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 = 2n

n = number of data bits needed to specify the phase state

w = angular velocity of the carrier