PHASELOCK Phaselock Gabor coefficients
Usage: c=phaselock(c,a);
PHASELOCK(c,a) phaselocks the Gabor coefficients c. The coefficients
must have been obtained from a DGT with parameter a.
Phaselocking the coefficients modifies them so as if they were obtained
from a time-invariant Gabor system. A filter bank produces phase locked
coefficients.
Phaselocking of Gabor coefficients correspond to the following transform:
Consider a signal f of length L and define N=L/a.
The output from c=PHASELOCK(dgt(f,g,a,M),a) is given by
L-1
c(m+1,n+1) = sum f(l+1)*exp(-2*pi*i*m*(l-n*a)/M)*conj(g(l-a*n+1)),
l=0
where m=0,...,M-1 and n=0,...,N-1 and l-an is computed modulo L.
PHASELOCK(c,a,'lt',lt) does the same for a non-separable lattice
specified by lt. Please see the help of MATRIX2LATTICETYPE for a
precise description of the parameter lt.
References:
M. Puckette. Phase-locked vocoder. Applications of Signal Processing to
Audio and Acoustics, 1995., IEEE ASSP Workshop on, pages 222 --225,
1995.
Url: http://ltfat.github.io/doc/gabor/phaselock.html
See also: dgt, phaseunlock, symphase.
Package: ltfat