determinant of transfer function

Discussion in 'Homework Help' started by bhuvanesh, Jan 29, 2015.

  1. bhuvanesh

    Thread Starter Member

    Aug 10, 2013
    268
    2
    i am studying control system i crossed this transfer function

    H(jw)=(1-jw/1+jw)

    now taking determinant of this

    |H(jw)|=1

    My question in what way the determinant is usefull to learn about the systrem.Here the determinant of transfer function is 1,so the 1 saying anything about the system
     
  2. Veracohr

    Well-Known Member

    Jan 3, 2011
    551
    76
    It's saying the output amplitude is the same as the input amplitude. But that transfer function does do something useful...
     
  3. t_n_k

    AAC Fanatic!

    Mar 6, 2009
    5,448
    782
    Google "non-minimum phase systems".
     
  4. MrAl

    Well-Known Member

    Jun 17, 2014
    2,433
    490
    Hi,

    Are you sure it was 1-jw/1+jw ?
    I ask because that jw/1 looks suspicious. It is unusual to show a '1' in the denominator because that just means it simplifies into just the numerator.
    This leads me to believe it could have been instead:
    1-jw/(1+jw)

    I am not saying that this is definite, just that it could have been read wrong or even printed wrong on the source page.
    No problems if it was correct all along.

    Of course it could also have been:
    (1-jw)/(1+jw)

    which would also make more sense, but it's a good idea to show all the parens when writing these mathematical expressions out.
     
  5. Veracohr

    Well-Known Member

    Jan 3, 2011
    551
    76
    That's what I assumed.
     
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