User Manual

Systemdesign
30
Addingnoisefromeachparallelchainisthendonethroughtheformula:
NL
Total
10 10log 10
NF1 G1+
10
-------------------------
10
NF2 G2+
10
-------------------------

10
NF
n
G
n
+
10
-----------------------
+++



=
Note:ThisisdifferentfromFriis
formulawherethenoisesourcesare
cascaded,hereeachnoisecontribution
arejustaddedinlinearandthen
convertedbacktodecibels.
Where:
NFistheno
isefigureforeachchain 
NListhetotalnoiseload
Gisthegainofthechainintotal
Whenth
esensitivityhasbeencalculateditistimetomakeaproperlinkbudgetandfindoutifthesystemwillcover
theexpectedareas.
Herear
esomeexamplesonlinkbudgetcalculationswhereyoucaninsertthenoisefigureofthesystem.These
calculationsarealsoincludedontheDAScalculatortoolandlinkbudgetsforothersystemsshouldalsobeincluded.
CDMAcanbecalculatedsimilarlytoWCDMAifthegrossdataratesetcar
ecorrected.