User's Manual
GuardianManual001‐5006‐000Rev0 20|Page
2.3 EXTENDINGTHECOVERAGEAREAWITHARELAYPOINT
TheGuardianhasaRelayPointfeaturethatallowsaunittorelaydatafromoneRFcoverageareatoanotherRF
coveragearea.Whenunitsarespreadovertwoormorecoverageareas,theusermustidentifythedevicesforming
thebackbonebetweencoverageareassoanyunitcantalk
toanyotherregardlessoftheirlocations.Therecanbe
multipleRelayPointsinthesystemextendingthecoverageoverseveralhops.
Figure2.3‐TwoCoverageAreas
Theunitformingthebackbonebetweenthecoverageareasmustbeconfiguredtorepeatallnecessary
informationfromonecoverageareatothenext.ThisunitmusthavetheRelayPointparameterenabled(See
Section6.1).
2.3.1 UNDERSTANDINGRFPATHREQUIREMENTS
Radiowavesarepropagatedwhenelectricalenergyproducedbyaradiotransmitterisconvertedintomagnetic
energybyanantenna.Magneticwavestravelthroughspace.Thereceivingantennainterceptsaverysmall
amountofthismagneticenergyandconvertsitbackintoelectricalenergythatisamplifiedbytheradioreceiver.
TheenergyreceivedbythereceiveriscalledtheReceivedSignalStrengthIndication(RSSI)andismeasuredin
dBm.
AradiomodemrequiresaminimumamountofreceivedRFsignaltooperatereliablyandprovideadequatedata
throughput.Thisistheradio’sreceiversensitivity.Inmostcases,spectrumregulatorswill
defineorlimitthe
amountofsignalthatcanbetransmittedanditwillbenotedontheFCClicense.Thisistheeffectiveisotropic
radiatedpower(EIRP
). Transmittedpowerdecayswithdistanceandotherfactorsasitmovesawayfromthe
transmittingantenna.