ECEN4523 Commo Theory Lecture #18 28 September 2015 Dr. George Scheets n Read Chapter 4.6 – 4.7 n Problems: 4.3-8, 4.4-1, n Quiz #4, 2 October u Remote DL students < 7 October

ECEN4523 Commo Theory Lecture #19 30 September 2015 Dr. George Scheets n Read Section 5.1 n Problems: & 4 n Quiz #4, 2 October u Chapter 3 & 4 u Remote DL students < 9 October n Exam #1 Results u Hi = 100, Low = 14, Ave = 53.50, σ = A > 90, B > 75, C > 53, D > 42

Amplitude Modulation Techniques n Message in Carrier Amplitude n DSB-SC u RF BW = 2 x Baseband BW u All power in message (zero mean) n DSB-C u RF BW = 2 x Baseband BW u Most power in message (mean > 0, -Vpeak 0, -Vpeak < 0) n AM u RF BW = 2 x Baseband BW u 0 volts) n SSB u RF BW = Baseband BW

Modulation & Demodulation -B 0 +B f (Hz) Baseband fc-B fc fc+B f (Hz) XMTR RF 2fc-B 2fc 2fc+B f (Hz) RCVR Demod n Multiply by a sinusoid carrier at fc Hz n Multiply by a sync'd RCVR Local Oscillater sinusoid at fc Hz

Vestigial Sideband Modulation n Form of SSB n Don't need "brick wall" filters Easier to build n Transmit USB & part of LSB n Was used in Analog NTSC TV

Edwin Armstrong n 1890 – 1954 n IEEE Medal of Honor n Called "the most prolific and influential inventor in radio history". u Superheterodyne Receiver u Analog FM source: Wikipedia

Estimating FM BW source: Lathi & Ding