Need Siganl to Nosie Ratio explained

I am researching and needing help with 430’s. Can someone explain what the signal to noise ratio is? or pass on a link to help. Not sure what the values mean. Thanks

simple it is the ratio of how loud the SM hears your signal compared to background noise.

lets say the ambient background noise is 80 db, and you hear your access point at 60db then your signal to noise ratio is 20 db.

it is -20db or it is 20db? I think it sould be (60-80)db = -20db

Receive Signal Level is measured in negative dBm.

So, technically, it's (-60) - (-80) = 20 dB of Signal-to-Noise.

The noise is -80 dBm and the Signal being received is -60 dBm, so in effect, the signal is 20 dB higher than the noise.

Does that make sense?  Is there a reason that this is important?