dB vs Dbm - signal strength

Speedbird1
Getting noticed

dB vs Dbm - signal strength

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

 

Speedbird1_0-1660833665326.png

 

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

 

 

 

5 Replies 5
ww
Kind of a big deal
Kind of a big deal
KarstenI
Kind of a big deal
Kind of a big deal

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
Getting noticed

Thank you both for the info

GIdenJoe
Kind of a big deal
Kind of a big deal

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
Getting noticed

Thanks for that 

 

Most our clients range from 48-70db

Just a few mobiles around the 30db

No others below 30db

 

 

Get notified when there are additional replies to this discussion.
Welcome to the Meraki Community!
To start contributing, simply sign in with your Cisco account. If you don't yet have a Cisco account, you can sign up.
Labels