Dictionary:Phase characteristics (multichannel)
A multichannel filter can be expressed as a matrix. It is minimum phase if its determinant (which can also be expressed as the product of doublets) is minimum phase. For example, a multichannel response produced by impulsive inputs might be:
|input channel 1||input channel 2|
|output channel 1||(2+z)||(z)|
|output channel 2||(1)||(6+z),|
with the determinant 12+7z+z2=(3+z)(4+z), which is minimum phase; hence the multichannel response is minimum phase. Statements similar to those for single-channel phase characteristics can be made for maximum phase, linear phase, or zero phase. See also Sheriff and Geldart (1995: 290-1, 550-2).