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the MLS channel may be selected from Group 3, 4 or 5;
b) when an MLSDME is intended to operate on a runway
without the coexistence of an ILS, the DME channel to
be used shall preferably be selected from Group 3, 4 or 5.
4.3.3.2 Groups 6 to 10. These DME channels shall be
permitted to be used on the basis of a regional agreement when
they have become applicable in accordance with the conditions
specified at 4.3.2.
4.3.4 Recommendation.- Coordination of regional DME
channel assignments should be effected through ICAO.
4.4 Utilization in the band 5 030.4 - 5 150.0 MHz
Note I.- Guidance material on the frequency protection
planning of MLS facilities is contained in Attachment G to
Volume I.
Note 2.- Guidance on determining coordination distances
between MLS facilities and ground stations providing feeder
links to non-geostationary mobile satellites is contained in
ITU-R Recommendation S. 1342.
4.4.1 The MLS channels shall be selected from Table A,
Chapter 3 of Volume I.
4.4.2 For regional planning purposes MLS channels shall
be selected in accordance with the conditions specified in 4.3.3
for the associated DME facility.
4.4.3 Channel assignments in addition to those specified in
4.4.1 shall be made within the 5 030.4 - 5 150.0 MHz sub-band
as necessary to satisfy future air navigation requirements.
APPENDIX TO CHAPTER 4. LIST OF ASSIGNABLE FREQUENCIES
Frequency
(MHz) Annotations
121.5 Emergency frequency
Auxiliary frequency SAR
Reserved for aerodrome surface
communications
[see Table 4-1, Item c)]
Frequency
(MHz) Annotations
GROUP A
Frequencies (MHz)
Reserved for aerodrome surface
communications
[see Table 4-1. Item c)]
GROUP B
Frequencies (MHz)
GROUP C
Frequencies (MHz)
GROUP D
Frequencies (MHz)
Annex I0 - Aeronautical Telecommunications Volume V
GROUP E
Frequencies (MHz)
GROUP F
(see also Table 4-1 (bis))
118.000 - 121.400 in 8.33 kHz steps 121.600 - 123.050 in 8.33 kHz steps 123.150 - 136.475 in 8.33 kHz steps
ATTACHMENT A. CONSIDERATIONS AFFECTING THE DEPLOYMENT OF
VHF COMMUNICATION FREQUENCIES
Introduction
Paragraphs 4.1.5.2 and 4.1.5.3 specify the geographical
separation required for co-channel operation of VHFfacilities
in the aeronautical mobile service. in Figure A-1 the distance
AB indicates the separation required between facilities in
order that aircraft a and b operating at the protection heights
and at the limits of the functional service range of stations A
and B respectively, will not experience harmful interference.
Paragraph 4.1.6.1 recommends the maximum antenna gain
outside the main beam of facilities which provide service
beyond the radio horizon. Figure A-2 illustrates the azimuthal
angle to be protected and the method of derivation. Smaller
beamwidths than 30 degrees are not considered practical at
present.
Note.- The term "main beam" includes all azimuths where
antenna gain exceeds 3 dB above that of a dipole.
Note.- It is necessary to take into account that the efective
radiated powers of transmitting stations may not be equal.
1.2 The desired distance (dD) is the distance between the
desired ground facility and the limit of the functional service
range of that ground facility (see Figure A-3).
Note.- When making assignments using a 14 dB D/U
signal ratio, the potential effects of interference caused by
mute 18s due to high communications loading on co-channel
assignments should be considered.
1.3 The undesired distance (dU) is the distance between
the limit of the functional service ranges of the desired facility
and that of the undesired facility (i.e. the distance between the
aircraft at the edges of the respective service ranges). See
Figure A-1.
1.4 The required geographical separation between the
desired and the undesired facility is therefore dD + dU plus the
service range of the undesired facility (see Figure A-1).
1. Criteria employed in establishing 1.5 If the calculated dU exceeds the RLOS between the
geographical separation between ground aircraft, then a distance as small as the RLOS can be used as
stations for co-channel operation of the distance between the edges of the service volumes.
VHF facilities that have a service
aka up to the radio horizon
1.1 To provide co-channel interference protection of 2. Criteria employed in establishing
14 dB (5 to 1 distance ratio, as shown below) desired signal to adjacent channel frequency deployment
undesired signal (DIU), the free-space loss (FSL) formula is with respect to receiver rejection
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