Estimate Noise Floor Of Spectrum

The noise figure denoted nf sa and the thermal noise energy.

Estimate noise floor of spectrum.

Noise estimate by tracking the noise only regions of the noisy speech spectrum. Johnson nyquist noise thermal noise johnson noise or nyquist noise is the electronic noise generated by the thermal agitation of the charge carriers usually the electrons inside an electrical conductor at equilibrium which happens regardless of any applied voltage thermal noise is present in all electrical circuits and in sensitive electronic equipment such as radio receivers can. More instructional engineering videos can be found at http www enginee. Similarly a noise like signal will appear 3 db above the noise floor.

The spectral estimate corresponding to the rectangular window has the expected noise floor but the spectral estimate using the hann window has a noise floor that is about 2 dbm higher than expected. In radio communication and electronics this may include thermal noise black body cosmic noise as well as atmospheric noise from distant thunderstorms and. In the improved mcra approach cohen 2003. Characterization of the frequency content of noise using the power spectral density.

If for example we wanted to determine the noise floor from 0 to 1 ghz would it be best to run a sweep using a full 1 ghz span or would it be better to pick various frequency ranges with smaller spans. The reason for this is that the spectral estimate is compute at 512 frequency points but the power spectrum is integrated over the rbw of the. The total power in the resolution bandwidth at each frequency point. Ignoring noise and channel effects each frequency is either at maximum or at the noise floor.

If the noise floor is changing as you change bandwidths it implies that one is measuring power spectrum i e. With a spectrum analyzer what is a good method for determining the local noise floor in the lab area around the spectrum analyzer. Consequently the apparent noise level will change with rbw whether one is measuring the noise of a device under test or the instrument. The trick to noise spectrum analysis is that many sample power spectra squared magnitude ffts must be averaged to obtain a stable statistical estimate of the noise spectral envelope.

The amplitude of the thermal noise energy is given by the product of three parameters ktb where. In signal theory the noise floor is the measure of the signal created from the sum of all the noise sources and unwanted signals within a measurement system where noise is defined as any signal other than the one being monitored. This is the essence of welch s method for spectrum analysis of stochastic processes as elaborated in 6 12 below. These regions are found by comparing the ratio of the noisy speech to the local minimum against a threshold.