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Questions for Todd Krieger

Posted by real_jj on June 17, 2006 at 11:29:33

1) In what way does oversampling improve baseband SNR? (it does, your job is to explain how)
2) In what way does noise-shaping improve baseband SNR?
3) Why is dithering not the same as noise shaping?
4) Why is dithering not the same as oversampling?
5) How does one do 4:1 interpolation in sampling rate?
6) How does one do 4:1 decimation in sampling rate?
7) Why is TPD understood by the vast majority of people to be the right kind of dither?
8) Why is looking at the output of a DAC without any interpolation filter a meaningless behavior?
9) When is dither added, before or after anti-alias filtering?
10) Why does dither work in the sampled (digital) domain, without any D to A conversion ever being necessary?
11) What is the phase shift of the slowest possible highpass filter?
12) What does it mean to have a "resonance" in a highpass filter?
13) What kind of highpass filter arrangement models the behavior of the organ of corti well?
14) When in audio signal processing does one use the convolution theorem in the form wherein spectra are convolved?
15) How did Shannon prove Nyquist's sampling conjecture?
16) Where does the convoluation of the impulses represented in the digital domain with the rectangular function in a baseband DAC happen?
17) Why must any DAC use anti-image filtering?
18) What kind of errors will will high-frequency images introduce in poorly designed electronics?
19) What is the difference between a step in the time domain, and a step in the frequency domain?
20) How do delta-sigma convertors use oversampling, and to what end?
21) How do delta-sigma convertors use noise shaping, and to what end?
22) What is the primary reason for the massive (say 128x) oversampling in a delta-sigma convertor?
23) Is it necessary to dither a delta-sigma convertor?
24) If so, how?
25) What would the ideal (i.e. theoretical) SNR of a 65536 oversampled delta-sigma convertor with 7th order integration be in the baseband?
26) Why does a delta-sigma convertor use an out-of-baseband lowpass filter?
27) What pushes the noise in a delta-sigma converter up out of the baseband, well above the baseband Nyquist frequency?
28) What kind of model can one use to represent the unfiltered output of a delta-sigma DAC?
29) What is the basic transform duality?
30) What does the duality theorem apply to?
31) How does one capture and reproduce (accurately) a signal at 3/4 of the sampling frequency?
32) How does one capture and reproduce (accurately) a signal at 117/4 of the sampling frequency?
33) What is wrong with the statement "you can never reproduce any signal larger than half the sampling frequency".
34) What is integer band sampling?
35) What is quadrature sampling?
36) What is SSB?
37) What is DSB?
39) What is AM/SC?
40) How does a Quadrature Mirror Filter work?
41) How is a wavelet like a Quadrature Mirror Filter?
42) How is an MDCT like a Haar wavelet?
43) What IS a Haar Wavelet, anyhow?
44) What's the difference between a Haar Wavelet, a Dabauchies Wavelet, and a Bi-orthogonal frequency-optimized wavelet?
45) How is an MDCT like a transform?
46) What makes an MDCT not a transform?
47) What is Parsival's Theorem?
48) What does A A' = I mean?
49) When is A A' undefined?
50) When is A^(-1) = A'

You will be graded. None of the questions are trick questions, and all have well-known answers.

This post is made possible by the generous support of people like you and our sponsors:

Atma-Sphere Music Systems, Inc.

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