Symbol Technologies AP-4131 manual Radio Basics, 1 S24 Network Topology

Introduction

1.2Radio Basics

Spectrum24 devices use electromagnetic waves to transmit and receive electric signals without wires. Users communicate with the network by establishing radio links between MUs and APs.

Spectrum24 products use DSSS (direct sequence spread spectrum) to transmit digital data from one device to another. Using FM, a radio signal begins with a carrier signal that provides the base or center frequency. The digital data signal is encoded onto the carriers using a DSSS “chipping algorithm”. The radio signal propagates into the air as electromagnetic waves. A receiving antenna in the path of the waves absorbs the waves as electrical signals. The receiving device demodulates the signal by reapplying the direct sequence chipping code. This demodulation results in the original digital data.

Spectrum24 uses the environment (the air and certain objects) as the transmission medium. Spectrum24 radio devices transmit in the

2.4to 2.5-GHz frequency range, a license-free range throughout most of the world. The actual range is country-dependent.

Spectrum24 devices, like other Ethernet devices, have unique, hardware- encoded Media Access Control (MAC) or IEEE addresses. MAC addresses determine the device sending or receiving data. A MAC address is a 48-bit number written as six hexadecimal bytes separated by colons.

For example:

00:A0:F8:24:9A:C8

1.2.1S24 Network Topology

The variations possible in Spectrum24 network topologies depend on the following factors:

•the AP function in the network

•the data transfer rate

•the wireless AP (WLAP) interface.

AP-4131 Access Point Product Reference Guide 3