How to calculate noise floor

1. How is noise floor measured?
2. How do you calculate noise floor in FFT?
3. What is the noise floor in dB?

How is noise floor measured?

Scales used to measure it

The dBFS scale is usually used for input or output signals, to measure at the (digital audio) converter stage, in your soundcard. Another method of measuring noise floor is using a sound pressure level (SPL) meter.

How do you calculate noise floor in FFT?

Average FFT Noise Floor (dB) = 6.02n + 1.76dB + 10 log(3*M / (pi * ENBW)), where M is the number of data points in the FFT. A reasonable number of samples for the FFT of a 12-bit converter is 4096.

What is the noise floor in dB?

Noise floor is an important parameter in spectrum analyzers and vector network analyzers. It determines the lowest possible signal level that these systems can measure. For example, to measure a signal that is -140 dBm, the system must have a noise floor of less than -140 dBm.