No change in spreading factor even in long distances


  • I have used two different antennas on the same end node device and tested them both in same conditions.
  • I have enabled Adaptive Data Rate (ADR) for both tests but have got no change on one and proper change on the another.
  • I have shared the spreading factors and SNRs of both tests below.
Range (m) 20 40 60 80 100 120 140 160 180 200 210 230 260 280
Antenna 1 SF7 SF7 SF7 SF7 SF7 SF7 SF7 SF7 SF7 SF7 SF7 SF7 SF7 SF7
4 2.2 0.5 0.5 -1.5 -1 -7 -5 -2.8 -2.2 -6.8 -8.8 -7.5 -6.8
Antenna 2 SF7 SF8 SF8 SF9 SF9 SF9 SF10 SF10 SF10 SF11 SF12 SF12 SF12 SF12
10.2 8.7 8.1 6.3 5.8 2.5 1.8 1.3 0.9 -1.7 -3.1 -8.9 -11.8 -16.2
  • At longer distances the SNR of the Antenna 1 didn’t drop much but the packet losses was very high, due to which only 1 out of 10 data packets would reach the LNS.
  • The Antenna 2 device worked correctly.

What could be the issue?

what antennas are the two?

high gain antennas become more directional and have null zones so antenna orientation to the node can have a influence

look at the radiation patterns of each antenna

are you sure you have the correct sma connectors?

do you have clear line of sight?

no obstructions?

if so i would not expect a sf12 at such short distances

Guesswork at the moment.

Although you might know the environment, you did not describe it, so we cannot know what the 280m involves, clear open air line of sight, dense wet forest, many outside buildings, inside a building with metal walls ?

And if you have a differance in antenna ‘performance’ then provide details of the antennas.

And I would concur with @Piet_Pillay, SF12 at such short distances is not normal, but that of course depends on the ‘environment’.

A lack of an extra 0 on the range? 280m is hardly a stretch.

We’d need all the details above.

And exactly what device & firmware it is running.

And is the SNR what the device hears or what the gateway hears (basis of calculation).

And how many uplinks, ADR doesn’t kick in immediately except on a join that is really obviously OTT.

Looks to me:

Antenna 1 - lost uplinks - no ADR backoff as downlinks are rxd 1/10
Antenna 2 - lost downlinks - ADR backoff due to no downlink rxd