MicrowaveradiorelaylinkZENITH80
35/52 1.2
4.1 POINTINGOFRADIORELAYLINK
Tx power must be reduced before starting pointing to avoid destruction of microwave
receiver.Maximumallowedinputsignallevelofthereceiveris‐20dBm!!
MaximumTxpowerfordifferentcombinations of antenna diameters and linkdistances areshownin
thetablebelow.Donotexceedthemaximuminputsignallevelonreceiver.
Parabolas2xAL2‐80/APR(2x52dB)
Hoplenght[km] 0,1 0,5 1,0 1,5 2,0 2,5 3,0 3,5 4,0
Txpower[dBm]‐13,0 1,2 7,4 11,1 13,8 15,9 17,7 19,3 20,6
ParabolasAL1‐80/APR(47dB)+AL2‐80/APR(52dB)
Hoplenght[km] 0,1 0,5 1,0 1,5 2,2 2,5 3,0 3,5 4,0
Txpower[dBm]‐8,0 6,2 12,4 16,1 18,8 20,9 22,7 24,3 25,6
Parabolas2xAL1‐80/APR(2x47dB)
Hoplenght[km] 0,1 0,5 1,0 1,5 2,0 2,5 3,0 3,5 4,0
Txpower[dBm]‐3,0 11,2 17,4 21,1 23,8 25,9 27,7 29,3 30,6
Table9 Max.Txpowervaluesdependingonantennasanddistance
Pointing should be done while the weather is stable and suitable without having influence of
transmitting conditions. It is better to interrupt pointing procedure and wait when meteorological
conditions(rain,snow)canhaveinfluenceonsuddenRxsignallevel
changes.
Pointing means turning antennas in both directions to achieve the best Rx signal level value. After
roughpointingwithTxpowerlimitedaccordingtotable9(ATPCswitchedoff)werecommendtodecrease
Tx power for additional 10dB for fine pointing. Optimum pointing RSSI value is between‐30 dBm
and‐
50dBm,whichguaranteesthatreceivercircuitsarenotoverloadedduringpointing.
Pointingshouldbedoneinseveralstepsinbothhorizontalandverticaldirections.Pointingshouldbe
donestepbysteponbothlink’sterminalstation,neverpointbothterminalstationssimultaneously.
Atthebeginningofpointingboth
oppositestationsmustalreadyberoughlyadjustedandswitchedon
in order to pick up their signals. Maximum Rx level must be found on the main lobe of the antenna
radiation diagram (figure 25), remember that the main lobe width is ±0,4° for AL1‐80/APR and ±0,2° for
AL2‐80/APR.
To
makepointingeasier,ODUhasthebuiltinacousticsignalizationofthesizeofreceivedsignallevel
thatcanbeswitchedonbyarotaryswitchattheuserspace(figure7).
RxLevelonthemainlobeis13dBhigherthanonthefirstsidelobes.
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