Rounds and the Moon
CS 3240: Data-Comm and Networks
(Fall 2015)

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    Homework 16
    Due: Mon Dec 14 2015

  1. 25 points: Does this graph (I found) represent an analog or a digital signal? Why?

  2. 25 points: Does this graph (I found) represent a periodic or an aperiodic signal? Why?

  3. 25 points: Consider the sine wave y = 4 sin(.75 pi + pi * x). What are the amplitude, frequency, period, and phase of this wave? (Please include units!)

  4. 25 points: What is the formula for a sine wave with amplitude of 13 V, period of 4s, and phase shift of 2pi/3?

  5. 25 points: Draw the frequency-domain plot for the sine wave with formula: y = 6sin((1/4)pi * x).

  6. 20 points: What is the number of bits communicable per level in a digital signal with 256 amplitude levels?

  7. 20 points: What is the number of bits communicable per level in a digital signal with 415 amplitude levels?

  8. 30 points: A digital signal has 64 possible amplitude levels and a level duration of .02 seconds. What is the bit rate of this signal?

  9. 40 points: A digital signal must communicate 2.56 Mbps and has a level duration of 1/640,000 seconds. What is the minimum number of amplitude levels this signal must have?

  10. 50 points: I have a transmission medium with propagation factor 2.5. (That means the propagation speed is 2.5 times the speed of light.) If I send a signal with 128 amplitude levels and level duration of 1/100 s, what is the bit length of my signal?

  11. 0 points: You have a digital signal to communicate via baseband transmission. Since you only have a low-pass channel with limited bandwidth, you're going to approximate with an analog signal. If the bandwidth you have is 25 kHz, what will your bit rate be when approximating using only the first harmonic?

  12. 50 points: You have a digital signal to communicate via baseband transmission. Since you only have a low-pass channel with limited bandwidth, you're going to approximate with an analog signal. If the bandwidth you have is 150 MHz, what will your bit rate be when approximating using only the first harmonic?

  13. 0 points: You have a digital signal to communicate via baseband transmission. Since you only have a low-pass channel with limited bandwidth, you're going to approximate with an analog signal. If the bandwidth you have is 25 kHz, what will your bit rate be when approximating using the first, third, and fifth harmonics?

  14. 50 points: You have a digital signal to communicate via baseband transmission. Since you only have a low-pass channel with limited bandwidth, you're going to approximate with an analog signal. If the bandwidth you have is 150 MHz, what will your bit rate be when approximating using only the first, third, and fifth harmonics?

  15. 0 points: A digital signal begins with power 80 mW and is attenuated to 20 mW. Describe this change in decibels.

  16. 60 points: A digital signal begins with power 3 mW and is amplified to 6 mW. Describe this change in decibels.

  17. 70 points: A 3 Megabit message is sent from Spain to New Zealand, approximately 20,000 km away over a single, direct channel. If the channel has a propagation speed of 2 x 10^8 m/s and the bit rate over the connection is 3 Gbps, how long does it take to send the message? (You can assume there is no processing nor queueing time.)

  18. 0 points: A digital signal is being encoded using 3-level Alternate Mark Inversion (AMI) then scrambled using B8ZS. If the first bit is encoded using a positive voltage, what is the encoding for the bit string 1000000001101011? Use the symbols 0, +, and - to describe the encoding. (Not V and B.)

  19. 100 points: A digital signal is being encoded using 3-level Alternate Mark Inversion (AMI) then scrambled using B8ZS. If the first bit is encoded using a negative voltage, what is the encoding for the bit string 1101000000001001? Use the symbols 0, +, and - to describe the encoding. (Not V and B.)

  20. 0 points: A digital signal is being transformed to an analog signal using Binary ASK. If the bandwidth that's available is only 1200 Hz and the data rate, N, needs to be 900 bps, what is the highest value the factor d can have in determining the available bandwidth?

  21. 100 points: A digital signal is being transformed to an analog signal using Binary ASK. If the bandwidth that's available is only 1500 Hz and the data rate, N, needs to be 1250 bps, what is the highest value the factor d can have in determining the available bandwidth?

  22. 0 points: A digital signal is being transformed to an analog signal using Binary FSK. If the overall bandwidth that's available is only 2000 Hz, the Δf value needs to be at least 250 and the data rate, N, needs to be 900 bps, what is the highest value the factor d can have in determining the available bandwidth?

  23. 100 points: A digital signal is being transformed to an analog signal using Binary FSK. If the overall bandwidth that's available is only 2200 Hz, the Δf value needs to be at least 100 and the data rate, N, needs to be 1500 bps, what is the highest value the factor d can have in determining the available bandwidth?

  24. 100 points: A digital signal is being transformed to an analog signal using Binary PSK. If the bandwidth that's available is only 2000 Hz and the data rate, N, needs to be 1750 bps, what is the highest value the factor d can have in determining the available bandwidth?

  25. 0 points: A digital signal is being transformed to an analog signal using QPSK. If the bandwidth that's available is only 1200 Hz and the data rate, N, needs to be 1800 bps, what is the highest value the factor d can have in determining the available bandwidth?

  26. 100 points: A digital signal is being transformed to an analog signal using QPSK. If the bandwidth that's available is only 3000 Hz and the data rate, N, needs to be 4000 bps, what is the highest value the factor d can have in determining the available bandwidth?

  27. 0 points: A digital signal is being transformed to an analog signal using 4-QAM. If the bandwidth that's available is only 1200 Hz and the data rate, N, needs to be 1800 bps, what is the highest value the factor d can have in determining the available bandwidth?

  28. 100 points: A digital signal is being transformed to an analog signal using 4-QAM. If the bandwidth that's available is only 100 Hz and the data rate, N, needs to be 150 bps, what is the highest value the factor d can have in determining the available bandwidth?

  29. 0 points: A digital signal is being transformed to an analog signal using 16-QAM. If the bandwidth that's available is only 1200 Hz and the data rate, N, needs to be 3600 bps, what is the highest value the factor d can have in determining the available bandwidth?

  30. 100 points: A digital signal is being transformed to an analog signal using 16-QAM. If the bandwidth that's available is only 1000 Hz and the data rate, N, needs to be 3200 bps, what is the highest value the factor d can have in determining the available bandwidth?

    31. Total Points: 1215