[LG01] Same packet, twice in application console

Hi everyone,

(sorry I can’t really categorized as I’m not sure where the problem come from…)

I having an issue with a packet send by my node to TTN. It appear twice into the application console:


the first duplication regroup every gateway that receive the message except one (mine, a LG01 for testing purpose only)


the second duplication is the message receive by the LG01.


As everything seam to be the same, I wonder how TTN differentiate one message to an other?
Did you already face this problem with any gateway, or with a LG01?



To help you understand what happen here, I can show you the data as seen in the gateway console:



@jota Did you notice that it says retry next the Frame Count and Port Number in your application console and that the Frame Counter value is the same?

The two attempts in your application console are separate attempts by your node to reach the gateway as you can tell by the RSSI values one is -48 and the other -114, not to mention the times are different. The gateway received the second attempt (the one with an RSSI value of -48).

Yes I notice that, and it’s not the problem…

The RSSI difference mean nothing, that’s two different gateway (look at the ID), one one my desk, one at several hundred meters of me, so that’s quite logical to have different RSSI…

The difference in time came from the same reason (in fact that’s how you locate a node with lora. )

Have a closer look to the screenshot, I can asure you it’s the same message.

EDIT: for me the problem came from the info about the frame: if you look closer, the LG01 have a frequency of 868100000 and the others 868,1… Two different way to right it, and I think TTN interpret that as two different frames.



You’ll have to excuse me, I didn’t understand what you wrote in your initial post as well as I thought.

I have never seen this issue with my LG01 even when I’ve tested it in close location to another gateway (a Laird Sentrius) that I also own, and I don’t think it has anything to do with the Dragino broadcasting it’s frequency in Hz instead of MHz. The only time that I’ve seen this is happen is when the node can’t connect to a gateway at first and then it manages to reach it on a secondary retry. Which is why I mentioned that in my first post when I hadn’t looked at the different gateway ID’s. Once again sorry for my apparent confusion.

No problem glbaum! I was not very explicit about the issue.

I fond this in the Learn section:

The current implementation of the backend locally de-duplicates uplink messages based on the md5 sum of the payload. The payload of the message will be the same for all duplicates, and the chance that during the de-duplication period (usually a couple of seconds) a different message with the same hash arrives, is extremely low.

Is this still like that in reality or the de-duplication of messages has changed?