FFT Spectrum Analyzer
Freeware
fft analyzer
software free download
FFT Analyzer Freeware

Visual Analyser is a complete professional real time software, transform your PC in a full set of measurement instruments.
No new hardware necessary you can use the Sound Card of your PC, or you can use a specific external hardware for example Plug.n.DAQ Lite or RogaDAQ2.
VA is a real time program which simulates a set of electronic instruments, such as:
Oscilloscope (dual channel, xy, time division, trigger)
Spectrum Analyzer with amplitude and phase display (linear, log, lines, bar, octaves band analysis 1/3, 1/6, 1/9, 1/12, 1/24)
Wave-form generator with “custom functions”, triangular, square, sinusoidal (all with NO ALIASING and smooth transition), white / pink noise, pulse generation, DC generation [New!]
Frequency meter (in time and frequency domain) and counter; in time domain by means of a real time zero crossing algorithm
Volt meter with DC [New!], True RMS, peak to peak and mean display plus resolution calculation
Filtering (low pass, hi pass, band pass, band reject, notch, “diode”, DC removal)
Memo windows (data log) for analysis and storage of time series, spectrum and phase with “triggering” events; THD and Impedance data logging with spline interpolation; possibility to save the graphics in various format (.tee, .txt, .wmf)
Screenshot of Spectrum and Scope window
A TRUE software digital analog conversion (for complete signal reconstruction using Nyquist theorem)
Frequency compensation: possibility to create / edit a custom frequency response and add it to the spectrum analyzer computed spectrum; added standard weighting curves A, B, C [New!] in parallel with custom frequency response
Support for 8/16/24 bit soundcard by means of API calls
Internal 80 bit IEEE floating point variables for minimum rounding error
Cepstrum analysis , cross correlation
Extended THD measurements, with automatic sweep, compensation, data log
ZRLC meter with vector scope, automatic sweep in time and frequency for automatic measurement
Calibration mechanism (you can calibrate the VA scales directly in VOLT or dB or percent full scale)
Set of values computed in real time (peak to peak, peak, crest factor, form factor, true rms, mean, frequency with zero-crossing algorithm)
Wave file recording and playback
Custom FIR filters
Price: Freeware