Floor locks at -74dBm (which is very high), whereas normally I have -103dBm. The radio can stay locked like this for a long time until the device is restarted but sometimes is unlocked without restart (no idea what happened).

So I tested Heltec Wireless Stick lite v3 (SX1262) and DIY E22-400M30S.
This happens less often on the Heltec than on the E22-400M30S. Maybe it’s because the E22 has an LNA?
I don’t have these issues with the SX1278 radio (Lilygo or DIY RA-02)

It’s not a problem that I have a lower SNR readings. I just wanted to point out where the issue is. It’s just that this SX1268 radio stops receiving stations that are transmitting—I can see them on the SDR (connected to a different antenna). There are other digis in the area that transmit, for example, every 15 minutes. So here’s what happens: the SX1268 receives a lot of stations/frames in the area, and then it stops. I checked in the CPA software—the same thing happens, but there you can view the RSSI Noise Floor. Thanks to that, I know that when this happens, the Noise Floor locks at -74dBm (which is very high), whereas normally I have -103dBm. The radio can stay locked like this for a long time until the device is restarted but sometimes is unlocked without restart (no idea what happened). So I tested Heltec Wireless Stick lite v3 (SX1262) and DIY E22-400M30S. This happens less often on the Heltec than on the E22-400M30S. Maybe it’s because the E22 has an LNA? I don’t have these issues with the SX1278 radio (Lilygo or DIY RA-02) <!-- github-comment-id:4215471318 -->
adam commented 2026-10-05 05:55:56 +02:00
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LNA is only enabled for TX and not over Rx.

maybe test a filter for the higher sensitivity of SX126X lora modules?

LNA is only enabled for TX and not over Rx. maybe test a filter for the higher sensitivity of SX126X lora modules? <!-- github-comment-id:4215514304 -->
adam commented 2026-10-05 05:55:56 +02:00
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I am testing now with 433 Band Pass filter but the issue is the same..
and LNA is on RX path. PA is on TX path.
I have confirmation that the same situation have my colleague (so different antenna and area :) )

I am testing now with 433 Band Pass filter but the issue is the same.. and LNA is on RX path. PA is on TX path. I have confirmation that the same situation have my colleague (so different antenna and area :) ) <!-- github-comment-id:4215684050 -->
adam commented 2026-10-05 05:55:57 +02:00
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I am testing now with 433 Band Pass filter but the issue is the same.. and LNA is on RX path. PA is on TX path. I have confirmation that the same situation have my colleague (so different antenna and area :) )

you see the same problem with SX1262 (Heltec V3) too ?

> I am testing now with 433 Band Pass filter but the issue is the same.. and LNA is on RX path. PA is on TX path. I have confirmation that the same situation have my colleague (so different antenna and area :) ) you see the same problem with SX1262 (Heltec V3) too ? <!-- github-comment-id:4215700140 -->
adam commented 2026-10-05 05:55:58 +02:00
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I am testing now with 433 Band Pass filter but the issue is the same.. and LNA is on RX path. PA is on TX path. I have confirmation that the same situation have my colleague (so different antenna and area :) )

you see the same problem with SX1262 (Heltec V3) too ?

Yes. And maybe it is related: https://github.com/meshcore-dev/MeshCore/blob/main/docs/faq.md#37-q-my-repeater-maybe-suffering-from-deafness-due-to-high-power-interference-near-my-meshs-frequency-it-is-not-hearing-other-in-range-meshcore-radios--what-can-i-do

Meshcore users had similar issue I think..

and maybe: https://github.com/jgromes/RadioLib/pull/1718

> > I am testing now with 433 Band Pass filter but the issue is the same.. and LNA is on RX path. PA is on TX path. I have confirmation that the same situation have my colleague (so different antenna and area :) ) > > you see the same problem with SX1262 (Heltec V3) too ? Yes. And maybe it is related: https://github.com/meshcore-dev/MeshCore/blob/main/docs/faq.md#37-q-my-repeater-maybe-suffering-from-deafness-due-to-high-power-interference-near-my-meshs-frequency-it-is-not-hearing-other-in-range-meshcore-radios--what-can-i-do Meshcore users had similar issue I think.. and maybe: https://github.com/jgromes/RadioLib/pull/1718 <!-- github-comment-id:4216109699 -->
adam commented 2026-10-05 05:55:58 +02:00
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Today I encountered this problem again with the Heltec Wireless Stick Live v3 (SX1262).
The tracker (SP6IZU-7) was driving near me and had a strong signal. After a few frames from that tracker, the radio went dead and stopped receiving. As you can see in the photo, it didn’t receive anything for over an hour; after that, I rebooted it and everything returned to normal.

Image
Today I encountered this problem again with the **Heltec Wireless Stick Live v3 (SX1262).** The tracker (SP6IZU-7) was driving near me and had a strong signal. After a few frames from that tracker, the radio went dead and stopped receiving. As you can see in the photo, it didn’t receive anything for over an hour; after that, I rebooted it and everything returned to normal. <img width="429" height="901" alt="Image" src="https://github.com/user-attachments/assets/7d89fcbc-096f-4da1-a1b3-cdcd5a195e1a" /> <!-- github-comment-id:4254458866 -->
adam commented 2026-10-05 05:55:59 +02:00
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can you re-test with latest firmware ?

can you re-test with latest firmware ? <!-- github-comment-id:5318387427 -->
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Reference: adam/LoRa_APRS_iGate#268