Computer Science 825
                         Quiz 2              Name _______________________

1. The maximum useful BAUD rate on a 10,000 hz channel is:

   a. 10,000 baud                   b. 20,000 baud

   c. 5, 000 baud                   d. Unlimited

2. a. How many signalling levels are required to transmit 64,000
      bits / second on a 4Khz bandwidth  channel.








   b. What SNR in db is necessary for this scheme to work?








3. Associate each of the following constraints with the
   "natural law" that constrains it:

   ____ a. Maximum bit rate        1. Nyquist's Law

   ____ b. Maximum baud rate       2. Westall's Law

   ____ c. Maximum # signalling    3. Shannon's Law
           levels.


4. The use of a self-clocking modulation scheme is

   a. more important for asynchronous  b. more important for synchronous
      than synchronous communication      than asynchronous communication

   c. not important for either         d. mandatory in both

5. Identify the physical layer transmission scheme used in each
   of the following interfaces:

   ____ a. Memory to U(S)ART        a. Serial and modulated carrier

   ____ b. U(S)ART to modem         b. Serial and baseband.

   ____ c. Modem to Modem           c. Parallel and modulated carrier

                                    d. Parallel and baseband.




6. Which of the following best characterizes what is meant by the
   term "asynchronous communication" as discussed in class.

   a. The sender and receiver are   b. The sender and receiver use
      completely unsynchronized.       the same physical clock.

   c. The sender and receiver use   d. The sender and receiver use
      independent clocks and resync    independent clocks and resync
      every byte time.                 every bit time.

7. In the model of synchonous transmission that we described in class

   a. the sender and receiver         b. the clocks in both USARTS
      USARTs and modems used             and modems were derived
      4 independently running            from the clock in the
      clocks.                            sender USART.

   c. the clocks in both USARTSsed    d. the clocks in both USARTS
      and modems were derived  T.        and modems were derived
      from the clock in the              from the clock in the
      sender modem.                      receiver modem.

8. In the 1200 and 9600 b.p.s. modulation schemes that we presented
   in class which one of the 3 parameters of the expression for
   a general sine wave was NOT modulated?