specifics on fm broadcast interference presentation by steve mitchell, uk
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SPECIFICS ON FM BROADCAST INTERFERENCE presentation by Steve Mitchell, UK. A LITTLE BIT OF HISTORY. Changes to ITU Radio Regulations recognition of potential interference to aeronautical systems studies within the ITU initial studies further enhanced studies final ITU recommendations. - PowerPoint PPT PresentationTRANSCRIPT
ICAO Regional Spectrum Seminar, Cairo, Egypt June 2006
SPECIFICS ON FM BROADCAST INTERFERENCEpresentation bySteve Mitchell, UK
ICAO Regional Spectrum Seminar, Cairo, Egypt June 2006
A LITTLE BIT OF HISTORY Changes to ITU Radio Regulations
recognition of potential interference to aeronautical systems
studies within the ITUinitial studiesfurther enhanced studiesfinal ITU recommendations
ICAO Regional Spectrum Seminar, Cairo, Egypt June 2006
GENERAL TYPES OF INTERFERENCE Four types of interference to consider
Type AA1A2
Type BB1
2 signal3signal
B2
ICAO Regional Spectrum Seminar, Cairo, Egypt June 2006
DIFFICULTIES WITH ILS/VOR/COM Extensive testing
ILS/VOR receivers3rd order intermodulationsaturation
Com receivers
ICAO Annex 10 SARPs requirements3rd order 2 signalDesensitisation
ICAO Regional Spectrum Seminar, Cairo, Egypt June 2006
DIFFICULTIES WITH GBASAND VDL 4
Testing of GBAS and VDL 4 receiverssame mechanisms apply as for ILS/VOR/COMavionics manufacturers tests above 112 MHz
split in desensitisation requirementssimilar A1and B1 criteria as ILS/VOR
ICAO Annex 10 SARPs requirements3rd order 2 signalDesensitisation
ICAO Regional Spectrum Seminar, Cairo, Egypt June 2006
Co-ordination
Why co-ordination?Between FM broadcasters
mutual sharingBetween FM broadcasters and aeronautical
avoid interference to aeronautical servicesBetween aeronautical and FM broadcasters
avoid potential problems
ICAO Regional Spectrum Seminar, Cairo, Egypt June 2006
Example of co-ordination process
Example of an approach to co-ordinationEuropean example
inside a Statedatabasescomputer toolsagreement mechanism
between StatesLEGBAC/EBU
ICAO Regional Spectrum Seminar, Cairo, Egypt June 2006
TYPE A1 CALCULATION
ICAO Regional Spectrum Seminar, Cairo, Egypt June 2006
TYPE A2 CALCULATION
ICAO Regional Spectrum Seminar, Cairo, Egypt June 2006
TYPE B1 CALCULATION2 SIGNAL
ICAO Regional Spectrum Seminar, Cairo, Egypt June 2006
TYPE B1 CALCULATION3 SIGNAL
b) Three-signal case
N1 – 20 log max (0. 4; 108. 1 – f1)
0. 4
N2 – 20 log max (0. 4; 108. 1 – f2)
0. 4
N3 – 20 log max (0. 4; 108. 1 – f3)
0. 4 K 6 – Lc S 0 (11)
where:
f1, f2, f3 : broadcasting frequencies (MHz) f1 f2, f3N1, N2, N3 : broadcasting signal levels (dBm) at the input to the aeronautical receiver for broadcasting
frequencies f1, f2 and f3 respectively
K 78 for ILS localizer and VOR
Lc : correction factor (dB) to account for changes in wanted signals, (see § 4.3.3.3)
S : 3 dB margin to take into account of the fact that the ICAO Annex 10 1998 receiver immunitycriteria equations do not provide comprehensive compatibility assessment formulae.
ICAO Regional Spectrum Seminar, Cairo, Egypt June 2006
TYPE B2 CALCULATION
ICAO Regional Spectrum Seminar, Cairo, Egypt June 2006
TRIGGER AND CUT-OFF CALCULATIONS
ICAO Regional Spectrum Seminar, Cairo, Egypt June 2006
ILS PROTECTION
ICAO Regional Spectrum Seminar, Cairo, Egypt June 2006
VOR PROTECTION
ICAO Regional Spectrum Seminar, Cairo, Egypt June 2006
PRACTICAL SOLUTIONS
WITH AUDIENCE PARTICIPATION