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...	...	@@ -909,5 +909,33 @@
909	909	(((
910	910	Under normal circumstances, users need to change the APPKEY to solve this problem.
911	911
912		-
	912	+
	913	+== 11.2  The node is very close to the gateway, but the signal is poor ==
	914	+
	915	+If you are using US915 or AU915, you found the frequency points of different subband ranges in your uplink
	916	+
	917	+Like that：Both 905.1Mhz and 902.3Mhz appear on uplink
	918	+ But they belong to Subband1 and Subband2 of US915 respectively
	919	+
	920	+Cause: The server and the gateway use different frequency bands (the server uses Subband1, and the gateway uses Subband2)
	921	+
	922	+ In server side, it shows the frequency is 905.1Mhz, which is sub-band2. But the RSSI is very low, Because this is not a signal in 905.1Mhz, it is on 902.3Mhz, the signal is too strong and appear a noise in 905.1Mhz.
	923	+
	924	+How to check the frequency band used by the server：
	925	+
	926	+You can view the information sent by the server: ch_mask in Unconfirmdedatadown
	927	+
	928	+[[image:https://qiye.aliyun.com/attachment/downloadex?ri=%2Falimail%2FinternalLinks%2FrefreshToken&o=1&et=normal&ext=png&e=jinggeng.bei%40dragino.cc&f=cd202b4b-8b20-46fe-8982-dbd243323d7a&m=1_0%3ADzzzzyP5He.%24---.ULjrwi40&n=temp4cj.png]][[image:https://qiye.aliyun.com/attachment/downloadex?ri=%2Falimail%2FinternalLinks%2FrefreshToken&o=1&et=normal&ext=png&e=jinggeng.bei%40dragino.cc&f=cd202b4b-8b20-46fe-8982-dbd243323d7a&m=1_0%3ADzzzzyP5He.%24---.ULjrwi40&n=temp4cj.png]]
	929	+
	930	+[[image:image-20230821113255-1.png]]
	931	+
	932	+According to lorawan's protocol, your first ch_mask is 7 for ChMaskCntl = 7 then 125 kHz channels are disabled. Simultaneously the channels 64 to 71 are set according to the ChMask bit mask.
	933	+
	934	+[[image:https://qiye.aliyun.com/attachment/downloadex?ri=%2Falimail%2FinternalLinks%2FrefreshToken&o=1&et=normal&ext=png&e=jinggeng.bei%40dragino.cc&f=f567abb7-c2b5-4d29-88ca-9c5885bd410b&m=1_0%3ADzzzzyP5He.%24---.ULjrwi40&n=temp4cj.png]][[image:image-20230821113539-2.png]]
	935	+
	936	+In the second message, the channel 0~~7 is true, which means that your server is using subband2.
	937	+
	938	+[[image:https://qiye.aliyun.com/attachment/downloadex?ri=%2Falimail%2FinternalLinks%2FrefreshToken&o=1&et=normal&ext=png&e=jinggeng.bei%40dragino.cc&f=9c126577-ab4f-4c55-be34-5f3410bccdcd&m=1_0%3ADzzzzyP5He.%24---.ULjrwi40&n=temp4cj.png]][[image:image-20230821113618-3.png]]
	939	+
	940	+Note:lorawan's protocol link——[[LoRaWAN® Regional Parameters v1.0.3revA (lora-alliance.org)>>url:https://resources.lora-alliance.org/document/lorawan-regional-parameters-v1-0-3reva]]
913	913	)))