The present code is a Matlab function that provides:
1) Plotting of:
- the signal in the time domain;
- the amplitude spectrum of the signal;
- the power spectrum of the signal;
- the power spectral density of the signal.
2) Displaying of:
- the average Amplitude Spectral Density before A-weighting;
- the average Power Spectral Density before A-weighting;
- the average Amplitude Spectral Density after A-weighting;
- the average Power Spectral Density after A-weighting;
- the output noise (by Oscilloscope) before A-weighting;
- the output noise (by TrueRMS Voltmeter) before A-weighting;
- the output noise (by Oscilloscope) after A-weighting;
- the output noise (by TrueRMS Voltmeter) after A-weighting.
Two examples are given in order to clarify the usage of the function. The input arguments are given in the beginning of the code.
The code is based on the theory described in:
 A. Kay. Operational Amplifier Noise: Techniques and Tips for Analyzing and Reducing Noise (Chapter 5). Oxford, Newnes, 2012.
 B. Cordell. Designing Audio Power Amplifiers. New York, McGraw-Hill, 2011.
 Design Response of Weighting Networks for Acoustical Measurements ANSI S1.42-2001. Washington, American National Standards Institute, 2001.
 Electroacoustics Sound Level Meters Part 1: Specifications IEC 61672-1:2002. Geneva, International Electrotechnical Commission, 2002.
 D. Manolakis, V. Ingle. Applied Digital Signal Processing (Chapter 14). Cambridge, Cambridge University Press, 2011.
 G. Heinzel, A. Rudiger, R. Schilling. Spectrum and spectral density estimation by the Discrete Fourier transform (DFT), including a comprehensive list of window functions and some new flat-top windows. Hannover, Max-Planck-Institut für Gravitationsphysik, 2002.
 Хр. Живомиров. Измерване на някои шумови параметри на усилвателите с приложение на Matlab. Трети международен научен конгрес „50 год. Технически университет – Варна”, 4 – 6 Октомври 2012, Варна. Third International Scientific Congress Proceedings, ISBN 978-954-20-0551-3, Vol. 2, pp. 32-37, 2012.
A new version of the code has been uploaded.
Typos correction has been made.
A new version of A-weighting filter has been added.