IP30 - ICAO AI.7 (3) - Rev. Handbook On Radio Frequency Vol. II PDF
IP30 - ICAO AI.7 (3) - Rev. Handbook On Radio Frequency Vol. II PDF
IP30 - ICAO AI.7 (3) - Rev. Handbook On Radio Frequency Vol. II PDF
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Agenda Item 7 (3)
23/07/12
SUMMARY
This paper presents the current status of the draft new Part II of the Handbook on Radio
Frequency Spectrum Requirements for Civil Aviation, (ICAO Doc 9718), developed by
the ACP WG-F.
The paper provides information on the detailed frequency assignment planning criteria for
VHF air/ground communication systems and the approval procedures of these, through
amending the current provisions in the Regional Plan for the Asia and Pacific Regions
through APANPIRG. Action required by the meeting is indicated in paragraph 4 at the
end of the paper.
Strategic Objectives
A: Safety - Enhance global civil aviation safety
C: Environmental Protection and Sustainable Development of Air Transport - Foster
harmonized and economically viable development of international civil aviation that does
not unduly harm the environment
1. Introduction/Discussion
and publishes, from time to time, lists with coordinated frequency assignments (COM Lists). These
lists are related to the Regional Air Navigation Plans.
1.2 To date, updated frequency assignment planning criteria, intended for Global use, for
VHF air/ground communication systems operating in the frequency band 117.975 137 MHz is
nearing completion.
2.1 In most Regions, the frequency assignment planning criteria that are being used,
although having been subjected to limited updates over the recent 20-25 years, are limited with
respect to the application in frequency assignment planning. The methodology that is being completed
in ICAO allows for more flexibility in frequency planning and improving the efficient use of the
available spectrum on a global basis. It also supports developing a global database of frequency
assignment as part of the Global Air Navigation Plan.
2.2 Annex 10, Volume V is subject to a revision as per State letter 2012/33 dated 24
April 2012. This revision has removed from Annex 10 most of the current guidance material and
moved this, amended as necessary, in the Handbook, Volume II. This brings together, in a single
publication, the spectrum management and the frequency management aspect of use by aviation of
aeronautical frequency bands.
2.3 The current material in the Handbook Volume II concentrates on revised frequency
assignment planning criteria for air/ground VHF communication systems (voice and data) and is
based on the work that has been completed to date by the ACP Working Group. It is expected that
Part II will be available for publication in a timely manner to support the related update to Annex 10,
Volume V, Chapter 4.
3.1 Completion of the Handbook, Volume II, is planned at the upcoming ACP Working
Group F meeting (September 2012). After review by the Air Navigation Commission, the material is
expected to be approved by ICAO and published, around the first or second quarter in 2013.
3.2 The frequency assignment planning criteria in the Handbook are to be implemented
on a Regional basis, updating or replacing most of the current material in the Air Navigation Plans.
For the APAC Region this means that the planning criteria which were agreed at the ASIA/PAC/3
Regional Air Navigation Meeting (Bangkok, 1993) will be amended through the relevant Conclusions
of the ASIA/PAC Planning and Implementation Group (APANPRIG). A detailed review of the
material in the Handbook Volume II is foreseen prior to review by the CNS/MET group in 2013 and
subsequent approval by APANPIRG. A workshop is being proposed to clarify the updated planning
criteria in the Asia/Pacific Region.
3.2 Eventually, after detailed review in the APAC Region of the new frequency
assignment planning criteria, amendments to the relevant regional provisions to implement these new
planning criteria will be developed for approval by APANPIRG. The same procedure will be applied
in other Regions.
-3- CNS/MET SG/16 IP/30 (Rev.)
Agenda Item 7 (3)
25/07/11
3.3 The updated frequency assignment planning criteria are presented in Appendix to this
paper for information of the CNS/MET SG meeting. Participants and States are invited to provide
comments. These comments can be submitted through the Secretariat of the APAC Office for review
by the ACP.
i) to note the material in the Appendix on the revised VHF COM frequency
assignment planning in the frequency band 117.975 137 MHz;
ii) to note the ongoing global developments on updating the frequency assignment
planning material for application on a Regional basis.
_____________
ICAO Handbook on radio frequency spectrum requirements for Civil Aviation Version 2012 -3
PART II Frequency assignment planning criteria for radio communication and navigation systems
Doc. 9718
ICAO Handbook on radio frequency spectrum requirements for
Civil Aviation
Part II
Frequency assignment planning criteria for aeronautical radio
communication and navigation systems
Part II of the Handbook is intended to assist States in frequency assignment planning for
aeronautical communication and navigation systems. Part II includes frequency assignment
planning criteria for VHF air/ground communication systems (voice and data). Chapters addressing
VHF/UHF radionavigation systems, non-directional beacons, HF frequencies are in preparation.
The approval of frequency assignment planning criteria rests with the Regional Planning and
Implementation Groups (PIRGs) and should be based on the provisions of Annex 10, the
material in this Handbook and relevant Regional Air Navigation Agreements.
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ICAO Handbook on radio frequency spectrum requirements for Civil Aviation Version 2012 -3
PART II Frequency assignment planning criteria for radio communication and navigation systems
Table of Contents
CHAPTER 1. GENERAL METHODOLOGY FOR COMPATIBILITY ANALYSIS.................................................5
1.1 INTRODUCTION.......................................................................................................................................................5
1.2 COMPATIBILITY MODEL ..........................................................................................................................................5
1.2.1 Compatibility assessment ..........................................................................................................................5
1.2.2 Protection of the desired signal .................................................................................................................5
1.2.3 Determination of the desired signal at the victim receiver antenna .....................................................7
1.2.4 Calculation of the undesired signal at the victim receiver antenna......................................................8
1.2.5 D/U ratio. ......................................................................................................................................................9
1.2.6 The effect of the adjacent channel rejection ...........................................................................................9
1.2.7 D/U ratio at the receiver input....................................................................................................................9
1.3 PROPAGATION MODELING .....................................................................................................................................9
1.3.1 Introduction ..................................................................................................................................................9
1.3.2 Free Space Propagation Model .............................................................................................................9
1.3.3 Aeronautical propagation curves ............................................................................................................ 12
1.3.4 Calculation of basic transmission loss when both the undesired transmitter and desired receiver
are on the ground ...................................................................................................................................................... 13
1.4 NET FILTER DISCRIMINATION (PLACEHOLDER) .................................................................................................... 14
CHAPTER 2. AERONAUTICAL VHF AIR-GROUND RADIO COMMUNICATION SYSTEMS OPERATING
IN THE BAND 117.975 137 MHZ ............................................................................................................................... 15
2.1 INTRODUCTION..................................................................................................................................................... 15
2.1.1 ICAO documents relevant to frequency assignment planning in the band 117.975-137 MHz ...... 15
2.2 INTERFERENCE MODEL ........................................................................................................................................ 15
2.2.1 General ....................................................................................................................................................... 15
2.2.2 Interference model for aeronautical frequency assignment planning ................................................ 16
2.2.3 Separation-distance ratio method ........................................................................................................... 17
2.2.4 Minimum signal level method .................................................................................................................. 19
2.2.5 The effect of the radio horizon ................................................................................................................ 23
2.2.6 Protection based on line-of sight separation ......................................................................................... 23
2.3 FREQUENCY ASSIGNMENT PLANNING CRITERIA .................................................................................................. 24
2.3.1 General planning criteria .......................................................................................................................... 24
2.3.2 Typical signal parameters ........................................................................................................................ 25
2.4 ALLOTMENT OF THE FREQUENCY BAND 117.975 137 MHZ............................................................................ 26
2.4.1 Special frequencies................................................................................................................................... 26
2.4.2 Regional allotment plans .......................................................................................................................... 27
2.5 FREQUENCY SEPARATION AND CHANNELING ...................................................................................................... 27
2.5.1 Frequency separation between VHF COM channels .......................................................................... 27
2.5.2 Protection of 25 kHz frequency assignments from 8.33 kHz assignments ...................................... 28
2.5.3 Channeling ................................................................................................................................................. 28
2.6 SERVICES AND DESIGNATED OPERATIONAL COVERAGE ..................................................................................... 28
2.6.1 Services ...................................................................................................................................................... 28
2.6.2 Coordination of special frequencies ....................................................................................................... 29
2.6.3 Table of uniform values for designated operational coverage (DOC) ............................................... 29
2.6.4 Coverage at very low angles from ground transmitter ......................................................................... 31
2.6.5 Interference from FM broadcasting stations.......................................................................................... 32
2.6.6 Co-location of facilities ............................................................................................................................. 32
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PART II Frequency assignment planning criteria for radio communication and navigation systems
List of tables
Table 2-1 Typical values for various parameters for VHF communication systems (transmitter) .................... 25
Table 2-2 Typical values for various parameters for VHF communication systems (receiver) ......................... 26
Table 2-3 Frequency allotment and special frequencies ................................................................................... 27
Table 2-4 Channeling / frequency pairing for frequencies with 25 kHz and 8.33 kHz separation ..................... 28
Table 2-5 Table of uniform designated operational coverage ........................................................................... 30
Table 2-6 Distance as function of angle above horizon ..................................................................................... 31
Table 2-7 Adjacent frequency separation distances for a mixed 25 kHz/8.33 kHz environ .............................. 41
Table 2-8 Distance to radio horizon with aircraft at maximum altitude .............................................................. 43
Table 2-9 Minimum geographical co-frequency separation distances between stations .................................. 44
Table 2-10 25 kHz guard band (channels) between DSB-AM, VDL mode 2 and VDL mode 4 (air-air) ............ 46
Table 2-11 25 kHz guard band (channels) between DSB-AM and VDL (modes 2 and 4) on the surface of an
airport ................................................................................................................................................................. 47
List of figures
Figure 1-1 Schematic diagram of the complete scenario to be analyzed ............................................................ 6
Figure 1-2 Schematic diagram of the minimum signal scenario .......................................................................... 7
Figure 1-3 Schematic diagram of the desired signal path to the receiving antenna ............................................ 7
Figure 1-4 Desired signal path when minimum field strength is specified ........................................................... 8
Figure 1-5 Schematic diagram of the undesired signal path ............................................................................... 8
Figure 1-6 Radio Horizon versus physical horizon ............................................................................................ 10
Figure 1-7 Propagation through ducting ............................................................................................................ 11
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PART II Frequency assignment planning criteria for radio communication and navigation systems
Figure A - 1 Curve sets for basic transmission loss at 125 MHz for 50% of the time for values of h1 .............. 50
Figure A - 2 Curve sets for basic transmission loss at 300 MHz for 50% of the time for values of h1 .............. 51
Figure A - 3 Curve sets for basic transmission loss at 1 200 MHz for 50% of the time for values of h1 ........... 52
Figure A - 4 Curve sets for basic transmission loss at 5 100 MHz for 50% of the time for values of h1 ........... 53
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PART II Frequency assignment planning criteria for radio communication and navigation systems
For a more detailed analysis, taking into account the aeronautical compatibility requirements, the method as
described in ITU-R Recommendation SM.337 on Frequency and distance separation may be used in some
cases. Also relevant are the provisions of ITU-R Recommendation SM.1535 on The protection of safety
services from unwanted emissions.
Note: In all cases, the co-frequency protection requirements have to be assessed, preferably through
measurements. The procedures described in Recommendation ITU-R SM.337 would allow, under specific
conditions, to develop the frequency/distance separation when the interfering signal is not co-frequency with
the desired signal while meeting the system performance requirements.
1.2.2.1.1 The first principle calculates the actual field strength of both the desired and the undesired signal at
the receiver antenna, taking into account the distance to the (desired) transmitter. On the basis of the
established D/U ratio, the maximum signal level of the undesired (interfering) signal determines in turn the
maximum level of the interfering signal, before the interference becomes harmful as shown in formula (4) in
paragraph 1.2.5.. This principle is illustrated in Figure 1-1.
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PART II Frequency assignment planning criteria for radio communication and navigation systems
antenna receiver
e.i.r.p D
input Pd input RPd
PTd Fd Gd Ld Gr Fr PTr
antenna receiver
input Pu input RPu
PTu Fu Gu e.i.r.p U Lu
where:-
F d: feeder loss for the desired transmitter (dB)
Fr: feeder loss of the receiver (dB)
F u: feeder loss for the undesired transmitter (dB)
G d: gain of the antenna of the desired transmitting system (dBi)
Gr: gain of the (desired) receiver antenna (dBi)
G u: gain of the antenna of the undesired transmitting system(dBi)
L d: propagation loss for the desired signal (dB)
L u: propagation loss for the undesired signal (dB)
PTd: output power of the desired transmitter (dBm)
PTu: output power of the undesired transmitter (dBm)
Pd power at the antenna of the desired receiver
Pu power at the antenna of the desired receiver
RPd power at the input of the desired receiver
RPu power at the input of the desired receiver
1.2.2.1.2 The second principle uses the minimum field strength at the receiver antenna (signal in space) as is
specified by ICAO for all communication and navigation systems. This minimum field strength has to be
assured throughout the designated operational coverage of the facility. Similar to the first principle described
in paragraph 1.2.2.1.1, on the basis of the established D/U ratio, the maximum signal level of the undesired
(interfering) signal can be determined, before the interference becomes harmful. This approach is more
appropriate to establish protection throughout the designated operational coverage compared to the method in
paragraph 1.2.2.1.1. This principle is shown in Figure 1-2.
1.2.2.1.3 In cases where the interactions between the desired and the undesired signal have not been
properly established (e.g. through actual measurements) protection of the desired (aeronautical) signal should
be based on securing that the undesired signal is well (6 10 dB) below the noise floor of the aeronautical
receiver.
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PART II Frequency assignment planning criteria for radio communication and navigation systems
receiver
input RPd
antenna input Pd
(as specified)
Antenna Feeder
Receiver
gain loss
PTd Fd Gd Ld Gr Fr NFDd
Receiving system
Figure 1-3 Schematic diagram of the desired signal path to the receiving antenna
The received power at the antenna of the receiver can be calculated by summing the transmitter power,
antenna gains and feeder losses as shown in formula (1)
(1)
where:
PTd output power of the desired transmitter (dBm)
F d: feeder loss for the desired transmitter (dB)
G d: gain of the desired transmitter antenna (dBi)
L d: propagation loss for the desired signal (dB)
Pd: power of the desired signal at the antenna of the receiver (dBm)
The propagation loss Ld is calculated in accordance with the appropriate propagation model as developed by
the ITU. See section 1.3 on propagation modeling and using the propagation the model to calculate the path
loss.
When the minimum desired signal level at the receiver antenna is specified and used in compatibility
calculations, the scenario as shown in Figure 1-4 applies. In this case, Pd at the antenna of the receiver is as
is specified in the relevant provisions of Annex 10.
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PART II Frequency assignment planning criteria for radio communication and navigation systems
Receiving system
Minimum specified
desired signal Pd Antenna Feeder RF filter
at antenna gain loss Detector
Gr Fr NFDd
receiver
input RPd
Figure 1-4 Desired signal path when minimum field strength is specified
( 2 ) (xx is as specified by ICAO; for the conversion from V/m to dBm see
paragraph 2.3.2)
Note: the need for calculating the signal level of the undesired signal applies to both principles as identified in
paragraphs 1.2.2.1.1 and 1.2.2.1.2 and further clarified in paragraphs 1.2.2. and 1.2.3 respectively.
Pu Receiving system
Antenna Feeder
Receiver
gain loss
The received power at the input of the receiver antenna can be calculated by summing the various transmitter
power, antenna gains and feeder losses as indicated in formula (3).
(3)
where:-
F u: feeder loss for the undesired transmitter (dB)
G u: gain of the undesired antenna (dBi)
L u: propagation loss for the undesired signal (dB)
PTu: output power of the undesired transmitter (dBW)
Pu: power of the undesired signal at the receiver antenna (dBm)
The propagation loss is calculated in accordance with the appropriate propagation model developed by the
ITU. See section 1.3 on propagation modeling and using the propagation the model to calculate the path loss.
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PART II Frequency assignment planning criteria for radio communication and navigation systems
(4)
where:
Pu = power of the undesired signal at the receiver [detector] (dBW)
Pd= power of the desired signal at the receiver [detector] (dBW)
D/U: Protection ratio (dB) as required by Annex 10 or established through measurements
Note: if the compatibility analysis is for determining compatibility between an aeronautical system and a non-
aeronautical system then a safety margin in the order of 6 10 dB should be added to the required D/U ratio.
When the frequencies are offset (i.e. the frequency of the desired signal differs from that of the undesired
signal) the adjacent channel characteristics of the desired receiver will attenuate the desired signal before it is
being processed in the receiver. The factor with which these signals are attenuated is the Adjacent Channel
Rejection (ACR). The ACR is either the ACR as specified by ICAO (typically for intra system compatibility) or
the ACR obtained by measurements (typically for inter system compatibility).
The power Pu at the antenna, as calculated with formula (3) becomes for adjacent frequencies
(5)
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PART II Frequency assignment planning criteria for radio communication and navigation systems
dielectric, homogeneous, isotropic and unlimited environment with no obstructions. The free space attenuation
or propagation loss can be calculated with formula (5)
(6)
where:
Lbf : free-space basic transmission loss (dB)
d: distance
: wavelength
Note that d and are expressed in the same unit.
The same formula can be re-written using the frequency instead of the wavelength:
(7)
where:
f: frequency (MHz)
d: distance (km).
or
(8)
where:
f: frequency (MHz)
d: distance (NM)
It should be noted that the propagation of radio waves, typical of VHF and UHF frequencies, is subject to a
number of additional conditions, compared to the free space propagation. Refraction and ducting as described
below as described below can extend the range over which this propagation model is applicable:
Refraction Gradual changes in the refractive index of the atmosphere causes the bending of radio waves to
bend slightly towards the Earth. The effect is that radio waves can propagate beyond the physical horizon to
and can be received up to a distance which is commonly referred to as the radio horizon as shown in Figure 1-
6. Along this path no other (significant) losses than the free space propagation loss between the transmitter
and the receiver has to be considered. Variations in the refractive index of the atmosphere however cause the
radio horizon to vary as well. The effect of refraction is corrected in radio propagation by calculation the
distance to the radio horizon using a 4/3 Earth radius. The 4/3 Earth radius approximation has been derived
based on a standard atmosphere at sea level and is therefore not universally applicable. However, it is very
widely used and provides a good approximation to describe the effect of radio path propagation globally.
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PART II Frequency assignment planning criteria for radio communication and navigation systems
Ducting The change in refractive index is normally linear and gradual, but under certain atmospheric
conditions a layer, of warm air may be trapped above cooler air, often over the surface of water. The result is
that the refractive index will decrease far more rapidly with height than is usual. The rapid reduction in
refractive index (and therefore dielectric constant) may cause complete bending down, as illustrated in the
Figure 1-7. The unusual atmospheric condition traps the radio waves in a duct. Extreme bending of the radio
waves between the top of the atmospheric duct and reflection of the radio waves from the surface of the Earth
may propagate the radio waves over extreme long distances (e.g. more than 500 NM). Other phenomena
such as sand storm may also cause ducting of radio waves.
Other unusual weather conditions (or other phenomena such as sand storms) can also cause ducting.
In aeronautical frequency assignment planning neither variations in the refractive index of the atmosphere
(which causes variations in the distance to the radio horizon and effectively modify the 4/3 factor)) nor the
effect of ducting is taken into account. In cases where these phenomena cause serious problems,
consideration can be given to accommodate different criteria.
In the aeronautical standard propagation model free space propagation conditions are assumed when the
transmitter and the receiver are within the distance to the radio horizon (line of (radio) sight).
The distance to the radio horizon (4/3 Earth radius) can be calculated using equation (9).
( ) (9)
where
dRH: the distance of the station to the radio horizon (NM)
hTx: the height of the transmitter above the Earths surface (feet)
Note: The same formula can be used to calculate the radio horizon of the receiver by substituting the height of
the transmitter with the height of the receiver.
Applying this formula to both the transmitter and the receiver (e.g. between an airborne transmitter and an
airborne receiver) formula (10) can be used for the calculation of the distance to the radio horizon between the
transmitter and receiver.
( ) ( 10 )
where
dRH: the radio horizon separation distance between the transmitter and receiver (NM)
hTx: the height of the transmitter above the Earths surface (feet)
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PART II Frequency assignment planning criteria for radio communication and navigation systems
hRx: the height of the receiver above the Earths surface (feet)
This propagation curves are based on empirical data of actual propagation losses for 5%, 50% and 95% time
availability. Within the radio horizon these curves are consistent with free-space path loss and allows for an
offset to account for the various time availability percentages. These curves were derived from the IF-77
model. The curves are also valid when the propagation path extends beyond the radio horizon and were used
to determine the attenuation of radio signals beyond the radio horizon.
Aeronautical frequency assignment planning is based on the curves for 50% of the time. These give a good
approximation of the free space propagation (until the radio horizon, beyond which the path losses as in
paragraph 1.3.3.1 apply.
1.3.3.1 For propagation over the horizon and based on Recommendation ITU-R P.528 curves for 125 MHz,
1 200 MHz and 5 100MHz the following path losses expressed in dB per nautical mile (a) were established:
in the band 108 137 MHz a is 0.5 dB/NM
in the band 960 1215 MHz a is 1.6 dB/NM
in the band 5030 5091 MHz a is 2.7 dB/NM
If the actual distance d between the transmitter and the receiver is less than the distance to the radio horizon,
the free space transmission loss can be calculated with formula (8).
If the actual distance d between the transmitter and the receiver is greater than the distance to the radio
horizon, (i.e. the receiver is beyond direct radio line of sight of the transmitter), the total transmission loss is
the sum of the free space transmission loss for the distance to the radio horizon and the transmission loss for
propagation beyond the radio horizon (e.g. 0.5 dB/NM for VHF frequencies as shown above. The total
transmission loss can be calculated with formula (11).
( ) ( ) ( ) ( 11 )
A Windows version of the IF 77 model is contained in the ICAO frequency assignment planning program
FREQUENCY FINDER and can be used for assessing more precise signal parameters. Normally, for radio
paths up to the radio horizon, aeronautical frequency assignment planning is based on free space propagation
loss. For the path beyond the radio horizon, as in formula (11) the transmission loss is calculated, depending
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PART II Frequency assignment planning criteria for radio communication and navigation systems
on the frequency range, as shown above in paragraph 1.3.3.1. Applying the IF-77 model may result in a more
accurate prediction of the actual radio wave propagation characteristics.
1.3.4 Calculation of basic transmission loss when both the undesired transmitter and
desired receiver are on the ground
1.3.4.1 In certain situations, both the undesired transmitter and the desired (victim) receiver can be located
on the ground (e.g. the aircraft is on the surface of the airport and may interfere with a ground receiver station
or a ground transmitter may interfere with an aircraft receiver). Applying in this case free space propagation
loss will result in unrealistic low transmission losses when free space propagation is applied. More realistic
models that should be applied in these cases is either the two-ray (or flat Earth model) or the Egli model.
1.3.4.2 Two ray or flat Earth model
To calculate the received power taking into account the effect of the ground, the two ray ground reflection
model or flat Earth model can be applied and gives a more accurate prediction of the received power
compared to the free space model with formula (12)
( 12 )
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PART II Frequency assignment planning criteria for radio communication and navigation systems
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PART II Frequency assignment planning criteria for radio communication and navigation systems
2.1.1 ICAO documents relevant to frequency assignment planning in the band 117.975-137
MHz
a. Annex 10 Volume III (Communication systems),
i. Part I (Digital data communication systems) Chapter 6 VHF air-ground digital link
ii. Part II (Voice communication systems) Chapter 2 Aeronautical Mobile Service
b. Annex 10 Volume V, Chapter 4 Utilization of frequencies above 30 MHz and Attachment A -
Considerations affecting the deployment of VHF communication frequencies
c. ICAO Regional Air Navigation Plans and relevant ICAO Regional Air Navigation Agreements
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PART II Frequency assignment planning criteria for radio communication and navigation systems
b
a
A B
du
dd
Station A Range = RA = dd
Station B Range = RB
2.2.2.3 For air/ground communications, the protection of the desired aircraft receiver (which is
communicating with a ground station) from harmful interference caused by transmissions on another aircraft
(operating on the same of an adjacent frequency) is normally the most constraining factor in securing the use
of these frequencies free from harmful interference. This model is illustrated in Figure 2-1; the schematic
diagram of this model is in Figure 2-2.
2.2.2.4 In Figure 2-1, aircraft station a that is receiving signals from the (desired) ground station A can
be interfered by transmissions from aircraft station b (or any other undesired RF source). The separation
distance between aircraft station a and aircraft station b needs to secure that level the (undesired) signals
received by aircraft a from aircraft b are sufficiently below the level of the signals received from ground
station A to prevent harmful interference. The signal ratio necessary to protect the desired signal from
harmful interference from the undesired signal is the protection ratio (D/U).
Note: in case ground station B (or both ground stations A and B) is an aeronautical broadcast station
(e.g. VOLMET) a different geometry as shown in Figure 2-1 applies. This is further described in paragraphs
2.7.2.2 and 2.7.2.3.
2.2.2.5 The signal level of the desired and the undesired signal at the aircraft antenna can be calculated
with the method as illustrated in Figure 2-2.
The level of the desired and of the undesired signal at the (desired) antenna input can be calculated with
formulas (14) and (15) as shown in Chapter 1, paragraphs 1.2.3 and 1.2.4.
The level of the desired signal at the antenna is:
( 14 )
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PART II Frequency assignment planning criteria for radio communication and navigation systems
Note: for both the desired signal and the undesired signal, the antenna gain and the feeder losses of the
receiving station are the same when the frequency of both signals is the same (co-frequency) or when both
transmitters operate on the (first) adjacent frequency (25 kHz). The ratio of the desired to the undesired signal
at the antenna is therefore the same as at the receiver input.
antenna receiver
e.i.r.p D
input Pd input RPd
PTd Fd Gd Ld Gr Fr PTr
antenna receiver
input Pu input RPu
PTu Fu Gu e.i.r.p U Lu
Figure 2-2 Desired signal and undesired signal path to desired (victim) receiver
In formula (14) Ld is the free space propagation loss for the designated operational range (DOR) of the
desired facility (A in Figure 2-1) and can be calculated with formula (8) in Chapter 1, paragraph 1.3.2:
In formula (15) Lu is the separation distance between the undesired RF source (aircraft b in Figure 2-1 and
the desired receiver (aircraft a in Figure 2-1) and can be calculated as follows:
( ) .
From this formula, the free space separation distance between the desired receiver and the undesired
transmitter can be calculated. This separation distance presents the minimum free space separation between
the desired receiver and the undesired transmitter.
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Note: equal e.i.r.p. for ground and aircraft transmitter is normally assumed in frequency assignment planning
for aeronautical air/ground communication systems. The e.i.r.p includes the transmitter output power and the
effect of cable losses and antenna gain. Tables 2-1 and 2-2 in paragraph 2.3.2 provide typical values normally
used in compatibility analyses)
The desired to undesired signal ratio (D/U) equals (formula (4) in Chapter 1); Pd and Pu are expressed
in dBm).
( )
Ld and Lu are respectively the propagation losses along the radio path from the desired transmitter and from
the undesired transmitter to the receiver and is based on free space propagation conditions. Ld is the
designated operational range of the desired facility. The free space propagation model is documented in
paragraph 1.3.2 in Chapter 1. In case the separation between the desired receiver and the undesired
transmitter is larger than the radio horizon of each station, the effect of the propagation beyond the radio
horizon needs to be considered. The effect of beyond-the-radio horizon propagation is described in paragraph
1.3.3 in Chapter 1 and paragraph 2.2.5 in this Chapter. The free space propagation loss is calculated using
formula (8) in Chapter 1, paragraph 1.3.2 as follows:
and
which brings
( ) ( 16 )
Formula (16) demonstrates that the desired to undesired (D/U) signal ratio can be expressed as the ratio
between the distance from the receiver to the undesired transmitter and the distance to the desired transmitter
under free space propagation conditions.
2.2.3.1 For aeronautical VHF air/ground voice communication systems, ICAO SARPs specify that the D/U
protection ratio for air/ground voice communication systems is 20 dB (signals in space). In areas with
frequency congestion, a D/U protection ratio of 14 dB may be used.
Substituting in formula (16) D/U = 20 gives a separation distance ratio (du/dd) of 10. In case (in free space) the
distance from the receiver to the undesired transmitter is 10 times larger than the distance to the desired
transmitter (when both the desired and the undesired transmitter radiate with the same e.i.r.p.), the signal ratio
of the desired signal to the undesired signal is 20 dB.
Substituting in formula (16) D/U = 14, gives a separation distance ratio (du/dd)of 5. In case (in free space) the
distance from the receiver to the undesired transmitter is 5 times larger than the distance to the desired
transmitter (when both the desired and the undesired transmitter radiate with the same e.i.r.p.), the signal ratio
of the desired signal to the undesired signal is 14 dB.
Note: free space propagation conditions only apply when the transmitter and the receiver are within radio line-
of-sight of each other (within the radio horizon).The separation distance ratio (du/dd) assumes equal e.i.r.p. of
both the desired and the undesired transmitter station. See section 2.3.1 for the application of the D/U ratio of
20 dB or of 14 dB.
2.2.3.2 The interference model described paragraph 2.2.2 and the distance ratio method in paragraph 2.2.3
calculate (directly or indirectly) the desired signal level at the receiver antenna (or the receiver input). This
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PART II Frequency assignment planning criteria for radio communication and navigation systems
model takes into account that when the distance between the desired transmitter and receiver is decreased,
the actual signal strength at the receiver increases and, while meeting the required D/U criteria, the distance
from the undesired (interfering) transmitter to the receiver may be decreased.
Note: The minimum signal level method, described in paragraph 2.2.4, is based on the protection of the
minimum field strength throughout the designated operational coverage of the desired service. The frequency
assignment planning constraints in this case are more restrictive.
2.2.3.3 Adjacent channel separation distance ratios can also be calculated using this method. When
calculation the adjacent channel separation, formula 21 calculates:
For adjacent channel calculations, taking into account the adjacent channel rejection ACR, this formula can be
re-written into
( )
( ) ( )
( )
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Note: These field strength levels, together with other relevant data such as typical values for ground and
airborne transmitter power, are reproduced in Tables 2 1 and 2 2 (see paragraph 2.3.2 below).
When protecting only the minimum specified field strength level (which, from the frequency assignment
protection point of view is the safest method), the method used for establishing co-frequency separation
distances does not take into account the radiated energy of the desired transmitter but requires that the
minimum specified RF signal throughout the designated operational coverage area is protected. Generally,
this method provides for better protection compared to the distance-ratio method described in paragraph 2.2.2
since it takes into account that the VHF COM antenna does not radiate in al directions the same energy (the
VHF COM antenna is not an isotropic radiator). See also paragraph 2.2.4.3 below.
2.2.4.2 The minimum signal level method is described in paragraph 1.2.2.1.2 in Chapter 1, Figure 1-2. This
method is illustrated in Figures 2-3 and 2-5. In this method, protection of the desired signal from harmful
interference requires that a signal from an undesired source (e.g. aircraft b in Figure 2-3) at the desired
receiver is sufficiently below the minimum signal level (75 V/m) of the desired signal (and NOT the actual
signal level as calculated in paragraph 2.2.2 and 2.2.3).
b
E=75 V/m a
A B
du
Station A Range = RA
Station B Range = RB
Figure 2-3 Model for establishing separation distances when minimum field strength is specified
This model also applies to calculating separation distances when the desired receiver and the undesired
transmitter are operating on adjacent frequencies. Due to the effect of RF selectivity of the desired receiver,
the minimum separation distance in this case is smaller than when they are operating on the same frequency.
The undesired (interfering) station can be an aircraft station or a ground station.
2.2.4.3 Effect of the vertical polar diagram of VHF COM antennas
2.2.4.3.1 The minimum signal level method takes into account the structure of the vertical polar antenna
diagram for the VHF COM antenna which is not radiating in all directions with the same energy, as is shown in
Figure 2-4 and in areas between the lobes, radiates less energy.
It the system design for VHF COM systems should secure that for the ground station the conditions of Annex
10 (which specify the minimum field strength) are met. Since the alternative (or simplified) model does not
take into account the actual e.i.r.p. of the desired ground station (transmitter), no separation distance ratio
criterion as described in paragraph 2.2.2.4 can be developed.
2.2.4.3.2 The minimum signal level method is recommended for use in particular when compatibility with
dissimilar systems (e.g. VHF COM voice and VDL) has to be established.
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2.2.4.4 The minimum signal level method requires that the signal level of the undesired (interfering) signal
be calculated at the antenna of the receiver. The desired signal level is 75 V/m. The D/U ratio( Pd Pu
(dBm)) is 20 (14) dB. The analysis below describes this method which is illustrated in the schematic diagram
in Figure 2-5.
receiver
input RPd
antenna
input Pd Antenna Feeder RF
Receiver
(75V/m) gain loss filtering
Gr Fr PTr
antenna receiver
input Pu input RPu
PTu Fu Gu e.i.r.p U Lu
Figure 2-5 Minimum desired signal at antenna and undesired signal path to desired (victim) receiver antenna
2.2.4.5 The (desired) signal level (Pd) at the antenna is 75 V/m (-82 dBm). The level of the undesired
signal (Pu) (from aircraft b in Figure 2-3) is calculated formula 21 in paragraph 2.2.2.3.
(at the receiver antenna)
(at the receiver antenna; Pu is for most transmitters typical 25 W)
For Pu = 25 W (44 dBm), Fu = 3dB and Gr = 0 dB,
( )
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2.2.4.6 In this scenario (D/U = 20 dB), and assuming a typical transmitter power for the undesired aircraft
transmitter of 25 W, the minimum separation distance between the desired receiver and the undesired
(aircraft) transmitter needs to secure that the transmission losses over the radio path are 143 dB.
Formula (8) in Chapter 1, paragraph 1.3.2 calculates that for a free space transmission loss of 143 dB (f = 127
MHz) a (free space) distance of 1428 NM is required. This distance is greater than the distance to the radio
horizon for aircraft at an altitude of 45000 ft. The effect of the radio horizon is described in paragraph 2.2.5.
Calculations for establishing the minimum separation distance between facilities are in section 2.7.
2.2.4.7 In case the protection ration is 14 dB (see Section 2.3.1), the required free space transmission loss
is calculated as follows:
Formula (8) in Chapter 1, paragraph 1.3.2 calculates that for a free space transmission loss (f = 127 MHz) a
(free space) separation distance of 718 NM is required. This distance is greater than the distance to the radio
horizon for aircraft at a maximum altitude of 45000 ft. The effect of the radio horizon is described in paragraph
2.2.5. Calculations for establishing the minimum separation distance between facilities are in section 2.7.
Note: When applying the minimum signal level method as described in this section, the application of a D/U of
14 dB or 20 dB has no (or a limited) effect on the minimum separation distance with a co-frequency interfering
station since in both cases the free space separation distance that is required to secure protection of the
desired signal from harmful interference is more than the sum of the distances to the radio horizon of the
respective facilities.
2.2.4.8 The minimum signal level method as described in paragraph 2.2.4.5 can also be used to calculate
the adjacent channel separation distance as follows:
(at the receiver antenna)
( ) (at the receiver antenna)
Where the total transmission loss for the undesired signal
(ACR is +60 dB for the first adjacent channel)
For Pu = 25 W (44 dBm), Fu = 3dB and Gr = 0 dB,
( )
( )
( )
For f=127 MHz and D/U=20 DB
Note: To protect the receiver to the muting threshold (5 V/m or Pd= -105.6 dBm) a minimum separation
distance of 21 NM would be required.
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PART II Frequency assignment planning criteria for radio communication and navigation systems
The minimum geographical separation distance between facilities operating on the first adjacent channel
(either 25 kHz or 8.33 kHz) is normally 10 NM. This implies that designated operational coverage areas where
adjacent channels are in use need to be separated by at least 10 NM.
For a mixed environment where both 8.33 kHz and 25 kHz channels are being used, different adjacent
channel criteria apply (see paragraph 2.7.4).
Editorial note: The EUR FMG has developed provisions for the calculation of adjacent channel geographical
separation for 8.33 kHz and 25 kHz facilities operating in a mixed environment. Additional material will be
inserted in this paragraph clarifying these provisions. Temporary, the adjacent channel criteria developed by
the EUR FMG have been inserted in paragraph 2.8
In cases where minimum required free space separation distance between the receiver and the undesired
(interfering) transmitter, as calculated with the methods in paragraph 2.2.3 or 2.2.4, is greater than the sum of
the distance to the radio horizon, the calculation of the total separation distance needs to include the
conditions applicable to the over the horizon propagation. The radio signals over the horizon are attenuated
at a much faster rate per nautical mile compared to free space propagation. This is shown in the ITU
propagation curves in Appendix A. For VHF frequencies, the attenuation beyond the radio horizon is
0.5 dB/NM. (See Chapter 1, paragraph 1.3.3.1).
In the example given in Figure 2-6, the total free space loss (propagation loss) between aircraft stations
a and b is equal to sum of the free space attenuation of the path (RHA + RHB) to which the attenuation
dBLOS needs to be added.
With formula 11 in Chapter 1, the total path loss between aircraft stations a and b as shown in Figure 2-3
can be calculated as follows:
( ) ( ) ( )
In this formula RHA, RHB and dBLOS are expressed in NM; f is expressed in MHz. RHA and RHB can be
calculated with formula (9) in Chapter 1.
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PART II Frequency assignment planning criteria for radio communication and navigation systems
This implies that when the separation distance is indeed determined by the sum of the distance to the radio
horizon of the respective facilities, the required D/U protection ratio is not met in a small area at the closest
points between the two designated operational coverage areas. It is however recognized that it is highly
unlikely that two aircraft will be at the closest point at edge of each designated operational coverage area at
the same time. The size of the small area depends on the dimensions of the designated operational coverage
of the two facilities.
2.2.6.2 In some specific cases however, as described in paragraph 2.7, the effect of propagation beyond
the radio horizon has to be considered when establishing geographical separation distances.
Note: The calculation of minimum separation distances for various air/ground communication services is
described in paragraphs 2.7 and 2.8.
( )
where
dRH = the distance of the station to the radio horizon (NM)
h = the height of the transmitter or receiver above the Earths surface (feet)
iii. the application of the minimum separation distance based on the sum of the radio horizon distance of
each facility assumes that it is highly unlikely that two aircraft will be at the closest points between and
at the maximum altitude of the frequency protected service volume of each facility
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PART II Frequency assignment planning criteria for radio communication and navigation systems
iv. details on the calculation of separation distances are in paragraph 2.7. Paragraph 2.8 contains
separation distances for the uniform designated operational coverage for aeronautical services as
identified in paragraph 2.6.
v. the separation distance shall be calculated for aircraft operating at the maximum range and maximum
height of the designated operational coverage.
vi. in cases where broadcast services (VOMET) are involved, the minimum geographical separation
distance required to obtain a protection ratio D/U of 20 dB is established relative to the ground
broadcast transmitter.
2.3.1.3 For adjacent frequency assignments, the minimum geographical separation between
facilities shall be such that points at the edge of the designated operational coverage of each facility
are separated by a distance sufficient to ensure operations free from harmful interference.
Notes:
i. the edge of the designated operational coverage is at the maximum range and maximum height.
ii. for facilities operating with 25 kHz or 8.33 kHz channel spacing, the adjacent channel separation of 10
NM has been established.
iii. protection is based on an Adjacent Channel Rejection (ACR) of 60 dB with the first assignable 25 kHz
or 8.33 kHz channel.
iv. In a mixed environment, where both 25 kHz and 8.33 kHz channel spacing is deployed, the adjacent
channel separation as shown in Table 2-6 is to be applied when making frequency assignments
Adjacent frequency emission (Transmitter) for VDL specified in Annex 10, Vol. III, Part I, paragraph 6.3.4
1st adj fr. (16 kHz bandwidth) Not specified in Annex 10 -18 dBm -18 dBm -18 dBm -18 dBm -18 dBm -18 dBm
2nd adj fr. (25 kHz bandwidth) Not specified in Annex 10 -28 dBm -28 dBm -28 dBm -28 dBm -28 dBm -28 dBm
4th adj fr. (25 kHz bandwidth) Not specified in Annex 10 -38 dBm -38 dBm -38 dBm -38 dBm -38 dBm -38 dBm
8th adj fr. (25 kHz bandwidth) Not specified in Annex 10 -43 dBm -43 dBm -43 dBm -43 dBm -43 dBm -43 dBm
16th adj fr. (25 kHz bandwidth) Not specified in Annex 10 -48 dBm -48 dBm -48 dBm -48 dBm -48 dBm -48 dBm
32nd adj fr. (25 kHz bandwidth) Not specified in Annex 10 -53.dBm -53.dBm -53.dBm -53.dBm -53.dBm -53.dBm
Table 2-1 Typical values for various parameters for VHF communication systems (transmitter)
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Conversion from input power (dBm) to field strength (V/m and v.v.) was with the following formula:
( 17 )
where:
Pr is isotropically received power (dB(W))
E is the electric field strength (dB(V/m) and
f is the frequency (GHz) (ITU-R Recommendation P.525-2 refers).
where:
Pr is the signal at receiver antenna (in space) in mW,
E is the field strength at the antenna in V/m
F is the frequency f in MHz.
[dB(V/m) = 20log(V/m)]
is expressed in dBm (power relative to 1 milliwatt)
Annex 10, Volume V includes provisions for the use of specific frequencies as follows:
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PART II Frequency assignment planning criteria for radio communication and navigation systems
123.7 MHz
129.7 MHz
130.9 MHz
122 MHz
118 MHz
137 MHz
National/International National National/International National National/International
2.4.1.2 Regional allotment plans provide for the use of the frequency band 136 137 MHz by VDL (VDL
Mode 2 and VDL Mode 4). In Europe the frequency band 136.700 137.000 MHz is reserved for VDL.
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2.5.1.1 Annex 10 stipulates that the minimum separation between assignable frequencies in the
aeronautical mobile (R) service shall be 8.33 kHz. (Annex 10, Volume V, paragraph 4.1.2.2.) This provision
recognizes that in Regions or areas where 25 KHz channel spacing provides for an adequate number of
frequency assignments to meet national and international requirements equipment designed for 25 kHz
channel spacing will continue to be used and continue to be protected. The introduction of 8.33 kHz channel
spacing in Regions or areas requires a Regional air navigation agreement for the mandatory carriage of
equipment designed for 8.33 kHz channel spacing.
2.5.1.2 Currently, 8.33 kHz frequency separation has only been introduced in the EUR Region. All other
Regions have agreed to base frequency assignment planning on 25 kHz frequency separation. This implies
that radio equipment designed for 50 kHz or 100 kHz frequency separation that may be still in operational use
is not always be protected from harmful interference that can be caused by stations operating on adjacent 25
kHz or 8.33 kHz frequencies.
2.5.3 Channeling
2.5.3.1 Normally, in aviation (e.g. in radio telephony) the frequency in use is identified by the actual
frequency. For the use of 8.33 kHz frequencies, the frequency identification for 8.33 kHz frequencies is
replaced with a channel identification that is using a number (similar to the identification of a frequency) which
is mapped to the actual frequency in use. The channel/frequency identification to be used for identifying
frequencies with a channel spacing of 8.33 kHz is as shown in Table 2 4.
Frequency Frequency
Channel #
(MHz) separation (kHz)
118.0000 25 118.000
118.0000 8.33 118.005
118.0083 8.33 118.010
118.0167 8.33 118.015
118.0250 25 118.025
118.0250 8.33 118.030
118.0333 8.33 118.035
118.0417 8.33 118.040
118.0500 25 118.050
118.0500 8.33 118.055
118.0583 8.33 118.060
118.0667 8.33 118.065
118.0750 25 118.075
118.0750 8.33 118.080
118.0833 8.33 118.085
118.0917 8.33 118.090
118.1000 25 118.100
etc.
Table 2-4 Channeling / frequency pairing for frequencies with 25 kHz and 8.33 kHz separation
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2.6.1.1 Frequency assignments are made to implement specific aeronautical services as follows:
Aerodrome
TWR Aerodrome control service
AS Aerodrome surface communications
AFIS Aerodrome flight information service
Approach
APP Approach control service
ATIS Automatic terminal information service
En route
FIS Flight information service
ACC Area control service
Other functions
A/A Air-to-air
A/G Air-to-ground
AOC Aeronautical operational control
VOLMETMeteorological broadcast for aircraft in flight
GPS VHF En-Route General Purpose System
EM Emergency
SAR Search and rescue
Approach
50 12000
APPL A/G
EUR: 25 10000
75 25000
APPI A/G
EUR: 40 EUR: 15000
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En-Route
ACCL Area 25000 Within specified area; max range155 NM** A/G
ACC-LL EUR: Area 15000 Within specified area; max range120 NM**
25000 Within specified area; max range 130 NM**
ACC-I Area A/G
EUR: 35000 Within specified area; max range 185 NM**
ACCU Area 45000 Within specified area; max range 200 NM** A/G
FIS-L Area 25000 Within specified area; max range 155 NM** A/G
45000 Within specified area; max range 200 NM**
FIS or FIS-U Area A/G
EUR: 23000 Within specified area; max range 120 NM**
VOLMET 200 45000 Maximum range 200 NM* BC
Other functions
200 45000
ATIS BC
EUR: 60 EUR: 20000
A-A 200 45000 Maximum range 200 NM** A/G
A-G 200 45000 Maximum range 200 NM** A/G
AOC 100 250 Not protected; max. range 100 NM A/G
EM N/A N/A No frequency coordination required A/G
SAR N/A N/A No frequency coordination required A/G
GPS 200 45000 Maximum range 200 NM** A/G
Table 2-5 Table of uniform designated operational coverage
Notes:
i. For designated operational coverage marked with **, see paragraph 2.6.4
ii. Different DOC areas may be specified by States
iii. DOC for AOC only provided to enable compatibility assessment when frequencies for AOC are shared
with ATC services; different DOC may be specified.
iv. For area services, no frequency protection is provides outside the specified area.
v. Unless specified by States, the DOC for A-A and A-G is assumed at 45000 ft. / 200 NM
vi. Mode: A/G: air/ground communications; BC: (ground) broadcast communications
2.6.3.2 Additional functionality concerning the use of these services in the column comments may be
added to the services as follows:
CD Clearance delivery
CTA Control area
DF Direction finding
ER Extended range
PAR Precision Approach Radar
RCAG Remote controlled air-ground communications
SR Surveillance Radar
These additions do not alter the basic service or the DOC for which the frequency is required and should be
included as a remark to the frequency assignment in the COM list in the global table of frequency
assignments.
Certain services may not require protection because they are not in operation to provide safety-of-life service
(e.g. for Gliders, Balloons). However, when these services are shared with ATC services, a compatibility
analysis is required (see also paragraph 2.7.2.5.3).
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2.6.3.3 Non-standard DOC (Range and Height) may be implemented as and when required. Reduced
DOC, where operationally acceptable, may alleviate frequency congestion.
2.6.3.4 The use of common frequencies, preferably Region wide, to satisfy requirements for specific non-
protected applications such as light aviation, gliding and balloon activities is recommended as such use
increases the efficiency in frequency assignment planning.
2.6.3.5 Frequencies for aeronautical operational control are not protected through frequency planning.
These frequencies are normally assigned on the basis of the traffic loading that is expected. (E.g. within the
same area, smaller airlines can share the same frequency for operational control purposes).
Figure 2-7 Reduction in distance to the transmitter when receiving above the horizontal plane through the ground
antenna
On the basis of the principles in 2.6.4.1, in case for certain services no actual maximum Designated
Operational Range has been specified, the maximum operational range within which frequency protection is
provided can be about 80% of the distance to the radio horizon. For certain of these services, a maximum
operational range has been incorporated in table 2-4.
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It is recognized that States may require different values for the designated operational coverage from the
uniform values in Table 2-5 for certain services.
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PART II Frequency assignment planning criteria for radio communication and navigation systems
on the same frequency (and outside the desired DOC), should be not greater than the sum of the distance to
the radio horizon from each aircraft station.
As shown in Figure 2-8, the minimum distance between the DOC of the service areas is equal to
RHA + RHB
The distance to the radio horizon can be calculated with formulas (8) or (9) in Chapter 1, paragraph 1.3.2. In
these formula, the factor hTX and or hRX is the designated operational height of the respective DOC areas.
As shown in Figure 2 8, when the ground stations (with circular coverage and the ground stations are
located approximately at the center of this coverage area) have a designated operational range of RA and RB
respectively and RHA and RB is the distance from the respective aircraft to the radio horizon, the minimum
separation distance between the ground stations is:
b
a
A B
RHA RHB
Radio horizon
Station A Range = RA
Station B Range = RB
Figure 2-8 Separation based on radio line-of-sight
As described in paragraph 2.2.2 and as per the requirements of Annex 10 the minimum required
geographical separation distance between the edges of the designated operational coverage areas can be
calculated with the separation distance ratio method as follows. This method has been implemented in Europe
[and North America].
To meet the 14 dB protection requirement, the distance between the (desired) aircraft receiver and the
(interfering) aircraft transmitter needs to be at least 5 times the distance between the (desired) aircraft receiver
and the desired ground station.
b
a
A B
5*RA or 5*RB
RA RB
In Figure 2 9 the designated operational range for ground station A is RA and for ground station B is RB.
Aircraft stations a and b operate at the closest point and at the edge of the respective DOC areas. If the
(minimum) separation distance from aircraft station a to aircraft station b is at least 5 times the distance from
aircraft station a to ground station A (5*RA) aircraft station a is protected (14 dB) from interference from aircraft
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PART II Frequency assignment planning criteria for radio communication and navigation systems
station b. Vice versa, if the distance from aircraft station b to aircraft station a is at least 5 times the distance
from aircraft station b to ground station B (5*RB) aircraft station b is protected from interference from aircraft
station a. The minimum required separation distance between the two DOC areas A and B is the largest of
The minimum separation between the ground stations (circular coverage for A and B and the ground stations
are located in the approximate center of the DOC) is the larger value of
In cases where the value (Max) [5*RA or 5*RB] is larger than the sum of the distances to the radio horizon of
each facility (RHA + RHB) as described in 2.2.5 and 2.3.3.1 above, the radio line-of-sight criterion should be
used. The minimum total required separation distance between closest points at the edges of the respective
coverage areas is therefore:
Note 1: In both cases above, the edge of the DOC area is the point where the aircraft can operate at
maximum designated operational range and height. Application of the 5 to 1 distance ratio assumes that the
e.i.r.p of both the [desired] station and the [undesired; interfering] station are the same. Where the e.i.r.p of the
transmitters is different, adjustments to the 5 to 1 distance ratio are necessary (see paragraph 1.3.4).
Note 2: The application of the 5:1 distance ratio in frequency assignment planning is not recommended for
area services or for services with circular DOC when the ground station is located well outside the center of
the circular service since in these cases the worst case where the 5.1 distance ratio needs to be met is not
always the closest point between the DOC areas considered. In addition, it should be recognized that the
benefits for efficient frequency assignment planning using the 5:1 distance ratio are marginal. Only in areas
where frequency congestion is becoming desperate, the use of the 5:1 distance ratio for frequency
assignment planning should be considered.
Note 3: in both cases above, once protection of the aircraft receiver a is secured, also the ground station is
protected from harmful interference (from aircraft station b since the ground station is well beyond the radio
horizon of aircraft station b.
2.7.2.1.2.1 For area services (such as ACC or FIS; see Table 2-5) the minimum separation distance
between the DOC of the area service (ACC, FIS) and the DOC of other service areas (which can either be an
area service or a circular service) is the distance between the closest points at the edge of the area service
and of the DOC area of the other service. This scenario is illustrated in Figure 2-15 and described in
paragraph 2.7.5
2.7.2.1.2.2 To secure protection of both services from harmful interference using radio line of sight
criterion the distance between these (closest) points shall be at least the sum of the radio horizon of each
aircraft at maximum Designated Operational Height. The distance to the radio horizon between these points
can be calculated for each point with the formulas (9) and (10) in Chapter 1, paragraph 1.3.2.
As pointed out in Note 2 to paragraph 2.7.2.1.1, the use of the 5:1 distance ratio for co-frequency assignment
planning for area services is not recommended.
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2.7.2.2.1 Broadcast services such as ATIS and VOLMET are characterized by ground-to-air transmissions
only and do not involve airborne transmissions. As a consequence, only interference from the (undesired)
ground broadcast station needs to be considered. Because to the continuing nature of the broadcast
transmissions, protection of the (desired) signal) down to the muting level of the receiver is necessary.
A VOLMET (ATIS) broadcast station normally has a maximum designated operational range is 200 NM and a
maximum designated operational height of 45000 ft. see paragraph 2.6.4 and Table 2-4). For an (undesired)
VOLMET transmitter with an e.i.r.p. of 100 W, the field strength at the (desired) aircraft, when the VOLMET
station is 15 NM beyond the radio horizon of the (desired) aircraft) will be approximately at the receiver muting
level of 5 V/m (-105.6 dBm).
The designated operational coverage for these broadcast stations is normally the maximum that can be
achieved (200 NM at flight level 450). The interference mechanism is shown in Figure 2 10.
b
a Broadcast station B
A
RHA 15 NM
RA
Broadcast station A
Figure 2-10 Interference mechanism between broadcast services
RA+RHA+15 (NM)
To secure compatibility when station B is the wanted broadcast station and aircraft B is the desired receiving
aircraft station, the minimum separation distance between the (ground) broadcast stations A and B is
RB+RHB+15 (NM)
To secure compatibility between the two broadcast stations the minimum separation distance to be maintained
between the ground broadcast stations A and B respectively is the larger value of:
The minimum separation distances between the edge of the designated operational coverage of each facility
is 15 NM.
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2.7.2.3.1 To protect an aircraft station receiving broadcasts from a ground station from another station
providing air/ground communications the mechanism as shown in Figure 2 - 11 applies
b
a
A B
RHA RHB Broadcast station B
Radio horizon
Air/ground station A
Figure 2-11 Interference mechanism between broadcast services and air/ground services
In order to protect aircraft B, which is receiving (only) broadcast information from ground broadcast station B
(e.g. VOLMET or ATIS), from interference that can be caused by transmissions from aircraft station A, the
same methodology as described in paragraph 2.7.2.1.1 applies (separation distances in case both the
undesired and the desired station provide air/ground communication services.
To protect aircraft station A from interference that can be caused by (ground ) broadcast station B, the
minimum separation between the two ground stations needs to be (see paragraph 2.7.2.2):
RA+RHA+15 NM
However, the distance to protect aircraft station B from interference from transmissions from aircraft station A
is always greater than the distance to protect aircraft station A from interference that can be caused by
broadcasting station B. Geographical separation between the facilities should be based on the method as
described in paragraph 2.7.2.1.
Along the same principles as for aircraft in flight, as described in paragraph 2.7.2.1.1, the minimum separation
distance can be calculated with the formula RHA + RHB as illustrated in Figure 2-12.
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Figure 2-12 Geometry for calculating separation distances for AS communication services
AS(D) and AS(U): Designated operational coverage for aerodrome surface communications (5 NM/100 ft.)
AC(D): Desired aircraft (antenna height 30 ft.)
AC(U): Undesired aircraft (antenna height 30 ft.)
AS(D): Desired AS ground [base] station (antenna height 100 ft.)
AS(U): Undesired AS ground [base] station (antenna height 100 ft.)
RH (AS-D) and RH(AS-U): Distance to the radio horizon from the edge of coverage (12.3 NM)
RH(AC-D) and RH(AC-U): Distance to the radio horizon from the aircraft at maximum range (6.7 NM for 30 ft.)
Using formulas (1) and (3) in Chapter 1 the required transmission loss can be calculated as
( ( ) )
For ( ) =24.6, the factor A (transmission loss beyond the radio horizon) equals 6dB. This
corresponds to a distance of 12 NM. As a result, the total minimum separation between the two ground
stations should be 36.3 NM (37 NM). Since the antenna height above the terrain of the ground station (30) is
higher than that of the aircraft station, this separation distance will protect the communications with an aircraft
(on the surface of an airport) as well as vehicles using AS frequencies.
Note: when using the two-ray propagation model (see Chapter 1, paragraph 1.3.4), the minimum separation
distance between the two ground stations would be slightly more than 25 NM.
In frequency assignment planning, the DOC for AS services is circular with a designated operational coverage
of 5 NM / 100 ft. The minimum separation distance between the DOC of two (co-frequency) AS services is
equal to the sum of the distance to the radio horizon of each station. This would provide for a co-frequency
separation distance between the ground stations of 35 NM.
If so desired, on the basis of regional agreements, the separation distances to be applied can be amended. In
addition, consideration could be given to increase the minimum separation distance to a value that would
reduce the undesired signal to below a squelch level of 5 V/m at the [airborne and ground ] receiver antenna.
However, when considering that more realistic propagation models for ground-ground propagation as in
Chapter 1, paragraph 1.3.2 will result in better protection, the separation distance of 35 NM between AS
ground stations may provide sufficient protection.
Adjacent channel protection for AS services needs to be provided by securing that the DOC of the undesired
(interfering) station is separated by at least 10 NM from the DOC of the desired station.
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Editorial note: if so desired, this paragraph can be simplified. Note that in the case of AS services, protection if
offered to the ground station as the antenna height of the ground station is greater than that of the aircraft
station on the surface of the airport.
2.7.2.5.1 Certain services are not protected from interference and in many cases, no coverage has been
determined for these services. An example is the use of frequencies for aeronautical operational control or for
special uses such as for gliders and balloons.
2.7.2.5.2 Assignment of frequencies to stations is in these cases normally determined on the basis of the
traffic loading that can be expected by the users of these -unprotected- frequencies. As long as these
frequencies are in operation exclusively for unprotected use, these assignments should not be subject to
interference calculations.
2.7.2.5.3 When these frequencies are shared with protected services, consideration needs to be given
whether the use of the unprotected frequencies may cause interference to frequencies (co- and adjacent
frequency) which do require protection from harmful interference and an assessment of potential interference
should be undertaken. This may result in a situation that while the protected service is to be protected from
interference from the unprotected service, the unprotected service is in turn also protected from interference
from the protected service. In these cases, establishing a DOC for the un-protected service is necessary.
2.7.2.5.4 In the interest of efficient frequency assignment planning it is important to realize that when
frequency assignments to unprotected services are being made, these should preferably be concentrated in
one (or more) sub-bands solely reserved for unprotected services. Where feasible, such sub-bands should be
established.
2.7.3.1 Air/ground communication services (25 kHz or 8.33 kHz frequency separation).
The minimum separation between aircraft operating on the first adjacent (25 kHz or 8.33 kHz) frequency used
in frequency assignment planning is 10 NM as illustrated in Figure 2-13. In paragraph 2.2.2.6 and 2.2.3.8
calculations for adjacent channel separation are provided. This separation distance applies to frequency
assignment for use by equipment designed for 25 kHz frequencies (channels) or for 8.33 kHz frequencies
(channels). The separation distance in cases where equipment designed for 8.33 kHz bandwidth is used in the
same area where equipment designed for 25 kHz bandwidth channels is used is described in paragraph 2.7.4.
a b
A B
10 NM
Station A Range = RA
Station B Range = RB
Figure 2-13 Adjacent frequency separation for air-ground services
The minimum separation between two ground stations operating on the first adjacent 25 kHz frequency is:
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PART II Frequency assignment planning criteria for radio communication and navigation systems
RA +10 NM +RB
This minimum separation distance prevents adjacent frequency interference between two aircraft and applies
when one (or both) aircraft stations provides air/ground communications.
2.7.3.2 Adjacent frequency separation distances between broadcast services (ATIS, VOLMET).
2.7.3.2.1 In case both ground stations are broadcast (VOLMET, ATIS) stations, the minimum adjacent
frequency separation distance between the aircraft and an unwanted (interfering) ground broadcasting station
is 13 NM as shown in Figure 2 11.
a
B
A
13 NM
Station A Range = RA
Figure 2-14 Adjacent frequency separation between broadcast services
The minimum separation between two ground broadcast stations, operating on adjacent frequency, is
RA + 13 NM
where:
RA is the designated operational range for ground broadcast station A
Similarly, for broadcast station B, the minimum separation distance between the two ground stations is
RB + 13 NM
where:
RB is the designated operational range for ground broadcast station B (not shown in Figure 2 14)
The minimum separation distance that needs to be secured between the broadcast stations A and B is the
larger value of:
(Max) RA + 13 NM or RB + 13 NM
In this case, the DOC for adjacent channels may overlap with each other.
2.7.3.3.1 In this case, two different interference mechanisms need to be analyzed as illustrated in Figures 2-
13 and 2-14. The minimum separation distance can be calculated as follows:
A - the minimum separation distance between the two ground stations to protect the aircraft station a from
interference from the (broadcasting) ground station b, as described in paragraph 2.7.4.2, is
RA +13 NM
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where
A the minimum separation distance between the two ground stations to protect the broadcast receiver
(aircraft station b) from interference from aircraft station a. With the method as described in paragraph 2.7.4.1,
the minimum distance between the aircraft stations is 10 NM. The minimum distance between the ground
stations is
RA +10 + RB
where:
RA is the designated operational range of the air-ground communication service and
RB is the designated operational range of the broadcast service
To secure protection of both services, the minimum separation between the ground stations is the larger value
of:
(Max)RA +13 NM or RA +10 + RB
2.7.4 Co and adjacent frequency consideration in a mixed environment where 8.33 kHz
and 25 kHz frequency separation is being used
Note: The following criteria have been developed by the EUR Frequency Management Group and may require
further consideration, in particular with regard to the protection of frequencies using off-set carrier (CLIMAX)
systems.
2.7.4.1 Co-frequency separation criteria should be used when the 8.33 kHz frequency and the 25 kHz
frequency are the same (e.g. channel 119.000 and 119.005 operate both on the frequency 119.000 MHz). Co-
frequency separation criteria should also be applied between an 8.33 kHz frequency and a 25 kHz frequency
which are separated by 8.33 kHz MHz. (e.g. channels 119.010 and 118.990, using frequencies 119.0083 MHz
and 118.9917 MHz respectively) are considered both co-frequency to the [25 kHz] frequency 119.000
(119.000 MHz))
2.7.4.2 At least [33] NM should be the separation distance between the edges of the DOCs when the 8.33
kHz and a 25 kHz frequencies are separated by 16.67 MHz (e.g. channels 119.015 and 118.985, using
frequencies 119.0167 MHz and 118.9833 MHz).
2.7.4.3 Note: These frequencies are considered co-frequency to the next 25 kHz frequency (e.g. co-
frequency to 119.025 MHz and 118.975 MHz respectively.
2.7.4.4 At least 10 NM should be the separation between the edges of the DOCs when the 8.33 KHz
frequency and the 25 kHz frequency are separated by 20 kHz (i.e. the same criteria as for a 25 kHz adjacent
frequency.
2.7.4.5 At least 4 NM should be the separation distance between an 8.33 kHz frequency and a 25 kHz
frequency which are separated by 25 kHz (e.g. channel 118.000 (25 kHz) and 118.030 (8.33 kHz) which use
the frequency 118.000 MHz and the frequency 118.025 MHz respectively)
2.7.4.6 Table 2 7 gives an overview of the separation distances to be maintained in a mixed 25 / 8.33 kHz
environment. The values for the adjacent frequency separation are in NM. C indicates that the co-frequency
separation criteria (line-of-sight or the 1 to 5 distance ratio needs to be applied.
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118.0000
118.0000
118.0083
118.0167
118.0250
118.0250
118.0333
118.0417
118.0500
118.0500
118.0583
118.0667
118.0750
118.0750
118.0833
118.0917
118.1000
118.1000
118.0000
118.0000
118.0000
118.000
118.005
118.010
118.015
118.025
118.030
118.035
118.040
118.050
118.055
118.060
118.065
118.075
118.080
118.085
118.090
118.100
118.105
118.0000 C C C 33 10 4
118.000
118.0000 C C 10 4
118.005
118.0083 C 10 C 10 33
118.010
118.0167 33 10 C C 10 4
118.015
118.0250 10 4 33 C C C C 33 10
118.025
118.0250 4 10 C C 10 4
118.030
118.0333 C 10 C 10 33
118.035
118.0417 33 10 C C 10 4
118.040
118.0500 4 10 4 33 C C C C 33 10
118.050
118.0500 4 10 C C 10 4
118.055
118.0583 C 10 C 10 33
118.060
118.0667 33 10 C C 10
118.065
118.0750 10 4 33 C C C C 33 10
118.075
118.0750 4 10 C C 10 4
118.080
118.0833 C 10 C 10 33
118.085
118.0917 33 10 C C 10
118.090
118.1000 10 4 33 C C C C
118.100
118.1000 4 10 C C
118.105
Table 2-7 Adjacent frequency separation distances for a mixed 25 kHz/8.33 kHz environ
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RLOS
2.7.5.2.1 The minimum separation between the designated operational coverage of two area services is
equal to the sum of the radio line-of-sight for each area service at the limit of the DOC (coverage). This
method provides frequency protection throughout the DOC of the area service. In Figure 2 15 around the
each of the area services a buffer zone equal to the distance to the radio horizon for an aircraft at maximum
altitude of the relevant DOC has been established. The minimum separation to protect the two area services
from harmful interference is established at the closest point between the service areas.
2.7.5.2.1.1 In many cases, for large designated operational coverage areas of area services, a single
ground station cannot provide coverage throughout the service area. In these cases, where required,
additional coverage is provided through installing extended range stations (forward relay). These stations can
operate on the same frequency (using the off-set carrier system as specified in Annex 10, Volume III) or on a
discrete frequency. Not in all cases full VHF coverage is provided, in particular for lower flight levels.
2.7.5.2.2 When the same frequency used by an area service is also used by a broadcasting service (which is
a circular service), the minimum separation is the larger value of the following:
a. to protect the aircraft receiver at the edge of the area coverage, the minimum distance to the ground
broadcast transmitter should be at least the distance to the radio horizon + 30 NM from the limit of the
DOC of the area service
b. the minimum distance from the aircraft broadcast receiver to the airborne transmitter at the edge of
the area service should be at least the sum of the distance to the radio horizon (radio line-of-sight) for
each aircraft. The minimum distance from the edge of the DOC of the area service to the broadcast
transmitter should be at least the sum of the distance to the radio horizon for each aircraft plus the
range of the broadcast station.
2.7.5.2.2.1 The methodology for establishing the minimum separation distances is the same as provided
in paragraphs 2.7.3 and 2.7.4. However, in order to secure protection of area services throughout the DOC,
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separation distances are measured from the limit of the DOC rather than from the ground station(s) providing
the area service.
2.7.5.3.1 The minimum separation distance between the designated operational coverage of two area
services are to be separated (at the edge of coverage) by at least 10 NM when in each of the two areas the
first adjacent frequencies is being used. (In this case, in figure 2 15 the buffer zone around the area service
is 10 NM)
2.7.5.3.2 The same condition applies when one of the services is a circular service. In this case, the minimum
separation between the edge of the designated operational coverage of the area service and the ground
station of the circular service is the range of the circular service + 10 NM
2.7.5.3.3 When the adjacent frequency used by an area service is used by a broadcasting service (which is a
circular service), the minimum separation is the larger value of the following:
a. to protect the aircraft receiver at the edge of coverage, the minimum distance to the ground broadcast
transmitter from the edge of coverage should be at least 13 NM.
b. the minimum distance from the aircraft broadcast receiving to the airborne transmitter at the edge of
the area service should be at least the sum of the distance to the radio horizon (radio line-of-sight) for
each aircraft plus 13 NM. The minimum distance from the edge of the DOC of the area service to the
broadcast transmitter should be at least 13 NM plus the range of the broadcast station.
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The minimum separation distance between the closest point of the designated operational coverage area of
each service are summarized in Table 2 9 and are in accordance with the methods described in paragraph
2.7.2. Separation distances involving air/ground communication services have been calculated as shown in
paragraph 2.7.2.1.1 and are limited to the sum of the radio horizon of each facility. When using non-uniform
values for the designated operational coverage of the services in Table 2-5, the minimum geographical
separation between the can be calculated as shown in paragraph 2.7.2.1.1 (separation distance based on
radio line-of-sight distance).
2.8.1.1 The minimum separation distance between broadcast services (VOLMET, ATIS) assumes a
designated operational coverage for these services of 260 NM / 45000 ft. See also paragraph 2.7.2.2.
TWR 156 156 338 273 212 338 273 338 273 338 338
AFIS 156 156 338 273 212 338 273 338 273 338 338
AS
25
(Note 2)
APP-U 338 338 520 455 394 520 455 520 455 520 520
APP-I
273 273 455 390 329 325 390 455 390 455 455
APP-L
INTERFER
212 212 394 329 268 394 329 394 329 394 394
ACC-U
338 338 520 455 394 520 455 520 455 520 520
(Note 1)
ACC-L
273 273 455 390 329 455 390 455 390 455 455
(Note 1)
FIS-U
338 338 520 455 394 520 455 520 455 520 520
(Note 1)
FIS-L
273 273 455 390 329 455 390 455 390 455 455
(Note 1)
VOLMET
338 338 520 455 394 520 455 520 455 15 15
ATIS
338 338 520 455 394 520 455 520 455 15 15
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distances with other services are provided. Should it be necessary to share frequencies for AS with air/ground
communication services, the minimum geographical separation distance can be calculated as shown in
paragraph 2.7.2.1.1 and assuming a designated operational coverage for aerodrome surface communications
of 5 NM/100 ft.
2.8.2.2 In the EUR Region, the table of separation distances has been developed, taking into account
i. Different values for the uniform designated operational coverage (see paragraph 2.8.3.1 and
Table 2-5.
ii. Application of the separation-distance ratio method (5:1) using the D/U protection ratio of 14 dB.
For information purposes, this table is reproduced below.
AFIS/TWR 80 125 250 200 125 328 297 261 218 328 241
TWR 125 125 250 200 125 339 308 272 229 339 252
APP-U 250 250 250 250 250 455 424 388 345 455 300
APP-I
200 200 250 200 200 412 381 345 302 412 300
APP-L
125 125 250 200 125 384 353 317 274 384 297
ACC-U
328 339 455 412 384 522 491 455 412 522 300
(Note 1)
ACC-I
297 308 424 381 353 491 460 424 381 491 300
(Note 1)
ACC-L
261 272 388 345 317 455 424 388 345 455 300
(Note 1)
ACC-LL 218 229 345 302 274 412 381 345 302 412 300
VOLMET 328 339 455 412 384 522 491 455 412 10 211
ATIS
241 252 300 300 297 300 300 300 300 211 124
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Notes:
i. Separation distances in NM.
ii. All distances in red/italics have been calculated using the 5:1 distance ratio. Other separation
distances are limited to the radio horizon.
iii. Separation distances between VOLMET and ATIS were calculated assuming an antenna height of the
VOLMET/ATIS transmitter of 65 ft. (20m)
2.9 Separation distances for VDL (VDL Mode 2 and VDL Mode 4)
2.9.1 VDL operating co-frequency with other VDL or VHF COM voice systems
2.9.1.1 The same planning criteria as used between VHF voice systems (20 dB protection ratio) should be
used. The separation criteria are those as described in paragraph 2.7.2. The designated operational coverage
for VDL Mode 2 and VDL Mode 4 facilities need to be separated from the designated operational coverage of
a co-frequency VHF-COM voice (DSB-AM) system with at least the distance to the radio horizon of each
service. .
Note: This applies also to frequency assignments between VDL facilities.
2.9.2 VDL operating on adjacent frequencies with other VDL or VHF COM voice systems
st
The 1 frequency, adjacent (25 kHz) to either a DSB-AM frequency or a VDL frequency should not be used in
the same airspace.
nd
The 2 frequency, adjacent (25 kHz) to a DSB-AM frequency should not be used in the same airspace for
VDL Mode 4.
Interference source
DSB-AM VDL 2 VDL 4
Victim DSB-AM 1 2
VDL 2 1 1 1
VDL 4 2 1 1
Table 2-10 25 kHz guard band (channels) between DSB-AM, VDL mode 2 and VDL mode 4 (air-air)
Note: The numbers in Table 4 are guard-bands (channels). The next frequency that can be used without
frequency planning constrain is 1 channel higher (e.g. a desired DSB-AM station that is interfered by a VDL
Mode 2 aircraft station requires one 25 kHz guard band.. The next frequency, 50 kHz away, can be used in
the same designated operational coverage without any frequency assignment planning constraint.
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2.9.3.2 On the basis of an analysis performed by the Aeronautical Communications Panel, the following
frequency assignment planning constraints have been developed for VDL Mode 2 and VDL Mode 4, when
operating with aircraft on the surface of an airport.
Interference source
DSB-AM VDL 2 VDL 4
Victim DSB-AM - 4 4
VDL 2 4 1 1
VDL 4 4 1 1
Table 2-11 25 kHz guard band (channels) between DSB-AM and VDL (modes 2 and 4) on the surface of an airport
2.9.3.3 Interference can occur if the frequency separation between a VDL frequency assignment (guard
band) is four channels (25 kHz) or less. In this case interference between aircraft stations can be prevented
through securing that the minimum field strength of these systems is at least 70 dBm at the antenna. Any
interference that may be caused in ground based receiving stations (i.e. not aircraft stations) can be mitigated
through using cavity filters that block in these receivers the reception of unwanted signals from transmissions
from aircraft operating on the surface of an airport.
---------------------------
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Appendices
Appendix A Aeronautical propagation curves for 125 MHz, 300 MHz, 1200 MHz and 5100 MHz
(Source: Recommendation ITU-R P.528)
Appendix B Terms and definitions
Appendix C Regional frequency allotment plans
Appendix D Regional frequency utilization table
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Appendix A
1 Figures A-1 to A-4 show median values of the basic transmission loss at the frequencies 125, 300, 1
200 and 5 100 MHz for the time availability of 50%.
2 Each figure consists of three curve sets where the upper, middle and lower sets provide h 2 values of
1000, 10 000, and 20 000 m, respectively.
3 Additional curves and further details on their application are contained in ITU-R Recommendation
P.528-3. This Recommendation also includes the curves in a tabular format (spreadsheet).
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Figure A - 1 Curve sets for basic transmission loss at 125 MHz for 50% of the time for values of h1
100
120
Basic transmission loss (dB)
a) h2 = 1 000 m
100
120 Free space
Basic transmission loss (dB)
140
h1 = 1.5 m
160
180 h1 = 15 m
200 h1 = 30 m
220 h1 = 60 m
240
h1 = 1 000 m
260
280 h1 = 10 000 m
300
0 200 400 600 800 1 000 1 200 1 400 1 600 1 800
Distance (km)
b) h2 = 10 000 m
100
Free space
120
Basic transmission loss (dB)
140 h1 = 1.5 m
160 h1 = 15 m
180 h1 = 30 m
200
h1 = 60 m
220
240 h1 = 1 000 m
260 h1 = 10 000 m
280 h1 = 20 000 m
300
0 200 400 600 800 1 000 1 200 1 400 1 600 1 800
Distance (km)
c) h2 = 20 000 m
P.0528-01-04
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Figure A - 2 Curve sets for basic transmission loss at 300 MHz for 50% of the time for values of h1
100
120
Basic transmission loss (dB)
a) h2 = 1 000 m
100
120 Free space
Basic transmission loss (dB)
140
h1 = 1.5 m
160
180 h1 = 15 m
200 h1 = 30 m
220 h1 = 60 m
240
h1 = 1 000 m
260
280 h1 = 10 000 m
300
0 200 400 600 800 1 000 1 200 1 400 1 600 1 800
Distance (km)
b) h2 = 10 000 m
100
Free space
120
Basic transmission loss (dB)
140 h1 = 1.5 m
160 h1 = 15 m
180
h1 = 30 m
200
h1 = 60 m
220
240 h1 = 1 000 m
260 h1 = 10 000 m
280
h1 = 20 000 m
300
0 200 400 600 800 1 000 1 200 1 400 1 600 1 800
Distance (km)
c) h2 = 20 000 m
P.0528-02-04
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Figure A - 3 Curve sets for basic transmission loss at 1 200 MHz for 50% of the time for values of h1
100
120
Basic transmission loss (dB)
a) h2 = 1 000 m
100
120 Free space
Basic transmission loss (dB)
140
h1 = 1.5 m
160
180 h1 = 15 m
200 h1 = 30 m
220 h1 = 60 m
240
h1 = 1 000 m
260
280 h1 = 10 000 m
300
0 200 400 600 800 1 000 1 200 1 400 1 600 1 800
Distance (km)
b) h2 = 10 000 m
100
Free space
120
Basic transmission loss (dB)
140 h1 = 1.5 m
160 h1 = 15 m
180
h1 = 30 m
200
h1 = 60 m
220
240 h1 = 1 000 m
260 h1 = 10 000 m
280 h1 = 20 000 m
300
0 200 400 600 800 1 000 1 200 1 400 1 600 1 800
Distance (km)
c) h2 = 20 000 m
P.0528-04-04
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Figure A - 4 Curve sets for basic transmission loss at 5 100 MHz for 50% of the time for values of h1
100
120
Basic transmission loss (dB)
a) h2 = 1 000 m
100
120 Free space
Basic transmission loss (dB)
140
h1 = 1.5 m
160
180 h1 = 15 m
200 h1 = 30 m
220 h1 = 60 m
240
h1 = 1 000 m
260
280 h1 = 10 000 m
300
0 200 400 600 800 1 000 1 200 1 400 1 600 1 800
Distance (km)
b) h2 = 10 000 m
100
Free space
120
Basic transmission loss (dB)
140 h1 = 1.5 m
160 h1 = 15 m
180
h1 = 30 m
200
h1 = 60 m
220
240 h1 = 1 000 m
260 h1 = 10 000 m
280 h1 = 20 000 m
300
0 200 400 600 800 1 000 1 200 1 400 1 600 1 800
Distance (km)
c) h2 = 20 000 m
P.0528-06-04
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Appendix B
Designated operational range or height (DOR or DOH) The range or height to which an aid is needed
operationally in order to provide a particular service and within which the facility is afforded frequency
protection.
Note 1 The designated value for range or height is determined in accordance with the criteria for the
deployment of the aid in question.
Note 2 The designated value for range or height forms the basis for the technical planning of aids.
Designated operational coverage (DOC) The combination of the designated operational range and the
designated operational height (e.g. 200NM/FL500 is the designated operational coverage for an aid with a
designated operational range of 500 NM and a designated operational height of 50.000 ft (Flight Level 500).
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Appendix C
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Appendix D
Regional frequency utilization table
118.0000 118.005 Not used Not used Not used TWR, APP Not used Not used
118.0000 118.000 TWR TWR TWR TWR, APP TWR TWR
118.0083 118.010 Not used Not used Not used TWR, APP Not used Not used
118.0167 118.015 Not used Not used Not used TWR, APP Not used Not used
118.0250 118.025 TWR TWR TWR TWR, APP TWR TWR
118.0250 118.030 Not used Not used Not used TWR, APP Not used Not used
118.0333 118.035 Not used Not used Not used TWR, APP Not used Not used
118.0417 118.040 Not used Not used Not used TWR, APP Not used Not used
118.0500 118.055 Not used Not used Not used TWR, APP Not used Not used
118.0500 118.050 TWR TWR TWR TWR, APP TWR TWR
118.0583 118.060 Not used Not used Not used TWR, APP Not used Not used
118.0667 118.065 Not used Not used Not used TWR, APP Not used Not used
118.0750 118.080 Not used Not used Not used TWR, APP Not used Not used
118.0750 118.075 TWR TWR TWR TWR, APP TWR TWR
118.0833 118.085 Not used Not used Not used TWR, APP Not used Not used
118.0917 118.090 Not used Not used Not used TWR, APP Not used Not used
118.1000 118.100 TWR TWR TWR TWR, APP TWR TWR
118.1000 118.105 Not used Not used Not used TWR, APP Not used Not used
118.1083 118.110 Not used Not used Not used TWR, APP Not used Not used
118.1167 118.115 Not used Not used Not used TWR, APP Not used Not used
118.1250 118.125 TWR TWR TWR TWR, APP TWR TWR
118.1250 118.130 Not used Not used Not used TWR, APP Not used Not used
118.1333 118.135 Not used Not used Not used TWR, APP Not used Not used
118.1417 118.140 Not used Not used Not used TWR, APP Not used Not used
118.1500 118.150 TWR TWR TWR TWR, APP TWR TWR
118.1500 118.155 Not used Not used Not used TWR, APP Not used Not used
118.1583 118.160 Not used Not used Not used TWR, APP Not used Not used
118.1667 118.165 Not used Not used Not used TWR, APP Not used Not used
118.1750 118.175 TWR TWR TWR TWR, APP TWR TWR
118.1750 118.180 Not used Not used Not used TWR, APP Not used Not used
118.1833 118.185 Not used Not used Not used TWR, APP Not used Not used
118.1917 118.190 Not used Not used Not used TWR, APP Not used Not used
118.2000 118.200 TWR TWR TWR TWR, APP TWR TWR
118.2000 118.205 Not used Not used Not used TWR, APP Not used Not used
118.2083 118.210 Not used Not used Not used TWR, APP Not used Not used
118.2167 118.215 Not used Not used Not used TWR, APP Not used Not used
118.2250 118.230 Not used Not used Not used TWR, APP Not used Not used
118.2250 118.225 TWR TWR TWR TWR, APP TWR TWR
118.2333 118.235 Not used Not used Not used TWR, APP Not used Not used
118.2417 118.240 Not used Not used Not used TWR, APP Not used Not used
118.2500 118.250 TWR TWR TWR TWR, APP TWR TWR
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