Units RSSI and SNR


#1

What are the units used for the RSSI and SNR of a mote and what are good and bad values for these factors? I seem to get no change in SNR, while I do get change in RSSI when moving around. The SNR stays around +9, is this good or bad?


#2

RSSI stands for Received Signal Strength Indicator. The minimal value of RSSI depends on your gateway. Normally it is around -120dBm. SNR stands for Signal-to-noise ratio. The minimal value of SNR is about -20dB. Which means +9dB is a quite good signal. :grinning:


#3

Thanks for the reply. What would be a realistic maximum value for the SNR?


#4

Around 10 dB is a realistic maximum. If you're close to the receiver. :slight_smile:


(Jasp215) #6

RSSI is always a negative number and units is dBm. From my testing of my outdoor gateway my nodes range from -80dBm to -125dBm and are able to send signals to the gateway.

For SNR there is little information online about it, it may be SNR or SNR margin that you are seeing. For the SNR I been getting values from +6dB to -10dB. The negative values mean that the device can receive signal below the noise floor and the higher the absolute value, the less noise you have.