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<br> 1. When determining causality of in Q3b, take into account that "n" can be negative. | <br> 1. When determining causality of in Q3b, take into account that "n" can be negative. | ||
<br> 2. When drawing magnitude and phase, draw for <math>\omega \in [-\pi,\pi]</math>. Remember DTFT is repetitive with period <math>2\pi</math>. So drawing phase and magnitude for one period is sufficient. | <br> 2. When drawing magnitude and phase, draw for <math>\omega \in [-\pi,\pi]</math>. Remember DTFT is repetitive with period <math>2\pi</math>. So drawing phase and magnitude for one period is sufficient. | ||
| − | <br> 3. Most common mistake was deriving phase. For example, let <math>H(\omega)=e^{j\omega}sin(\omega)</math>, <math>\angle H(\omega)=\angle e^{j\omega}+\angle sin(\omega)</math>. The key thing is to note is that <math>\angle sin(\omega) = 0</math> when <math>sin(\omega)\geq 0</math> and <math>\angle sin(\omega) = \pm \pi</math> when <math>sin(\omega)< 0</math>. Remember, <math>-1=e^{\pm j \pi}</math> | + | <br> 3. Most common mistake was deriving phase. For example, let <math>H(\omega)=e^{j\omega}sin(\omega)</math>, <math>\angle H(\omega)=\angle e^{j\omega}+\angle sin(\omega)</math>. The key thing is to note is that <math>\angle sin(\omega) = 0</math> when <math>sin(\omega)\geq 0</math> and <math>\angle sin(\omega) = \pm \pi</math> when <math>sin(\omega)< 0</math>. Remember, <math>-1=e^{\pm j \pi}</math>. |
Latest revision as of 16:22, 2 February 2009
Grading Format:
HW1 will be graded for conceptual understanding and completeness. Points will be given for work showing understanding of principles and concepts. Arithmetic mistakes therefore will not be penalized heavily. Incomplete/missing work, on the other hand, will receive large deductions.
Common mistakes on Homework 1:
1. When determining causality of in Q3b, take into account that "n" can be negative.
2. When drawing magnitude and phase, draw for $ \omega \in [-\pi,\pi] $. Remember DTFT is repetitive with period $ 2\pi $. So drawing phase and magnitude for one period is sufficient.
3. Most common mistake was deriving phase. For example, let $ H(\omega)=e^{j\omega}sin(\omega) $, $ \angle H(\omega)=\angle e^{j\omega}+\angle sin(\omega) $. The key thing is to note is that $ \angle sin(\omega) = 0 $ when $ sin(\omega)\geq 0 $ and $ \angle sin(\omega) = \pm \pi $ when $ sin(\omega)< 0 $. Remember, $ -1=e^{\pm j \pi} $.
