Lora Node 151 - poor RSSI with Lorawan example code

#1

Hi everyone!

I am new to Lora and Lorawan, so still have a lot to learn, but I could not find a solution to a strange problem: If I download the basic hardware test code to two pieces of Heltec lora node 151 (one sender and one receiver/sender) they work well, they could communicate 700-800 meters away from each other (or maybe more, but this was my test distance).

But when I tested this node with TTN (dowloaded the lorawan example code and set everything for TTN as described) I could send data to the network (it appeared in TTN) but the RSSI is extremely poor, it was -110 when 5 meters away from the gateway (I tested it with other 151 node as well). The gateway is working well, so I guess it is a software issue. Or is it possible that the Lora Node 151 is simply not compatible with my gateway?

#2

Sorry, when we were designing the new version of Node151, we only exported PA_BOOST pin, but the output below 14dBm in the standard LoRaWAN protocol was not output through PA-BOOST. I think this is a design error of ours, and I would like to express it again apologize.
But you can still get around this problem with code. You need to modify the uint8_t SX1276GetPaSelect (uint32_t channel) function in line 153 of the sx1276-board.c file to change all outputs to the PA-BOOST pin.QQ%E6%88%AA%E5%9B%BE20200116110314

Thank you for your support of our products.

#3

Great! Thank you for your answer. I modified the code as you suggested and now it works well with good RSSI values.

#4

Hello,
I have a very similar issue with the Lora_Node_151_LoRaWAN_V1.2.raw example code. Hardware Version: 2.2.
Messages from node to a gateway in only 1 meter distance arrive only very sporadically. Maybe 1 out of 100 message arrives.
Joining to TTN thus takes many retries but works at some point. RSSI is very low ~-110 if a package arrives. I use a Dragino LIG 16 Gateway and it works flawless with other nodes.

I already checked the function SX1276GetPaSelect() but this already seems to be correct in the software version V1.2.

I tested this with two similar Lora 151 Nodes. Both behave very similar. I thus suspect a software configuration issue.

Does someone have any idea?

Thanks & Regards

#5

Is someone using the Lora Node 151 in combination with the LoraWAN example code V1.2 and got a normal RSSI value at the receiving side?
Are there any modifications necessary?