Wireless Transmission Professor: Dr. Miguel Alonso Jr.

Outline Intro Digital Modulation Techniques AM two tone FSK PSK BPSK QAM Orthogonal Frequency Division Multiplexing

Introduction Wireless comm: uses radio waves, rather than wire, to carry the signal Examples? FM and AM are examples of radio transmission, but the transmission is still analog Wireless technology is divided into three groups Fixed wireless Mobile wireless Infrared (IR) wireless

AM Two tone modulation Early form of Digital Transmission AM in which the carrier is always transmitted Amplitude modulated by two different frequencies representing either a zero or a one, usually separated by 170 Hz

Frequency Shift Keying (FSK)‏ Schemes are used for transmission of any type of binary code FSK is a form of frequency modulation in which the modulating wave shifts the output between two predetermined frequencies – usually termed mark and space The mark condition causes a shift up in frequency and the space condition causes a shift down The carrier frequency is midway between the mark and space frequencies Narrow band standard: ±42.5Hz Wide Band standard: ± 425Hz

Generating FSK

Phase Shift Keying Incoming data causes the p Vo(t) = V * sin(w(t) + 2*pi*(i – 1)/M )‏ i = 1, 2,... M M = 2 n n = number of data bits needed to specify the phase state w = angular velocity of the carrier