Do you mean the 1/24 Octave resolution (for Level 4)? If so what is/do you regarded as a suitable resolution (for audio work)?
I have been running TrueRTA, for a few years. I use it specifically for sound reinforcement spectrum analysis and find that it is suitable as an RTA, function generator, pink and/or white noise generator and handles fast sweeps respectively.
Just stumbled over this thread... I'd like to add MATAA to the list of (free) audio analyzer software. It's different from other software, because it's basically an extension package for Matlab or GNU Octave (powerful number crunching software packages). The learning curve may be a bit steep for Matlab / Octave newbies, so it's not for everyone. But the data processing possibilities of MATAA are almost unlimited. And it works on Mac OS X, Linux, and Windows.
The resolution of a FFT or ability to accurately portray small signals mixed with noise, is primarily set by the number of data points it can analyze.
What constitutes adequate resolution depends on what you are doing. Its all about the right tool for the job!
People who test loudspeakers and acoustics generally can get by with small (e.g. 4096 point) FFTs.
People who test DACs and amplifiers are generally looking for 65k point FFTs, more or less.
Commercial and freeware FFT programs supporting up to 2 million or more points can be found and sometimes used advantageously.
Google "FFT resolution" for lots of tech articles and tutorials. Examples:
https://www.onosokki.co.jp/English/hp_e/c_support/faq/fft_common/fft_general_4.htm
FFT Fundamentals (Sound and Vibration Measurement Suite) - Sound and Vibration Measurement Suite 6.0 Help
http://www.analog.com/media/en/training-seminars/design-handbooks/MixedSignal_Sect5.pdf
IME, just about any of them.
One popular package I don't see mentioned is the Audio Rightmark program (freeware), which includes a FFT analysis module but is far more comprehensive - it automatically runs a fairly complete suite of tests:
Download. Audio Rightmark
Another program is ARTA - the no-pay demo version can be pretty useful.
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Thanks for the link. I will run it on my Windows Matlab machine and give it a run-through.
Large FFTs are commonly used to resolve signals at frequencies that are close to other signals. For example, if you want to see the funny things that happen when you digitize a signal that is very close to the Nyquist frequency.
Another example is excavating signals that are well below the noise floor.
Examples please of "Commercial and freeware FFT programs supporting up to 2 million or more points ....."
Dan.
Freeware/shareware: Rightmark audio Analyzer:
Latest News. Audio Rightmark
"new FFT Size options: 2, 4, 8 millions for analysis of any WAV files (the most right button in RMAA main window);"
Let me know how it does. I am pretty sure I should (and could) improve the manual describing the installation procedure, so plaese ask and comment if something does not work out of the box (via PN or email address in the MATAA manual).
MATAA
GNU Octave (free) or Matlab (totally not free), via import of audio data file
Audacity
But why would you want to analyse such a long signal?
I wish to measure/analyse system and device AF and VLF/ULF noise.
I figure on multiple/different signal types, but one would be pink noise sourced from a CDP, soundcard or other player.
I envisage recording system output or bridge amplifier output during excitation with 60 min+ recordings and then analysing the recordings.
I am open to suggestions on how to analyse....ie FFT or DFT and window etc settings.
Dan.
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