SNR (Signal to Noise ratio) :
- As SNR = Signal Strength (dBm)/ Noise Floor(dBm)
- Noise floor is the measure of the signal created from the sum of all the noise sources and unwanted signals
- Since dBm is in logarithmic scale, SNR is obtained by subtracting the noise from the signal strength i.e (SNR = Signal Strength – Noise Floor)
- The minimum required SNR for a receiver varies depending on the bit rate or modulation.
- A positive SNR is required (i.e., signal strength should be a higher than the noise)
- E.g if a radio (client device) receives a signal of -75 dBm and the noise floor is measured at -90 dBm, the SNR is 15 dB [ -75 – (- 90) = 15 ]
- SNR value decreases if the length between receiver and Sender increases. Because of Loss / Attenuation .
- An increase in RF interference from microwave ovens and cordless phones, which increases the noise level, also decreases SNR.
- A higher SNR value means that the signal strength is stronger in relation to the noise levels, which allows higher data rates.
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