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CHAPTER 10. POINT-TO-MULTIPOINT
COMMUNICATIONS
10.1 SERVICE VIA SATELLITE
FOR THE DISSEMINATION OF
AERONAUTICAL INFORMATION
10.1.1 Point-to-multipoint telecommunication service
via satellite to support the dissemination of aeronautical
information shall be based on full-time, non pre-emptible,
protected services as defined in the relevant CCITT
Recommendations.
10.2 SERVICE VIA SATELLITE
FOR THE DISSEMINATION
OF WAFS PRODUCTS
10.2.1 Recornrnendation.- System characteristics
should include the following:
a) frequency - C-band, earth-to-satellite, 6 GHz band,
satellite-to-earth, 4 GHz band;
b) capacity with effective signalling rate of not less
than 9 600 bits/s;
C) bit error rates - better than 1 in 10';
d) forward error correction; and
e) availability 99.95 per cent.
ANNEX 10 - VOLUME 111
7/11/96
No. 71
THIS PACE INTENTIONALLY LEFT BLANK
INTERNATIONAL STANDARDS AND
RECOMMENDED PRACTICES
CHAPTER 1. DEFINITIONS
Note.- Material on secondary power supply and guidance material concerning reliability and availability for communication
systems is contained in Annex 10, Volume 1, 2.9 and Volume I. Attachment E respectively.
ANNEX 10 - VOLUME 111
7/11/94
No. 71
CHAPTER 2. AERONAUTICAL MOBILE SERVICE
2.1 AIR-GROUND VHF COMMUNICATION
SYSTEM CHARACTERISTICS
Note.- In the fol[owi~zg text the channel spaczng for 8.33 kHz
channel assignments is dejned as 25 kHz divided by 3 which
is 5.3333 ... kHz.
2.1.1 The characteristics of the air-ground VHF communicalion
system used in the International Aeronautical
Mobile Service shall be in conformity with the following
specifications:
2.1.1.1 Radiotelephone emissions shall be double
sideband (DSB) amplitude modulated (AM) carriers. The
designation of emission is A3E, as specified in the ITU Radio
Regulations.
2.1.1.2 Spurious emissions shall be kept at the lowest
valuc which the state of technique and the 'nature of the
service permit.
Note.- Appendix 8 to the Radio Regulations contains the
tolerances for the levels of spurious emissions to which
transmitters must conform in accordance with RR- 304.
2.1.1.3 The radio frequencies used shall be selected from
the radio frequencies in the band 117.975 - 136 MHz and the
band 136 - 137 MHz subject to the conditions of Radio
Regulation 595. The separation between assignable frequencies
(channel spacing) and frequency tolerances applicable to
elements of the system shall be as specified in Volume V.
Note.-- The band 117.975 - I32 MHz was allocated to
the Aeronautical Mobile (R) Service in rhe Radio Regulations
(1947). By subsequent revisions to the Regulations at ITU
World Administrative Conferences the bands 132 - 136 MHz
and 136 - 137 MHz were added to the (R) allocation under
conditions which difSer .for ITU Regions, or for specified
countries or combinations of countries.
cent from the assigned frequency. Where 25 kHz channel
spacing is introduced in accordance with Volume V, the radio
frequency of operation shall not vary more than plus or minus
0.002 per cent from the assigned frequency. Where 8.33 kHz
channel spacing is introd~lced in accordance with Volume V,
the radio frequency of operation shall not vary more than plus
or minus 0.0001 per cent from the assigned frequency.
Note.- The above tolerances will not be suitable for offset
carrier systems.
2.2.1 -1 .I Offset carrier systems in 25 kHz, 50 kHz and
100 kHz channel spaced environments. The stability of individual
carriers of an offset carrier system shall be snch as to
prevent first-order heterodyne frequencies of less than 4 kHz
and, additionally, the maximum frequency excursion of the
outer carrier frequencies from the assigned carrier frequency
shall not exceed 8 kHz. Offset carrier systems shall not be
used on 8.33 kHz spaced channels.
Note.- Examples of the required stability of the individual
carriers of offset carrier systems may be found at Attachment
A to Part II.
Recommendation.- On a high percentage of occasions,
the effective radiated power should be such as to provide a
$field strength of a least 75 microvolts per metre (minus
109 &w/m2) within the defined operational coverage of the
jacility, on the basis of free space propagation.
2.2.1.3 Modulation. A peak modulation factor of at least
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