ICAO Radio Spectrum SeminarMID Office, Cairo, 4 – 6 June Frequency Assignment Planning Prepared by Torsten Jacob ICAO ANB/CNS

ICAO Radio Spectrum SeminarMID Office, Cairo, 4 – 6 June General Methodology The electromagnetic compatibility of radio equipment should be calculated by the following method: determine the desired signal level at the victim receiver front end; determine the resulting level of interference at the victim receivers front end; determine the interactive effects among wanted signals, interference and receiver characteristics for various frequency or distance separations; determine the appropriate propagation model to be used; and determine, from these data, a relationship between the frequency separation and distance separation that the interference is considered tolerable.

ICAO Radio Spectrum SeminarMID Office, Cairo, 4 – 6 June Free – Space Propagation Model The propagation loss that would occur if the antennas were replaced by isotropic antennas located in a perfectly dielectric, homogeneous, isotropic and unlimited environment, the distance between the antennas being retained (see Recommendation ITU- R P.525).

ICAO Radio Spectrum SeminarMID Office, Cairo, 4 – 6 June Aeronautical Standard Propagation Model Aeronautical standard propagation model (ASPM) is derived from the ITU-R Recommendation P.528. For distances up to the radio horizon, free space propagation is assumed. Beyond the radio horizon, a constant attenuation factor a, which depends on the frequency band under consideration, is used.

ICAO Radio Spectrum SeminarMID Office, Cairo, 4 – 6 June Radio horizon If both heights h TX and h RX are expressed in feet (ft), the distance d in Nautical Miles (NM), the Earth radius R E = 6360 km and if the atmospheric conditions are assumed to be normal (effective Earth radius factor k = 4/3), the following practical formula can be used to calculate the radio horizon:

ICAO Radio Spectrum SeminarMID Office, Cairo, 4 – 6 June Aeronautical Standard Propagation Model The propagation loss in dB between two isotropic antennas located in a perfectly dielectric, homogeneous, isotropic and unlimited environment can be calculated as follows:

ICAO Radio Spectrum SeminarMID Office, Cairo, 4 – 6 June VHF COM General principles for VHF voice communication: To protect a service with a circular operational coverage (circular service), the distances from the edge of the service to another airborne or ground transmitter must be 5 times the range of that circular service; if the other transmitter is below the radio horizon from that service edge and the radio horizon distance is also less than 5 times circular service range then radio horizon distance is to be used;

ICAO Radio Spectrum SeminarMID Office, Cairo, 4 – 6 June VHF COM General principles for VHF voice communication: To protect a service with a non-circular operational coverage area the ground or airborne transmitter of the other service must be below the radio horizon; the protection criteria for both the requested service and the existing assignment must be met for a valid assignment.

ICAO Radio Spectrum SeminarMID Office, Cairo, 4 – 6 June VHF COM

ICAO Radio Spectrum SeminarMID Office, Cairo, 4 – 6 June NM ILS localizer protection point at 25 NM distance and 6250 ft height Minimum separation between second facility and the protection point of the first facility ILS 1 ILS 2 UNDESIRED SIGNAL ILS Co-channel protection requirement for ILS localizer Minimum separation between undesired facility (ILS2) and the Protection Point of the desired facility (ILS1) of 80 NM

ICAO Radio Spectrum SeminarMID Office, Cairo, 4 – 6 June DESIRED SIGNAL INTERFERENCE VICTIM UNDESIRED SIGNAL VOR 2 INTERFERENCE SOURCE VOR 1 VOR Co-channel protection requirement Minimum uplink free-space desired-to-undesired signal ratio (D/U) of 20 dB at all points within the desired facilitys service volume

ICAO Radio Spectrum SeminarMID Office, Cairo, 4 – 6 June DESIRED SIGNAL INTERFERENCE VICTIM UNDESIRED SIGNALS DME 2 INTERFERENCE SOURCE(S) DME 1 DME Ground facilities channel assignment: Minimum uplink free-space desired-to-undesired signal ratio (D/U) at all points within the desired facilitys service volume Specific free-space D/U values are selected in order to guarantee an effective post-processing D/U of 8 dB taking into account frequency and code rejection capabilities of the interrogator receiver

ICAO Radio Spectrum SeminarMID Office, Cairo, 4 – 6 June More information More information on assignment planning principles for systems such as NDB, GBAS, HF voice and data, VDL Mode 2, 3 and 4 etc can be found at: ICAO Annex 10 ICAO RF Handbook Doc 9718 Publications of ICAO Regional Offices such as FMG Frequency Management Manual National regulations on aeronautical assignment planning

ICAO Radio Spectrum SeminarMID Office, Cairo, 4 – 6 June Thank You Any questions?