Plotting the spectrum on the first 12 seconds of this file starting at 2048 points.
https://www.dropbox.com/scl/fi/9u77ljnt39jjrbgf7w3q1/500Hz_BPSK31_Idle_-_Letters_-1_original_FLdigi_TX_Generate-_.FLAC?rlkey=4mzrgtgy8pe6ouujtssssxnrs&dl=1
As the # of points increases the peak value increases above -12dB but the plot line disappears eventually. Is there some way to increase the maximum scale to 0dB?
Voxengo SPAN is a free plugin that works in Audacity …
That appears to be for real-time. I’m reporting a bug in the standard Spectrum analysis.