Poor RSSI at close range

End Devices (Nodes)
1

Hello everyone,
I am fairly new to using LORAWAN and I have been getting poor results while using various bits of hardware. While using the Dragino Lora Shield, InAir9B and RFM95W in separate tests I cannot get a range past 100m LOS and my RSSI values are no better than -90dBm at a range of 3m. I’m using the RAK2758 gateway. I tested performance between two lora nodes and got good results however I cannot translate this to lorawan.
I don’t believe my hardware is wired wrong since the Dragino Shield works poorly out of the box. Could the problem be the code? I am using the standard “hello world” OTAA example from the LMIC libraries on 915mhz (all hardware is for 915mhz)
If there is any information you may need to help fix this problem please ask.
I appreciate any support you can add.

Regards,
Angus.

2

Comparisions at very short distances are often not very informative, unless you have a node that you know works well at long distance, then you can use that as a comparision.

3

Thanks for the reply,
None of the nodes I tested could reach a range past 100m. At 30m they showed rssi values around -110. Unfortunately I don’t have a node that works at longer ranges to use as a comparison.

4

The SNR figure is far more useful for telling you how close to failure the reception is.

-7.5db SNR for SF7 as I recall.

5

At a distance of 30m the signal returned -10.8db SNR for SF12 (rssi: -116dbm) and -11.8 db SNR for SF7 (rssi: -116dbm).
I hope this helps.

6

Those are very weak signals, although -11.8dB SNR for SF7 ought not to be possible, the failure level is -7.5dB SNR.

Looks like something is operating without an antenna connected.

7

I think you’re right. I’m thinking it must be the gateway since a test between lora nodes worked well with a range of a few hundred metres.
To test the gateway I connected one antenna and tested max range (25m) then a different antenna and then no antenna (I know its a bad idea) and all tests yielded the same result…
I’ll be contacting RAK since the gateway may be faulty.
Thanks for your help!

8

Instead of using one ant then none try swapping to a different ant and make sure connection tight (small spanner) vs finger tight…and dumb question but you have check ant conn type on GW’s & nodes right. ?(Sma m vs f vs rp-m vs rp-f etc.) as not unknown for use of no centre mating pin the ant only capacitively coupled giving weak signal. Also if GW’s operated without ant RAK would be well within rights to tell you get lost wrt replacement :wink: as is v. Bad idea! Though experience shows they are very good wrt service and response in such cases so you may be lucky… :slight_smile:

9

Good thinking I’ll try a different antenna and see the results.
The sma connectors are all the right ones and done up tight
Thanks for the advice!