dB vs Dbm - signal strength

[Speedbird1]

Hi 

Just a curious one and trying to get my head around it 

The dashboard measures client signal strength with dB where a higher value is better i think 

But dbm a lower value is better 

My understanding is dbm  - Signal Strength and dB Signal to noise ratio (SNR) 

The dashboard displays signal strength but in dB

Is there any logic behind this as to why its not in dbm?

[ww]

Yes you should read it a snr

Its a better indication for the quality of the wireless connection

https://documentation.meraki.com/MR/WiFi_Basics_and_Best_Practices/Signal-to-Noise_Ratio_(SNR)_and_W...

https://www.watchguard.com/help/docs/help-center/en-US/Content/en-US/Fireware/wireless/ap_wireless_s...

[KarstenI]

You are right with your assumption that the value in dBm is the signal strength ans as @ww mentioned, the value in dB is SNR. But for both the higher numbers are better. Don't get confused by the dBm value which is normally negative.

[Speedbird1]

Thank you both for the info

[GIdenJoe]

To add to this information:
The dB value you see in dashboard is how much SNR the AP sees from the upstream signal coming from the client in question.

For a Wireless site survey 25 dBm is a good minimum SNR we use to design your network.  So if you see alot of clients in your network below that value you could have a coverage hole.

The charts on following link show what the minimum SNR is for each sent datarate.
https://wlanprofessionals.com/mcs-snr-rssi-chart/

[Speedbird1]

Thanks for that 

Most our clients range from 48-70db

Just a few mobiles around the 30db

No others below 30db