ICAO Radio Spectrum Seminar MID Office, Cairo, 4 – 6 June 2006 1

Frequency Assignment Planning

Frequency Assignment Planning

Prepared by Torsten Jacob

ICAO ANB/CNS

ICAO Radio Spectrum Seminar MID Office, Cairo, 4 – 6 June 2006 2

General MethodologyGeneral 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

receiver’s 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 Seminar MID Office, Cairo, 4 – 6 June 2006 3

Free – Space Propagation Model

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).

d

Lbf

4log20

dfLbf log20log208.37

where: Lbf : free-space basic transmission loss (dB)

d : distance

: wavelength, and

d and are expressed in the same unit.

where:

f : frequency (MHz)

d : distance (NM)

ICAO Radio Spectrum Seminar MID Office, Cairo, 4 – 6 June 2006 4

Aeronautical Standard Propagation Model

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.

RxTxERH hhRkd 2

Tx Rx

k · R E

h Rx h Tx d RH

ICAO Radio Spectrum Seminar MID Office, Cairo, 4 – 6 June 2006 5

Radio horizonRadio horizon

If both heights hTX and hRX are expressed in feet (ft), the distance d in Nautical Miles (NM), the Earth radius RE = 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:

RxTxRH hhd 23.1

where:

dRH : distance to the radio horizon (NM)

hTX height of transmitting antenna above Earth’s surface (ft)

hRX height of receiving antenna above Earth’s surface (ft)

ICAO Radio Spectrum Seminar MID Office, Cairo, 4 – 6 June 2006 6

Aeronautical Standard Propagation Model

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:

RH

RH

RHRHbf dd

dd

ifdLdda

iffddL

)()(

log20log208.37)(

where:

Lbf(d) : transmission loss between transmitter and receiver as a function of distance (dB)

d : distance between transmitter and receiver (NM)

dRH : distance to the radio horizon (NM)

f : frequency (MHz)

d : distance (NM)

a : constant attenuation factor beyond radio horizon (dB/NM)

In the band 108 – 137 MHz: a = 0.5 dB/NM

In the band 960 – 1215 MHz: a = 1.6 dB/NM

In the band 5030 – 5091 MHz: a = 2.7 dB/NM

L(dRH) : free space transmission loss for the distance up to radio horizon (dB)

Tx Rx

k·RE

hRxhTx dRH

d

ICAO Radio Spectrum Seminar MID Office, Cairo, 4 – 6 June 2006 7

VHF COMVHF 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 Seminar MID Office, Cairo, 4 – 6 June 2006 8

VHF COMVHF 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 Seminar MID Office, Cairo, 4 – 6 June 2006 9

AFISTWR

16/FL30TWR

25/FL40APP

25/FL100APP

40/FL150ATIS

60/FL200APP

50/FL250VOLMET261/FL450

ACCFL150

ACCFL245

ACCFL350

ACCFL450

AFIS/TWR(16/FL30) 80 125 125 200 241* 250 328* 218* 260* 298* 328*TWR25/FL40 125 125 125 200 252* 250 339* 228* 270* 308* 339*APP25/FL100 125 125 125 200 297* 250 384* 274* 316* 353* 384*APP40/FL150 200 200 200 200 300 250 412* 301* 343* 381* 412*ATIS60/FL200 241* 252* 297* 300 114* 300 201* 300 300 300 300APP50/FL250 250 250 250 250 300 250 455* 345* 387* 425* 455*VOLMET261/450 328* 339 384* 412* 201* 455* 0* 412* 454* 491* 522*ACCFL150 218* 228* 274* 301* 300 345* 412* 301* 343* 381* 412*ACCFL245 260* 270* 316* 343* 300 387* 454* 343* 385* 423* 454*ACCFL350 298* 308* 353* 381* 300 425* 491* 381* 423* 460* 491*ACCFL450 328* 339* 384* 412* 300 455* 522* 412* 454* 491* 522*

VHF COMVHF COM

ICAO Radio Spectrum Seminar MID Office, Cairo, 4 – 6 June 2006 10

80 NM

ILS localizer protection point at 25 NM distance and6250 ft height

Minimum separation between second facilityand the protection point of the first facility

ILS 1

ILS 2

UNDESIRED SIGNAL

ILSILS 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 Seminar MID Office, Cairo, 4 – 6 June 2006 11

DESIREDSIGNAL

INTERFERENCEVICTIM

UNDESIRED SIGNAL

VOR 2

INTERFERENCE SOURCE

VOR 1

VORVOR Co-channel protection requirement

✓ Minimum uplink free-space desired-to-undesired signal ratio (D/U) of 20 dB at all points within the desired facility’s service volume

ICAO Radio Spectrum Seminar MID Office, Cairo, 4 – 6 June 2006 12

DESIREDSIGNAL

INTERFERENCEVICTIM

UNDESIREDSIGNALS

DME 2

INTERFERENCE SOURCE(S)

DME 1

DMEDME Ground facilities channel assignment:

✓ Minimum uplink free-space desired-to-undesired signal ratio (D/U) at all points within the desired facility’s 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 Seminar MID Office, Cairo, 4 – 6 June 2006 13

More informationMore 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 Seminar MID Office, Cairo, 4 – 6 June 2006 14

Thank You

Any questions?