DORDT COLLEGE ENGINEERING DEPARTMENT PROBLEM SETS (Last update: 12/18/2017 9:09 am)
|
PS # | Assigned | Due | Returned |
Problems Assigned
(In Proakis & Salehi unless otherwise noted)
|
14
|
12/07 |
12/14 |
12/18 |
Topics: Random varables, CDF, PDF, Q-function, Functions of RVs, Rand.processes, EX(x) Read Section 5.2, review Section 5.1 Do 5.9, 5.10, 5.11, 5.12 Also, please complete the course evaluation. and also this course evaluation. Hints on 5.11 Part 3) You can't use Eq. 5.1.11 (Why?) Use techniques discussed in class on 12/07 Part 4) The integral you encounter is not too hard. What is (d/dy)(exp(–y2/2σ2))? Part 5) You can use Eq. 5.1.11. Note: Problem 5.12 continues in the textbook on p. 239. |
13
|
11/30 |
12/07 |
12/12 |
Topics: Review FM, New topic: Intro to Probability Read Section 5.1 Do 4.5, 4.20, 5.1, 5.2, 5.3, 5.5 Note textbook errata on page 163. Note textbook errata on page 187, Prob. 4.20. |
12
|
11/21 |
11/30 |
12/05 |
Topics: Homework on FM, reading and class time on probability. Do 4.1, 4.2, 4.4 Note textbook errata on page 163. |
11
|
11/14 |
11/16 |
11/21 |
Topics: Review of AM modulation including the Hilbert transform. Text Section 2.6 and Chapter 3 Do 2.62, 2.65, 3.14, 3.16. |
10
|
11/02 |
11/09 |
11/15 |
Topics: SSB, QAM, VSB, Superheterodyne Read Sections 3.2.4 to end of Chapter 3 Do 3.24 and 3-A (not in textbook) Note textbook errata on page 163. |
9
|
10/31 |
11/02 |
11/15 |
Topics: SSB, Hilbert Transform Read Sections 3.2.3 and 2.6 (pages 95–98) Do 3.17 |
8
|
10/17 |
10/26 |
11/01 |
Topics: DSB-LC, Envelope Detection Read Section 3.2.2 and pages 141–143 on Envelope Detector. Do 3.11 |
7
|
10/04 |
10/12 |
10/18 |
Topics: Review Do 2.39, 2.43 part b only For solutions, see PS#5 and PS#6 |
6
|
9/26 |
10/04 |
10/10 |
Topics: AM defined, DSB-SC, DSB-LC, Spectra of and demodulation of the above Read Ch 3 Introduction through 3.2.2 Do 2.43 part (b) only, 2.44 using only part (b) of 2.43, 3.1, 3.3, 3.5, and note errata on pages 151 and 152, also. . . Use a computer to plot Eq. 3.2.6 (page 127). Let mn(t) = cos(2πfmt) and let a = 0.75, Ac = 10, fm = 440 Hz, and fc = 20 kHz. Turn that case in for a grade, but use your computer code to explore. What happens if a > 1? (try a = 1.2) What happens as fc is lowered toward fm? Be sure your plots have enough samples. You should have at least 10 samples per cycle of of cos(2πfct) and you should plot at least one cycle of mn(t). Use a computer for the plots for Problem 3.3. Octave or Matlab are recommended. Hint for Problem 2.43(b): Follow the style of the example on textbook page 53 and note that xn can be expressed without any trigonometric or complex exponential functions. Hint for Problem 2.44. Use Eq. 2.3.57 on textbook page 79. Also see pages 81 - 82. Express each answer as a synthesis of basis signals. (A finite summation in each case.) Hint for Problem 3.3 Note: On Tuesday, 9/26, we decided in class that future homework assignments will be due on Thursdays. The due date for this assignment was also changed to the Wednesday before Heartland break. |
5
|
9/19 |
9/26 |
10/03 |
Topics: Fourier Transform, Review Fourier Series Read Ch. 2, Sec 2.3, Review Sec. 2.2 Do 2.37 part 2, 2.39, 2.42, and also evaluate this integral: Also evaluate the convolution where and |
4
|
9/12 |
9/19 |
9/26 |
Topics: Signals as vectors, Fourier Series Read Ch. 2 Section 2.2 Do 2.31, 2.37 part 1 (other parts will be assigned later), find [Λ(t)sgn(t)u(t)] ★ u(t) where sgn is the signum function and u is the unit step function. The open-delta represents the unit triangle function and the star represents convolution. Hint on Problem 2.37.1: In geometric terms, let αi represent an i-dimensional vector. Let βi represent another i-dimensional vector. Then the left-hand side of the inequality is the dot-product of the two vectors. On the right-hand side of the inequality one finds the product of the lengths of the two vectors. The inequality essentially states that the dot-product of two vectors (having non-negative elements) is less than or equal to the product of the lenghts of the vectors. In communucation systems the vectors represent discrete-time signals. The "lengths" of each signal represent the square-roots of the power of each signal. Optional: For a nice review and a few more details, see how Prof. Oppenheim covers Convolution in a 50 min. lecture at MIT. Lecture 4, Convolution | MIT Hint: You can watch it in 25 min. at 2x speed! |
3
|
9/05 |
9/12 |
9/14 |
Topics: Linearity, convolution Review Ch 2 Sec. 2.1; Read Ch 2 Sec. 2.2.   Do 2.7, 2.16, 2.24, 2.34 |
2
|
8/29 |
9/05 |
9/06 |
Topics: Types of signals & systems Read: Ch 1 Sec. 1.4, Ch.2 through Sec. 2.1 Do (p. 101) 2.1 (all parts), 2.5, 2.6. Use a computer to make the plots for 2.1. Octave or Matlab are recommended. Here is a m-file to get you started. DDB's "Toolbox" files including u.m, rect.m, sinc.m and triangle.m can be downloaded as a zip archive DDB_TBX.ZIP. Hint: At the command line in Octave or Matlab type, "help sign" [enter]. Also try "help addpath", "help help" and "help exit". After file rect.m is on the path-list, note what happens when you type "help rect" in the command window. Compare to the comments in the source file, rect.m. Note errata on pages 29 and 42, and 101, 102. (On 8/31 at 2:27 PM Prof. De Boer moved Problem 2.16 to the next assignment.) |
1
| 8/29 | 8/30 | --- |
Topics: History of and overview of Comm Systems Read Chapter 1. (There is nothing to turn in.) |
Note 1) |
Homework solutions are usually available one or two class periods
after the due date. Click the "returned date" on this page to
access the solutions. If the "Returned" date is not a link (is
black, not gold) then the solution is not yet posted. Check back
later. If you click the link and get a login screen instead of
the solutions, log in using your usual courses@dordt username and
password. Then use the back icon (or alt-left-arrow on the
keyboard) twice to get back to the link on this page and click
the link again. The link only works when you are logged in to
courses@dordt.
|
Note 2) |
Problems sets shown above with no "assigned" date are
tentative. More problems might be added, expected due dates
might change, but problems shown will eventually be assigned.
|
Note 3) | If you are having difficulty reading the latest version of this page it may have to do with your browser's cached memory. Read this note on cached pages to solve the problem. |