The numbers in parentheses indicate the number of marked items (1 mark
each).
Quizzes
Quiz 1 (out of 7)
Q1 (7): one mark per item below
Q1
- SNR
- maximum frequency
Q2
- byte order
- bit order
Q3
- binary value
- correct field values
- final result
Quiz 2 (out of 6)
Q1 (4)
- correct bits (high is 0)
- correct bit order
- correct data rate
- correct DTE/DCE
Q2 (2)
- calculation of normalized threshold = -2/3
- probability ~0.25
Quiz 3 (out of 7)
Q1 (2)
- differential voltage = 1 V
- common-mode voltage = 2.5 or 1.5 V
Q2(a) (3)
- average signal power = 5W
- noise power = 0.18 W
- SNR (dB) ~ 27 = 14 dB (or 1/0.43 = 3.6 dB)
Q2(b) (2)
- normalized threshold ~= +/- 2.4
- P(e) ~= 1%
Quiz 4 (out of 7)
Q1a (3)
- correct dmin
- correct detectable errors
- correct correctable errors
Q2 (1)
- correct errored bit
Q3 (2)
- correct period
- correct duration
Q4 (1):
- correct portion of frame
Labs
Pre-Lab 1 (3)
- Q1: average and rms voltage of square wave
- Q3: plot of probability density
- Q5: voltage resolution
Lab 1 Report (5)
- cover page information
- matlab/octave plot of captured sine samples
- 'scope screen capture of noise waveform
- histogram of square wave samples
- correct DMM RMS measurement for noise
Pre-Lab 2 (3)
- correct sum of digits in ID
- waveform with correct polarity and bit order
- AWG sample rate ~48 kHz
Lab 2 (2)
- screen capture with Octave waveform
- 'scope display with (correct) decoded number
Pre-Lab 3 (2)
- values <-5 and >+5
- AWG connects to RxD
Lab 3 (3)
- Octave waveform plot
- 'scope screen capture with decoded name (partial OK)
- Teraterm screen capture
Lab 4 (4)
- three 'scope screen captures showing your waveforms,
- one plot showing the computed spectra of the three line codes in dB
- a table comparing the line codes (or organized presentation thereof)
(2 if correct, 1 if partially correct, 0 if missing)
Lab 5 (4)
- script with errors corrected (e.g. correct name)
- correct number of steps (~20)
- reasonable data
- reasonably accurate graph
Lab 6 (2)
- correct descrambler schematic
- screep capture with correct waveform
Lab 7 (6)
- signal flow graphs (2)
- spreadsheet with reasonable predicted and measured BER values
- plot of BERs
- coding gain calculations
Lab 8 (4)
- hexedit screen capture showing student's name
- 'scope screen capture of the star of preamble
- wireshark screen capture showing student's name
- correct preamble frequency
Midterm Exam 1
Q1 (6)
- correct bit order
- correct bit polarities
- correct parity
- start bit
- voltages
- bit duration
Q2 (8)
- 1 marks per wrong value
Midterm Exam 2
Q1 (4)
- find t=2
- find BER=2%
- find two new t's and two new BERs
- find new average BER
Q2 (2)
- start and end flags
- bit stuffing
Q3(3)
- correct bit pattern from G(x)
- correct division
- correct conclusion
Final Exam
Q1
- probability of B = 43.75%
- information per message = 1, 1.2, 4
- entropy = 0.50 + 0.52 + 0.25 = 1.27 bits/message
Q2
- bytes required = 2
- correct method
- correct answer 62D => D8 AD
Q3
- find t~=+/-3,
- find p=1E-3
- find BER = 1E-3+1E-3 = 2E-3
Q4
- '1' common mode: 5+0/2 = 2.5 differential: 5-0=5
- '0' common mode: 5+0/2 = 2.5 differential: 0-5=-5
- no (still 10-5=5 and 5-10=-5) and yes ((10+5)/2=7.5)
Q5
- baud rate = 115.2 kHz
- yes, parity used
- even parity used
- in hex: 8B
Q6
- 10 1111 00 111 => -1 per error
Q7
- 4V/us
- threshold at 4V, noise margin=4V
Q8
- correctly identify flags
- remove stuffed bit
- all correct bits 10111 1111
Q9
- 4 bit CRC
- G(x) = 10011
- correct CRC calculation method
- correct result = 1111
Q10
- one mark deducted per error; maximum of 4 deducted
- distances: 3, 4, 3; 7, 3; 3.. dmin=3
- correct 1
- detect 2
- yes
- distances= 7, 4, 3, 4 so choose 0001111
Q11
- yes
- 4 MHz
Q12
- solve C = Blog2(1+S/N) => B = C/log2(1+S/N)
- compute B = 1E6/log2(2) = 1 MHz
Q13
- destination = 00 e0 4c 6b e4 9b
- type field = 08 00
- first byte of payload = 50
Q13
- CSMA is best for bursty channel usage
- go-back-N (0.5 for selective repeat)