Kvalitet i luftbibldet og ADS-B - Forsvarets forskningsinstitutt

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Measurement 3The last measurement included a narrowband (10 MHz @ -10 dB) 1090 MHz in front of the LNA. Thefilter removes almost all signals outside the filter passband.to ADSBLNA20m28 FFI-rapport 2011/01500
Discussion and suggestionsThe measurements show that a number signals in the vicinity of 1090 MHz will enter the ADS-Breceiverfrom the LNA when operated at Mistberget. The ADS-B receiver details are not known (toFFI) and the influence of these signals on the ADS-B receiver could be estimated by the manufacturer.From the measurements it is not possible to conclude whether the high number of signals is causedby real signals or by intermodulation in the LNA. A further investigation of this could be done by abetter measurement setup and we suggest to use a high quality receiver (Rhode&Schwarz ESMC)with careful selection of filters and amplification (LNA) to investigate the signal environment.The signals in the vicinity of 1090 MHz are removed when a bandpass filter is inserted in front of theLNA, this indicate that the LNA is operating without oscillations.During the measurements it was not possible communicate with the ADS-B-unit; no verification ofthe ADS-B-unit sensitivity with filter included was possible. The ADS-B-unit could be tested with thefilter inserted.Plan for next measurementInvestigation of signals close to 1090 MHzRepeat “measurement 3”, use filters that include more frequencies around 1090 MHz, but excludethe high power broadcast transmitters. Currently available filters are 1010 – 1110 MHz(1060±100 MHz) and 710 – 1310 MHz. Identify signals in the frequency domain and investigate theseemissions in the time and modulation domain.Operate ADS-B with filterOperate the ADS-B sensor with the 1090±10 MHz and 1060±100 MHz filters and note the differenceon sensor noise level and number of replies.FFI-rapport 2011/01500 29
Page 1 and 2: FFI-rapport 2011/01500Kvalitet i lu
Page 3 and 4: SammendragInnenfor FFI-prosjekt 112
Page 5 and 6: InnholdForord 71 Innledning 91.1 Le
Page 7 and 8: ForordEtableringen av delprosjektet
Page 9 and 10: 1 InnledningFFI-prosjekt 1128, Luft
Page 11 and 12: Slike måleoppsett har likevel sin
Page 13 and 14: 3.2 Posisjon og tidEt absolutt krav
Page 15 and 16: 3.4 HastighetHastighet er ikke påk
Page 17 and 18: Figur 4.1Sann posisjonADS−B dataR
Page 19 and 20: Referanser[1] Minimum Operational P
Page 21 and 22: Appendix BDatafelter i ASTERIXI Eur
Page 23 and 24: NIC Horisontal og vertikal grense0
Page 25 and 26: B.3.2Geometrisk hastighetGeometrisk
Page 27: adar at Kongsvinger. The zero-span

Kvalitet i luftbibldet og ADS-B - Forsvarets forskningsinstitutt

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