Assignments

Assignment 1: (maximum 6 marks)

• Q2: 1 mark for 0x1439
• Q3: 1 mark for 3 bytes, 1 mark for 0xE7, 0xB1 and 0xB3 (0 if 2 or 4 bytes)
• Q4: 1 mark for insulation thickness = 0.27mm
• Q5: 1 mark for 270 degrees or 4.7 radians
• Q6: 1 mark for -51dBW (0 if in other units)

 Assignment 2: (maximum 8 marks)

• Q3: 1 mark for first null at 19m, 1 mark for second null at 220m
• Q8: 1 mark if answer mentions crosstalk
• Q9: 1 mark for identifying the interface as a DTE
• Q10: 1 mark for correct start/stop bits; 1 for correct bit polarity; 1 for correct bit order; 1 for correct duration

Assignment 3: (maximum 6 marks)

• Q2: 1 mark for saying there would be ISI
• Q3: 1 mark for calculating Shanon capacity as 3.5 Mb/s
• Q6: 1 mark for identifying the ability to detect link failure as important in this application
• Q12: 1 mark for start flags; 1 for stuffed bit after 5 ones; 1 for ending flag

Assignment 4:

Marked out of 8.  Marks were assigned as follows:

• Q1: 1 mark for parity equal to '0'
• Q2: 1 mark for Hamming distance = 4
• Q3: 4 marks: 1 mark each for k=2, n=6, rate=1/3 and d=3
• Q5: 1 mark for: x^5 + x
• Q6: 1 mark for 1011 000

Assignment 5:

Marked out of 8:

• Q1: 1 for destination address=52:...:02, 1 for payload protocol being 0x0800=IP
• Q6: 1 for IPv4, 1 for protocol = 6 (TCP)
• Q7: 1 for correct sum = 13F29, 1 for checksum = 0xC0D5
• Q8: 1 for identifying IP address as self-assigned link-local address
• Q12: 1 for 135kHz

Pre-Lab Reports

Lab 2 Pre-Lab

• title, lab numer, name and student ID: 2 marks
• average and RMS of square, triangle and sine wave (1A, 1A, 0.500A, 0.577A, 0.636A, 0.707A ): 6 marks
• squared voltages = 1, 9; mean squared = 0.3*1 + 0.7*9 = 0.3+6.3 = 6.6; RMS = sqrt(6.3) = 2.5V: 2 marks
• 8 bits => 2^8 = 256 levels: 1 mark
• if some bins include two levels then their counts will include samples at either level, or approximately twice the value of adjacent bins that include only one level: 1 mark

Lab 4 Pre-Lab

• 1 mark for each schematic (2 total)

Lab 5 Pre-Lab

marked out of 3:

• 1 mark for a program
• 1 mark for 9.6kb/s
• 1 mark for +/- 15V output

Lab 8 Pre-Lab

marked out of 4:

• top-level protocol (1)
• display only packets matching filter expression (1)
• click on '+' or '-' (1)
• bottom window (1)

Lab 9 Pre-Lab

Marked out of 6:

• - power is A^2/2 or A^2/(2R) if R is not 1 (1)
• - -6dBm is 0.25mW
•    = A^2/2 / 600
•    A = sqrt(2*0.25E-3*600) = 0.55V (1)
• - mark = 980 Hz
• phase increment = 980 * 360 / 9600 = 36.75 degrees (0.6414 radians) per sample (1)
• - space = 1180 Hz
•   phase increment = 1180 * 360 / 9600 = 44.25 degrees (0.7723 radians) per sample (1)
• - 9600 samples/second / 300 bits/second = 32 samples/bit (1)
• - a program (1)

Lab Reports

Lab 1 Report

Marked out of 11:

• - Identification section: 2 marks (subtract 0.5 for each missing item)
• - spreadsheet with reasonably accurate results for capacitance,
•   capacitance and length  6 marks total: (2 marks if reasonable results, 1 mark for any result, 0 if no results)
• - computation of chacteristic impedance and capacitance/meter: 2 marks (1 each)
• - comparison with published values: 1 mark

Lab 2 Report

Marked out of 10:

• name & other ID: 1
• plots of the three sampled waveforms:    3
• plots of the three histograms: 3
• table with comparison of measured and computed RMS values: 3

Lab 3 Report

Marked out of 8:

• ID section: 1
• table with correct bits (0/1), polarities (+/-), start & stop: 4
• audacity and 'scope captures: 2
• program listing: 1

Lab 4 Report

Marked out of 6: (missing result: -1, suspicious results: -0.5)

For RS-232:

• - mark/space volages ~+/-10V: 1
• - output impedance >700ohm: 1
• - slew rate <30V/us: 1

For RS-422

• - independent screen captures: 1
• - differential screen capture (should be +ve and -ve): 1
• - measured a higher bit rate: 1

Lab 5 Report

Marked out of 2:

• - screen capture of with correct name: 1
• - copy of code: 1

Lab 6 Report

Marked out of 5. Marks assigned for:

• - correct ID and name of waveform file assigned: 1
• - screen capture showing two peaks (or two screen captures): 1
• - correct frequencies: 1
• - correct DTMF digit: 1
• - small difference in amplitudes: 1

Lab 7 Report

Marked out of 5:

• - ID: 1
• - spreadsheet with 4 measurements: 1
• - spreadsheet SNRs and BERs are ``in the ballpark'' (0-10 and 0.5-1E-5): 1
• - graph in log-dB format: 1
• - graph shows decreasing BER with SNR: 1

Lab 8 Report

Marked out of 4.  Marks assigned for:

• - IP address of gaia.cs.umass.edu (128.119...): 1
• - screen capture of HTTP GET and OK: 1
• - IP address of your computer (142.232...): 1
• - source and destination IP addresses stay constant: 1

Lab 9 Report

Marked out of 2:

• - screen capture of with correct name: 1
• - copy of code: 1

Final Exam

Marks were assigned as follows:

Q1:

•  1000bps: 1
•  0x58: 1
•  1: 1
•  yes: 1

Q2:

•  levels go up and down with each 1: 1
•  completely correct waveform: 1
•  correct time and voltage axis: 1

Q3:

•  use of Shannon Capacity Equation: 1
•  computing required noise power or SNR: 1
•  conversion to/from dBm: 1
•  correct answer: 1

Q4:

•  bits as correct polynomial: 1
•  division method: 1
•  correct answer: 1

Q5:

•  payload length = 50-20=30: 1
•  source IP address: 10.0.0.3: 1
•  number of routers = TTL = 58: 1

Q6:

•  max errors detected = 2: 1
•  max errors corrected = 1: 1
•  correct codeword: 1
•  reason: 1

Q7:

•  symbol rate: 1
•  bandwidth = 2x: 1
•  bandwidth = (1+alpha)*bandwidth: 1