Frequency Transformation to find transfer function

Discussion in 'Homework Help' started by naickej4, Aug 31, 2016.

  1. naickej4

    Thread Starter Member

    Jul 12, 2015
    182
    2
    Hello all,

    I am working through a past year exam with a provided memo from the lecturer (The Lecturer does not reply to his emails).

    I am trying to understand how the lecturer arrived at the final answer.
    Why did he introduce the LPF as 0.5?
    Is there a simple way to tackle this type of question?
    Is there information on this site that I can read that will help me further?

    The prescribed textbook that I am using is Digital signal processing: a practical approach / Emmanuel C. Ifeadhor, Barrie W. Jervis.

    thank you.

    upload_2016-8-31_14-14-43.png
    upload_2016-8-31_14-14-59.png
     
  2. DGElder

    Member

    Apr 3, 2016
    345
    85
    Perhaps from the equation for constructing a corresponding high pass filter from the low pass filter coefficients.

    where T is the period of the sampling frequency.

    flp = 1/(2T) - fhp

    And where the cuttoff frequency, f, is expressed as a fraction of the sampling frequency: T=1

    Flp = 1/2 - Fhp.

    ...must be in your book somewhere.
     
    Last edited: Aug 31, 2016
    naickej4 likes this.
  3. naickej4

    Thread Starter Member

    Jul 12, 2015
    182
    2
    Hi Sir,
    Thank you very much for your response. It makes a lot of sense on what you saying so that proves were the lecturer gets the 0.5 from but,
    what about the final answer, where does he get that from ?

    Below is the only information that I find in the text book on this type of question and there are no examples. (I took pics of the textbook)

    upload_2016-9-1_7-44-10.png

    upload_2016-9-1_7-44-32.png


    Thank you.
     
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