Filter Design Toolbox

islinphase

Test quantized filters to see whether they are linear phase

Syntax

• flag = islinphase(hq)
  flag = islinphase(hq,k)
  

Description

flag = islinphase(hq) determines if the quantized filter hq is linear phase, and returns 1 if true and 0 if false.

flag = islinphase(hq,k) determines if the kth-section of the filter hq is a linear phase section and returns 1 if true and 0 if false.

The determination is based on the reference coefficients. A filter has linear phase if it is FIR and its transfer function coefficients are are symmetric or antisymmetric. If it is IIR and it has poles on or outside the unit circle and both numerator and denominator are symmetric or antisymmetric, it is linear phase also.

Examples

This IIR filter has linear phase.

• num=[1 0 0 0 0 -1];
  den=[1 -1];
  hq = qfilt('df2t',{num,den});
  islinphase(hq)
  ans =
  
       1
  

See Also
isallpass, isfir, ismaxphase, isminphase, isreal, issos, isstable

isnone

ismaxphase