ECEN4523 Commo Theory Lecture #29 26 October 2015 Dr ECEN4523 Commo Theory Lecture #29 26 October 2015 Dr. George Scheets www.okstate.edu/elec-engr/scheets/ecen4533 Read 7.5 Problems: 7.7-2, 4, & 5 Exam #2, 30 October (Live) [Chapter 4 – Chapter 7] Remote DL students < 6 November Design Problem, due 6 November (Live) Remote DL students < 13 November

ECEN4523 Commo Theory Lecture #30 28 October 2015 Dr ECEN4523 Commo Theory Lecture #30 28 October 2015 Dr. George Scheets www.okstate.edu/elec-engr/scheets/ecen4533 Read 7.7 & 7.8 Problems: 7.7-6 & 7.8-1 & 3 Exam #2, 30 October (Live) [Chapter 4 – Chapter 7] Remote DL students < 6 November Design Problem, due 6 November (Live) Remote DL students < 13 November Quiz 5 Results High = 10, Low = 1.0, Ave = 7.13, σ = 2.69

Binary ASK 1.5 1 MHz -1.5 .00001 Two different Amplitudes are transmitted 10 cycles/.00001 seconds = 1 MHz (cycles/second) 5 cycles/symbol 200 K symbols/second = 200 K bits/second

Receiver Coherent Detection Low Pass Filter Digital Decision X cos(2πfct) Generate a frequency and phase locked sinusoid Multiply by received signal Filter out double frequency term Output is a noisy baseband symbol stream Decide which symbol was probably transmitted Requires syncing to the symbol stream Output a cleaned up version

Binary PSK 1.5 1 MHz -1.5 .00001 Two different phases are transmitted -1.5 .00001 Two different phases are transmitted 10 cycles/.00001 seconds = 1 MHz 5 cycles/symbol 200 K symbols/second = 200 K bits/second

Unfiltered 802.11b Spectrum

Binary FSK 1.5 -1.5 .00001 Two different frequencies are transmitted -1.5 .00001 Two different frequencies are transmitted Symbol #1) 5 cycles/.000005 seconds = 1 MHz Symbol #2) 10 cycles/.000005 seconds = 2 MHz 1.5 MHz Average (center) Frequency 2 symbols in .00001 seconds = 200 K symbols/second = 200 K bits/second

PSK Signal Constellations Distance along I axis is cosine Vpeak Distance along Q axis is sine Vpeak Use negative voltage if sine or cosine inverted Distance from origin is magnitude [Vcosine_peak2 + Vsine_peak2] 0.5 source: slideplayer.com

16 QAM Signal Constellations Distance along I axis is cosine Vpeak Distance along Q axis is sine Vpeak Use negative voltage if sine or cosine inverted Distance from origin is magnitude [Vcosine_peak2 + Vsine_peak2]0.5 source: waltertech426.blogspot.com/2013/08/matlab-m-ary-quadrature-signal.html & Wikipedia