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Xinyuan-LilyGO / LilyGo-LoRa-Series

LILYGO LoRa Series examples
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Regarding the LoRa Chirp Issue of T3-S3 SX1280 2.4G With PA. #193

Open Wanghaoyu920 opened 1 month ago

Wanghaoyu920 commented 1 month ago

Hi everyone,

I am currently using the T3-S3 SX1280 (with PA) development board with the following parameter configuration: BW=406.25, SyncWord=0x12, SF=12, CR=8. I modified the RadioLibExamples/Transmit_Interrupt(https://github.com/Xinyuan-LilyGO/LilyGo-LoRa-Series/tree/master/examples/RadioLibExamples/Transmit_Interrupt) program according to the above configuration and successfully flashed it onto the development board.

Next, using a USRP B210 in GNU Radio, I captured the packets and performed a spectrum analysis, and I obtained the following spectrum. 微信截图_20240806172548

At this point, the preamble symbols have become DownChirp instead of the usual UpChirp. What could be the issue here? Is there a corresponding option in the program to configure UpChirp/DownChirp? I hope someone can help me resolve my doubts. Thank you.

Wanghaoyu920 commented 1 month ago

I seem to have found the problem. In SX1280Dataset (https://semtech.my.salesforce.com/sfc/p/#E0000000JelG/a/3n000000l9OZ/Kw7ZeYZuAZW3Q4A3R_IUjhYCQEJxkuLrUgl_GNNhuUo), page 132 mentions packetParam5 = InvertIQ/chirp invert, which allows the chirp to be flipped. But during the initialization of the program, this parameter is set to 0x00 by default, for example https://github.com/Xinyuan-LilyGO/LilyGo-LoRa-Series/blob/b7b4d0e944206dbcf05a86d6faf1a03dc96c4b54/lib/RadioLib/src/modules/SX128x/SX128x.cpp#L501.

github-actions[bot] commented 1 week ago

This issue is stale because it has been open for 30 days with no activity.