Testing Questionnaires

System Message: ERROR (

Unknown directive type "questionnaire"

.. questionnaire:: Test Questionnaire
  :timelimit: 600
  :deadline-date: 2006-11-29 23:59

  This is a test of the questionnaire handling.

  With some questions:

  .. multiple-answer:: compand

    :question: Which of the following statements about companding are true
    :choices:
      :1: Companding is a bit reduction technique
      :2: Companding increases the quantisation SNR for weak signals
      :3: Companding degrades the analogue signal
      :4: The companding characteristic has a linear and a logarithmic
          proportion
      :5: Companding is often implemented using a segmented linear
          quantisation characteristic.
    :answer: '(list 1 2 4 5)
    :feedback: 
      Companding does not degrade the analogue signal. Its
      purpose is to improve the signal to noise ratio, and while the signal
      to noise ratio for large signals is increased overall the SNR is much
      improved with companding.

  .. multiple-choice:: dpcm
     
    :question: In differential pulse code modulation (DPCM) do we
    :choices: 
       :1: Transmit the integral of the signal
       :2: Transmit differences between actual sampled
           amplitudes and predicted amplitudes
       :3: Adapt the quantisation characteristic as the average
           signal amplitude varies
       :4: Have a quantisation characteristic which has small
           steps for small amplitudes and large steps for
           larger amplitudes
       :5: Transmit an estimate of the signal
    :answer: 2
    :feedback: 
       In DPCM we use transmit differences between actual sampled
       amplitudes and amplitudes predicted using a linear combination of
       previous samples. This difference will be much smaller than the
       signal amplitude and so will require less bits to represent it.

  .. numeric:: Nyquist
     :params: (omega (+ 50 (random 500)))
              (a (+ 1 (random 25)))
              (n  (/ omega pi))

     :question: A waveform, `a`:eval: + `a`:eval: sin(`omega`:eval:
                t+0.7) is to be sampled periodically and reproduced from these
                sample values. How many sample values must be stored
                to reproduce 1 sec of this waveform.
     :weighting: 0.5
     :format: "~,2f"
     :answer: n
     :tol: (/ 1.1 n)
     :feedback: The frequency of this waveform is `omega`:eval: /2
                `\pi`:math: = `"~,2f" (* 2 n)`:eval: Hz .
                We require (from Nyquist sampling 
                theorem) at least 2 samples per period, so the sample
                frequency must be `"~,3f" n`:eval: Hz.


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