pydsm.NTFdesign.psychoacoustic.dunn_optzeros

pydsm.NTFdesign.psychoacoustic.dunn_optzeros(n)

Helper function for synthesising psychoacoustically optimal modulators.

Returns the (normalized) zeros which minimize the in-band noise power of a delta-sigma modulator’s NTF after weighting by the F-weighting.

Parameters:

n : int

the number of optimized zeros to return

Returns:

zeros : ndarray of reals

the zeros for the modulator as normalized angular frequencies.

Notes

The zeros are always located on the complex unit circle. In other words, the zeros are returned as frequencies. For homogeneity with DELSIG’s ds_optzeros, the frequencies are normalized with respect to the signal bandwidth, that is fixed at 22.05 kHz.

This function is the equivalent of ds_optzeros in DELSIG. The tabled zeros delivered by this function are from [R2]. Note that this function does not return the values that are tabled in [R2], but scales them by the reference audio bandwidth used in [R2], namely 22.05 kHz.

[R2]	(1, 2, 3) Chris Dunn and Mark Sandler, “Psychoacoustically Optimal Sigma Delta Modulation,” J. Audio Eng. Soc., Vol. 45, No. 4, pp. 212 - 223 (1997 April)