thinQmaster Virtual testing partner Adaptive practice exams that find your weak spots and drill them. Every answer explained. From $69
Enroll

thinQmaster

Find your exam

Five questions free, before you decide.

Step 1 · choose a vendor

In one of our camps? Your practice exams come with the tuition — they are on your study page already.

Commonly confused · Wireless & Mobility

RSSI vs SNR: What's the Difference?

RSSI measures how strong a received signal is, usually expressed in dBm. SNR measures how much stronger the signal is than the background noise floor, expressed in dB. A strong signal can still perform poorly if noise is also high, so SNR is the better quality indicator.

vs

Signal-to-Noise Ratio (SNR)

Full definition
RSSISignal-to-Noise Ratio
MeasuresReceived signal strengthSignal strength relative to noise
UnitsdBm (or a vendor-specific index)dB
How obtainedMeasured directly by the radioSignal (dBm) minus noise floor (dBm)
Good values-67 dBm or stronger for voice/video25 dB or higher for voice/video
Better numberCloser to 0 (e.g. -55 beats -75)Larger (e.g. 30 dB beats 15 dB)
Tells youCoverageLink quality and achievable data rate
Remember it

RSSI is how loud the speaker is; SNR is how loud compared to the room.

Exam tip

Expect a calculation: signal -65 dBm with noise floor -92 dBm gives an SNR of 27 dB. Remember dBm values are negative and closer to zero is stronger.

Tested on

More Wireless & Mobility look-alikes