CalAmp Guardian-100 User Manual

CalAmp Guardian-100 User Manual Manual pdf 20 page image

001-5006-000_FCC.docx Page 20The unit forming the backbone between the coverage areas must be configured to repeat allnecessary information from one coverage area to the next. This unit must have the RelayPoint parameter enabled (See Section 6.1).2.3.1 Understanding RF Path RequirementsRadio waves are propagated when electrical energy produced by a radio transmitter isconverted into magnetic energy by an antenna. Magnetic waves travel through space. Thereceiving antenna intercepts a very small amount of this magnetic energy and converts itback into electrical energy that is amplified by the radio receiver. The energy received bythe receiver is called the Received Signal Strength Indication (RSSI) and is measured indBm.A radio modem requires a minimum amount of received RF signal to operate reliably andprovide adequate data throughput. This is the radio’s receiver sensitivity. In most cases,spectrum regulators will define or limit the amount of signal that can be transmitted and itwill be noted on the FCC license. This is the effective isotropic radiated power (EIRP).Transmitted power decays with distance and other factors as it moves away from thetransmitting antenna.2.4 SITE SELECTION AND SITE SURVEY2.4.1 Site SelectionFor a successful installation, careful thought must be given to selecting the site for eachradio. Suitable sites should provide the following: Protection from direct weather exposure A source of adequate and stable primary power Suitable entrances for antenna, interface, or other cabling Antenna location with an unobstructed transmission path to all remote radios in thesystemThese requirements can be quickly determined in most cases.