Missing transmissions

What reasons would explain the missing transmissions?

The Elsys device transmits every 5 minutes but the data at TTN clearly shows not all transmissions are received.


The node could be on the limits of range for instance.

You could describe your setup; what for instance is the ‘Elsys device’, where is it, how far away is the gateway etc.

  • SF, RSSI and SNR of the received packets;

This is not a reliable transport; it’s a shared band, and all sorts of things can happen.

That said, you should examine the downlink at 18:42:41 and interpret the various MAC commands it may contain, they could include things like commanding less than optimal configuration of the node

It is well within range. Maybe the problem it is too close? The Elsys node is 3 mtrs from the internal Multitech AP gateway.


I would never have guessed that was your situation.

Why do you say “this is not a reliable transmit” ? What do you specifically mean by this?

It is a quality LoRa device node (Elsys) and so too is the Multitech gateway. Both quality devices. Do you think it is a setting?

That might actually be your problem.

A node very close to gateway might jam the gateway.
I did some testing some time ago using a RPi / RAK831, and a node within a couple of meters resulted in strange data from the gateway.

  • sometimes data appeard on the wrong channel
  • sometimes data was dropped by TTN-network
  • sometimes data was dropped by the gateway (no data sent)

When I moved the node longer away (4-5 meter) from the gateway all packets showed in the console.


Thanks Henning
I will move it further away and test

LoRa is not a reliable transport in that it the data does not always get through. Anything on a radio is subject to interference, and in digital schemes that usually means trying again.

LoRaWAN has a very weak mechanisms for doing retries, but it’s not really a viable scheme (as it fails to account for the nearly equal possibility that it is the ack which was missed).

Generally it’s better to simply send new data than to try to re-send increasingly stale data; and usage guidelines for TTN mean you generally can’t use confirmed mode to begin with. So realistically what you do is send measurements at a reasonable rate and hope enough of them get through to fit your needs.

The more LoRaWAN usage there is in a given location, the lower the chances that any particular transmission will get through.

Yay, there is cheerie news for the future of LoRaWAN!

To be honest I have very many sensors across several gateways and do not experience many issues. It was just this one and I think the answer was it was simply too close to the gateway.

I have moved it further away and all seems good

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I have seen this myself when we were new to the hardware. You will see some strange behaviour with a node too close to the Gateway! Data being received on multiple channels was one. All I can think is the node is too ‘loud’ for the gateway in close proximity.

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Since moving the node to over 4 mtrs away the transmissions have been flawless for over 48 hrs. All is good

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typical for me too. If you have to learn, you put everything on the bench, and… soon you have something to debug and understand.