1. FIR filters are always stable non-recursive
free of phase distortion all of the above
2. A 9-term moving average filter has an approximate -3 dB frequency of
?/9 radians 2?/9 radians ?/3 radians 2?/3 radians
3. Phase distortion means that
the phase response of the filter is linear
some frequencies take longer than others to move through a filter the phase delay is constant for all frequencies all of the above
4. The filter whose impulse response is h[n] = h[2]?[n] + h[1]?[n-1] + h[0]?[n-2] +
h[1]?[n-3] + h[2]?[n-4]
is recursive is unstable
does not display phase distortion is a moving average filter
5. A shift of an impulse response in the time domain affects
neither the magnitude nor the phase response of the filter the magnitude but not the phase response of the filter
the phase but not the magnitude response of the filter both the magnitude and phase responses of the filter
6. The impulse response for an ideal low pass filter cannot be used in practice because it is
infinite and non-causal infinite and causal finite and non-causal finite and causal
7. Truncation of the impulse response for an ideal low pass filter causes
the filter to become high pass
the impulse response to become infinite ringing to be eradicated
filter shape to degrade from the ideal 8. Transition width is
the distance in Hz between pass band edges for a band stop filter the distance in Hz between pass band edges for a band pass filter the distance in Hz between pass and stop band edges for any filter the phase delay of a filter 9. Pass band ripple is
20log(1-?p) ?s
the maximum gain in the pass band ?p
10. Stop band ripple is
?p
the maximum gain in the stop band 20log?p
none of the above
11. Ordering the windows from most to least according to the stop band attenuation they produce gives:
Hamming, Kaiser, Hanning Blackman, Hamming, rectangular Hanning, Hamming, rectangular rectangular, Blackman, Kaiser 12. Ringing is
equal to -21 dB produced by side lobes
caused by sharp signal transitions the result of echoes in the time domain
13. The purpose of the window in windowed FIR filters is
to make the number of terms in the impulse response finite to obtain an ideal filter response to produce a sinc variation to ensure the filter is stable
14. The larger the number of low pass FIR coefficients
the lower the pass band edge frequency the smaller the transition width the slower the roll-off
the greater the stop band attenuation
15. A low pass FIR filter with a stop band attenuation of 44 dB and a transition
width of 2.5 kHz for a sampling frequency of 8 kHz requires a
Hanning window with 5 terms Hanning window with 11 terms rectangular window with 21 terms Kaiser window with 5 terms
16. A low pass FIR filter with a pass band edge frequency of 3 kHz, a stop band edge frequency of 3. 5 kHz, and a stop band gain of 0.00178 must be designed. If the sampling frequency is 12 kHz, the design requires a
Hanning window with 95 terms Hanning window with 74 terms Hamming window with 83 terms Hamming window with 143 terms
17. Convolving a two-sided spectrum with a single spike in the frequency domain
samples the spectrum
shifts the spectrum to the location of the spike makes the spectrum causal makes the spectrum finite
18. A band pass FIR filter has the centre frequency 2 kHz and passband
edges at 1.75 kHz and 2.25 kHz. The low pass filter with the same shape has
its pass band edge at 2 kHz and a 250 Hz transition width its pass band edge at 250 Hz and its stop band edge at 750 Hz its pass band edge at 1.75 kHz and its stop band edge at 2.25 kHz its pass band edge at 250 Hz and an unknown transition width 19. A band stop FIR filter can be obtained by
windowing a low pass FIR filter