Interpreting RSSI & SNR

[Lawrence Griffiths]

Are there in guides/help on Interpreting RSSI & SNR from a Ping.
Surveying a site I was Getting RSSI -113db & SNR of -5dbm on SF9.

I was able to send 1 in 3 times.
So with an RSSI range -140dB and SNR -20dbm
It looks on paper I’ve got some head room before I fall off the cliff.
But on-site experience feels like I’m on the edge of the cliff, so to speak and should try SF11/12 etc.

Any help welcome

Lawrence

[Jason Reiss]

Using the Link Check will give the demodulation margin above the SNR floor for the packet spreading factor.

For BW125 the lora demod SNR floors in dBm are
SF7 => -7.5
SF8 => -10.0
SF9 => -12.5
SF10 => -15.0
SF11 => -17.5
SF12 => -20.0

For BW250 add 3.0, BW500 add 6.0

[Lawrence Griffiths]

Jason, thanks as non RF type apologies for dumb questions but pondering how I use this data.

So for example on BW125 from your post
1. I’m seeing approx -12.0dBm on SF9 I should consider using SF10?
2. I’m seeing approx -9.0dBm on SF9 I could consider using SF8?

I do hope someone is working on the “How to Commission a LoRaWAN” book

[Lawrence Griffiths]

Ok can the AT cmd guide be updated please to include the meaning of the Link Check result.

// From LoRaWAN spec!
A value of 0 means that the frame was received at the demodulation floor (0 dB or no margin) while a value of 20 for example, means that the frame reached the gateway 20 dB above the demodulation floor.

Thanks

• This reply was modified 7 years, 5 months ago by Lawrence Griffiths.

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