Transmitter:

System Block Description of Transmitter:
 

Block Name	Description	Signal Name	Description
A	Demultiplexer	Tx	Input binary signal
B	Digital to Analog Converter (Changes binary string into l level analog signal)	Tx1 and Tx2	Halves of Tx. Data rate decreases by scale factor 2
C	Local Oscillator. Provides cosine wave for modulation	x(t)	Multilevel analog signal with l levels of Tx1
D	Multipliers. Multiplies output signals from DAC with the cosine waves for modulation	y(t)	Multilevel analog signal with l levels of Tx2
E	90 phase shifter. Provides sine wave with same frequency as cosine wave. Necessary for QAM.	Signal inputs at F	In phase [x(t) cos w ct] and quadrature phase [y(t) sin w ct] components and added pilot signal [Ap cos w ct ]
F	Summer. Adds in phase and out of phase signals to produce resulting QAM signal.	Txout	Final QAM signal: x(t) cos w ct + y(t) sin w ct + Ap cos w ct

Receiver:

System Block Description of Receiver:
 

Block Name	Description	Signal Name	Description
A	Automatic Gain Controller. Compensates for signal attenuation	Txout=Rxin	Input binary signal
B	Bandpass Filter. Retrieves pilot signal to use to recover in-phase and quadrature phase components. Provides synchronization with Transmitter)	Rxin*sin wct and Rxin*cos w ct	Halves of Tx. Data rate decreases by scale factor 2
C	90 Phase Shifter. (Hilbert transformer. Provides sin w ct for quadrature component)	Rxx	In-phase component of received signal
D	Mulitpliers. (Retrieves in-phase and quadrature component of original signal)	Rxy	Quadrature component of received signal
E	Low Pass Filters (Removes high frequency components. Maintains baseband signal)	Rxx’ and Rxy’	In phase and quadrature digital components (quantized and encoded)
F	Analog to Digital Converters (Converts analog signal into l digital values. Parallel output)	Rxout	Final QAM received signal Rxout=Tx
G	Multiplexor. (Takes the digital in-phase and quadrature parallel components and converters into serial output signal.)