Guide to the Packet Forwarder

I need to edit the sub-bands that I use in the US915 band. Is there a comprehensive guide to how the packet forwarder configuration file works?

Hello @Keith
Packet forwarder configuration file for US band can be found here
For more information on Semtech Packet forwarder you can see here
You can find the global_config.json file in /opt/ttn-gateway/packet_forwarder/lora_pkt_fwd/ on your Gateway.
Please do not forget to stop/start or restart the packet forwarder after the changes are made.


Thank you for this response. I have seen all of these resources and I know how to edit the global_config.json file. The problem I am having is that all of the US915 examples use sub-band 2. There is no example of any other sub-band being used, and there is no guide to the use of the global_config.json file.

So, back to my original question - is there a comprehensive guide to how the packet forwarder configuration file works?

Hei @Keith,

Perhaps I can try to help. True there is no guide at least to my knowledge, perhaps it is good to make one.
Starting with which of the 64 channels you want to use exactly?
In short it is like this, generally you have 8 channels, which are multi-SF, meaning that you are limited to these 8 anyways so you simply need to pick 8 and edit the configuration file, this being said a general rules is that the two SX12xx that each take care of 4 channels respectively can not handle too large a separation so you need to group the close together in the worst case 2 groups of 4 or better yet one block of 8, these however can be any of the 64 (well technically not any, but I hope you get my point).
Perhaps you can point out the 8 you want to use and I will see if I can make it work for that specific set and also try to provide instructions on what is done , why and how, etc.
Hopefully this will be the start of something resembling a guide.
I hope this helps.

What do I set the freq to for US915 sub band 0 or sub band 1 respectively?


I think Sub-Band 2 is most common, but really it depends on what your node is using in the end I suppose.


Simplest approach would be to take the configuration for one sub-band and add/subtract 1.6 MHz a number of times to get another, so that the sub-IFs are being moved as a group relative to the two radio IFs.