1. ECEN5533 Modern Communications Theory Lecture #79 September 2014 Dr. George Scheets n Read 5.6 – 5.9 n Scan Design Problem #1 n Problems 5.14 & 5.15 n Quiz #1 (Chapter 1) [4.5 < Uncorrected Scores < 18.5] u Remote DL: No later than 11 September u Reworked Quiz due 16 September (Live) n Exam #1 u Local: 18 September u Remote DL: No later 25 September

2. ECEN5533 Modern Communications Theory Lecture #811 September 2014 Dr. George Scheets n Problems 5.16 – 5.18, 5.21 n Quiz #1 (Chapter 1) u Remote DL: No later than 11 September u Reworked Quiz due 16 September (Live) n Exam #1 u Local: 18 September u Remote DL: No later 25 September n Design Problem #1 u Due 25 September (Live) u Not Later than 2 October (DL)

3. ECEN5533 Modern Commo Theory Lesson #9 16 September 2014 Dr. George Scheets n Read 2.1 - 2.4 n Problems: 2.1, 2.7, 2.9, 2.11 n Quiz #1 (Chapter 1) u Reworked Quiz due 16 September (Live) u 1 week after return (DL) n Exam #1 (covers Chapter 1, 5, and Chapter 2 Sampling Theory) u Local: Next Time! u Remote DL: No later 25 September n Design Problem #1 u Due 25 September (Live) u Not Later than 2 October (DL) n Any graded HW is accepted late u Cost is -1 point per working day

4. Design #1: RoboCop RFP n Design an RF Public Safety Commo system for the city of Metropolis. u Info Sinks can be anywhere in city u Provide system analysis for worst case link. (0,0) (59,47) Info Source (51,39)

5. Design #1: RoboCop RFP n Configure Transmitter Site (1) u Where to locate? u Height of tower f(worst case distance) u Power Out u Uplink center frequency u Where be the electronics ? Info Source (51,39)

6. Design #1: RoboCop RFP n Path Loss is cubed not squared (4πd/λ) 3 n Antenna Gain n Two sectors n Hi Gain n Low Gain n Design for Worst Case G/Ls ratio. G Hi G Lo G Hi /L s1 G Lo /L s2

7. Design #1: RoboCop RFP n Configure Standard Receiver System u 21,200 units u Specify LNA Preamp Converts RF signal to IF or baseband u IC Amps Process RF or baseband, output baseband n All choices have $$$ impact u Many extra credit points available

8. Use a Spread Sheet!!! n Can use again (with mods) on Design 2 n Tie in costs to design choices u Can see how changes affect cost n Get a system (any system) that works u Output power > 1/4 watt & SNR > 32 dB u Anything over the minimum is Margin!!! F System delivers 1/2 w & 35 dB SNR? Increase Margin by 3 dB n Adjust parameters to reduce Costs u Get some of those extra credit points!

9. Grading n Real World RFP: u 1 team gets full credit u Everyone else gets a zero n Partial credit u Awarded on Quizzes & Tests u NOT AWARDED ON DESIGN PROJECTS! n Real world designs don't get partial credit u Either Work or They Don't n Double check your work!!! Use a spreadsheet

10. Testable Material Communication Theory LectureTextbook Homework Anything inside the circles is fair game... but overlapped areas are more likely.

11. To Maximize your score… n Budget your time n Tackle all the problems u Partial Credit is awarded n Show intermediate results n Obtain correct answer n Tests are full period, 4 pages, 100 points u Open book & notes u HW rework for < 1/2 of lost points

12. Low Noise Amps

13. System Temperature n k*T system *W n *G system = Noise power out of system n T system is referred to the front of an ideal system u SNR out = P r / k*T system *W n n A high gain device on the front end helps lower T system n Power Spectrum G X (f) u Key item for analyzing block diagrams

14. Tracking Noise Power 1/2 ∑ 10 8 ∑ Cable Amp 12.42(10 -15 ) 24.01(10 -15 ) 36.43(10 -15 ) 18.22(10 -15 ) 96.29(10 -15 ) 114.5(10 -15 ) 114.5(10 -7 ) Output SNR = 16.40 dB

15. Tracking Noise Power 10 8 ∑ 1/2 ∑ Amp Cable 12.42(10 -15 ) 96.29(10 -15 ) 108.7(10 -15 ) 108.7(10 -7 ) 24.01(10 -15 ) 108.7(10 -7 ) 54.35(10 -7 ) Output SNR = 19.64 dB

16. Multipath

17. Multipath (20 m antenna height)

18. Multipath (10 m antenna height)

19. Urban Ray Tracing Image Source: IEEE Communications Magazine

20. Effect of Ionosphere (f < 35 MHz) Line of Sight & Ground Wave

21. Ionosphere Multipath

22. "Cue Ball" Earth

23. Using Earth Contours

24. RF Link Equations... n are accurate for Line of Sight Far Field No Multipath n give a useful average for Line of Sight Far Field Multipath

25. RF Link Equations... n can give ball park results for No Line of Sight Far Field Multipath if path loss is increased n Radio Horizon is 4/3 Optical Horizon

26. Analog to Digital Conversion) Part 1... Sampler analog input x(t) discrete time output x s (t) transmitter side

27. Sampling n Ideal Sampler u Minimum Sampling Frequency > 2 * W abs n Real World Realizable Sampler u Unable to build brick wall filters u Must sample about 10% faster than 2*W abs n Output is discrete time u But contains info to reconstruct original n Voltage is still Continuous u Infinite Precision → Infinite # of bits/sample

28. Analog to Digital Conversion) Sampler analog input x(t) discrete time signal x s (t) transmitter side Source Coder bit stream

29. Analog to Digital Conversion Analog Low Pass Filter estimate of analog input discrete time signal estimate receiver side Source Decoder bit stream

30. Video Undersampling n Typical TV Video has 30 frames/second u Frame = Still Picture n Car Commercial Wheel spokes moving the wrong way Wheel spokes stationary, car moving → fs not high enough

31. 24 bit color 2 24 = 16.78 M colors

32. 256 Colors

33. 16 Colors

34. Example) Coding a Microphone Output time (sec) m(t) volts (air pressure) Energy from about 500 - 3,500 Hz.

35. A/D Convertor time (sec) m(t) volts (air pressure) Step #1) Sample the waveform at rate > 2*Max Frequency. Convert samples to a bit stream. Wired telephone voice is sampled at 8,000 samples/second. 1/8000 second

36. A/D Convertor time (sec) m(t) volts (air pressure) Step #2) Convert the sample voltages to a bit stream. Suppose m(t1) = 3.62 volts... 3.62 v t1

37. A/D Converter n Simplest technique is PCM u Wired Telephone System u Audio Compact Disks n Pulse Code Modulation Round off to N possible voltages Equal length Code word is assigned to each voltage N Typically a Power of 2 Log 2 N bits per code word

38. A/D Convertor. 1 bit/sample. time (sec) Example) N = 2. Assign 0 or 1 to voltage. 0 < Voltage < +5v, Assign Logic 1 -5v < Voltage < 0, Assign Logic 0 3.62 v, output a 1 t1 Bit Stream Out = 1111110000111...

39. A/D Convertor. 1 bit/sample. Example) N = 2. Assign 0 or 1 to voltage. Far side gets... 1111110000111 (13 samples) Need to output 13 voltages. What does a 1 represent? A 0? Receive a 1? Output +2.5 v (mid-range) Receive a 0? Output -2.5 v (mid-range) Hold the voltage until next sample 0 < Voltage < +5v, Assign Logic 1 -5v < Voltage < 0, Assign Logic 0

40. A/D Convertor. 1 bit/sample. Input to the transmitter. Output at the receiver. Considerable Round-Off error exists. +2.5 v -2.5 v

41. time (sec) Example) N = 4. Assign 00, 01, 10 or 11. 2.5 < Voltage < 5, Assign 11 0 < Voltage < 2.5, Assign 10 -2.5 < Voltage < 0, Assign 00 -5 < Voltage < -2.5, Assign 01 3.62 v, Assign 11 t1 Bit Stream Out = 11111011111100 000000101011... +2.5 v -2.5 v A/D Convertor. 2 bits/sample

42. A/D Convertor. 2 bits/sample. Input to the transmitter. Output at the receiver. Receive 11? Output 3.75v Receive 10? Output 1.25v Receive 00? Output -1.25v Receive 01? Output -3.75v Reduced Round-Off error exists. +3.75 v +1.25 v -1.25 v -3.75 v

43. Wired Telephone Local Loop n W N = 3.5 KHz Low Pass Filter Sampler F s = 8 KHz Twisted Pair Cable Nonuniform Quantize 256 levels PCM Coder 8 bits/sample 64 Kbps

44. Telephone Local Loop: Voice Decode 256 levels Hold 1/8000 sec 64 Kbps Low Pass Filter Analog Out

45. Compact Disk n W N = 20 KHz Low Pass Filter Sampler F s = 44.1 KHz Audio Source Quantize 65,536 levels Code 16 bits/sample 705.6 Kbps

46. Compact Disk Decode 65,536 levels Hold 1/44,100 sec 705.6 Kbps Low Pass Filter Analog Out

47. Audio (from NPR) n "… before a joint session of Congress for his 2nd State of the Union speech, this is actually the first…"

48. 1/8th Second of Voice

51. Sampling & Quantizing Examples  fs = 16 KHz  4096 quantiles  256 quantiles (approximate phone quality)  32 quantiles  4 quantiles (generally 2 levels used!)  4096 quantiles  fs = 16 KHz  fs = 8 KHz (some interference)  fs = 2 KHz  fs = 1 KHz