sos2tf() - Signal Processing

sos2tf converts a second-order section representation
of a given digital filter to an equivalent transfer function representation.[b,a] = sos2tf(sos) returns
the numerator coefficients b and denominator coefficients a of
the transfer function that describes a discrete-time system given
by sos in second-order section form. The second-order
section format of H(z) is given
byH(z)=∏k=1LHk(z)=∏k=1Lb0k+b1kz−1+b2kz−21+a1kz−1+a2kz−2.sos is an L-by-6 matrix
that contains the coefficients of each second-order section stored
in its rows.sos=[b01b11b211a11a21b02b12b221a12a22⋮⋮⋮⋮⋮⋮b0Lb1Lb2L1a1La2L].Row vectors b and a contain
the numerator and denominator coefficients of H(z)
stored in descending powers of z.H(z)=B(z)A(z)=b1+b2z−1+⋯+bn+1z−na1+a2z−1+⋯+am+1z−m[b,a] = sos2tf(sos,g) returns the transfer
function that describes a discrete-time system given by sos in
second-order section form with gain g.H(z)=g∏k=1LHk(z).

Syntax

[b,a] = sos2tf(sos)[b,a] = sos2tf(sos,g)

Example

Transfer Function Representation of a Second-Order Section SystemOpen This Example
Compute the transfer function representation of a simple second-order section system.
sos = [1  1  1  1  0 -1; -2  3  1  1 10  1];
[b,a] = sos2tf(sos)

b =

    -2     1     2     4     1


a =

     1    10     0   -10    -1

Output / Return Value

Limitations

Alternatives / See Also

Reference