Computer Science 825
                         Quiz 2              Name _______________________

1. If the BIT_RATE of a channel and the number of distinct signalling
   states V are known then the Baud rate can be determined.  Express
   the baud rate as a function of BIT_RATE and V.

   Baud rate =



2. Suppose 4 khz bandwidth line has a 20db snr.

   a. What is the maximum data rate of the channel?





   b. How many signalling levels must be used to attain it?






3. For each of the follwing pairs of transmission media identify the
   one for which a high data rate would typically be associated.

   a. Voice grade telephone   /  Private twisted pair.

   b. Baseband coax           /  Private twisted pair.

   c. Optical fiber           /  Broad band coax.

4. One way in which to modulate a sine wave carrier is called phase
   modulation what  are the other two?

   1.

   2.

5. Consider the two phase modulation based encoding schemes:
    DiBit     Phase  Shift
    00         0        45
    01        90       135
    10       180       225
    11       270       315
   Which one is used in the standard 1200 bps modem?

   Why is it better than the other?


6. Suppose a signal f(t) consists of two harmonics of frequency 1 hz
   and 2 hz. (i.e. The period = T = 1 sec and f = fundamental freq
   = 1 / T = 1 also).
   Suppose we sample incoming signal and obtain the following
   table of values:

   t      .2  |   .4   |   .6   |    .8
   -----------------------------------------
   f(t)   2   |   3    |   6    |     4

   On the back of the paper set up the linear system needed to
   determine the fourier coefficients of f.  (Hint: c = 0)