SNR / PER in nRF Conect SDK

[hiteshk014]

Hi,

We're using nRF Connect SDK 1.9.1, we have a requirement of getting SNR / PER values in nRF connect SDK.

do we have any provision to get these values from physical layer if possible ?

Thank you,

Regards,

Hitesh

[haakonsh]

Hi Hitesh, 

Torbjørn is not available at the moment and I will handle your case instead. 

hiteshk014 said:

Any Ideas how do we get the signal strength of noise floor in the area?

I'll start by defining what exactly RSSI is a measure of because it is vital in order to understand how it relates to SNR and noise floor. The Received Signal Strength Indicator is a measure of the received RF signal in a given channel at the point of sampling. In essence it's an ADC sample of the voltage present in the receiver's analog front-end. The vital piece of infromation here is that any RF signal present in the given or adjacent channels will increase the value of the measured RSSI. RSSI does not directly measure the signal strength of any particular signal, but the sum strength of all of signals present. 

Usually RSSI is sampled automatically when receiving a packet in order to estimate its signal strength, but you can also sample RSSI manually when you are not receiving a packet. If you sample each channel while your wanted signal is not present you can estimate the noise floor based on the RSSI samples. 

I'm not quite sure what problem you are trying to solve by estimating the current SNR for a particular radio link, but if it is to improve Packet Error Rate for BLE links then I suggest you study the Bluetooth LE Quality of Service module for nRF Desktop, as it solves that exact problem. It increases PER by identifying noisy channels and updating the BLE connection's Channel Map where the noisy channels are removed. 

hiteshk014 said:

According to Nordic inputs : SNR is as follows:

Since RSSI is only an indication of RSS, you can only find an indication of SNR. 

hiteshk014 said:

Please share some way to get PER value as well from nRF Connect SDK. 

I don't fully understand what you are asking for.
Why do you need to know the PER value? What problem are you trying to solve, and why do you think that a PER value is needed to solve it?

BR,
Håkon Holdhus.