3.4 Satellite-based data collection and dissemination systems
3.4.1 Introduction
3.4.1.1 Satellite-based data collection and distribution systems are integrated in the GTS as an essential element of the global, regional and national levels of the GTS.
3.4.1.2 They should comply with the organization and principles of the GTS, particularly with respect to the functions and responsibilities of meteorological telecommunication centres.
3.4.1.3 They operate through communication functions of meteorological satellites and through public telecommunication services via satellite.
3.4.1.4 The principles for the planning of satellite-based data distribution should be as follows:

(a) A satellite-based distribution system should be a telecommunication technique complementing the point-to-point GTS circuits;
(b) RSMCs, RTHs and NMCs should have the capacity to insert meteorological information (either directly or indirectly) into the regional/multi-regional satellite-based distribution system.

3.4.2 Data collection systems via meteorological satellite
3.4.2.1 Data collection systems and associated data retransmission systems, when available, operated via geostationary or near-polar orbiting meteorological satellites constitute an integral part of the GTS for the collection of observations. Basic meteorological data collected in this way normally requires validation by the NMC before it is disseminated on the GTS for general use. By agreement, data not subject to verification may be inserted onto the GTS via a nominated NMC.
3.4.2.2 Data collection platforms (DCPs) shall be maintained by the DCP operators. Quality control of the output from these platforms is the responsibility of the operator and the nominated NMC.
3.4.2.3 Unless agreed upon otherwise, the meteorological satellite operator shall ensure the prompt transmission of the received DCP message to the NMC responsible for quality control and verification prior to its general dissemination on the GTS.
3.4.2.4 The data collection platforms must operate in accordance with the parameters as defined by the meteorological satellite operator.

3.4.3 Data distribution systems via meteorological satellites
3.4.3.1 Data distribution systems operated via geostationary meteorological satellites constitute an integral part of the GTS for the point-to-multipoint transmission of observational data and processed information in character, binary, graphical and pictorial form, within the agreed WWW system.
3.4.3.2 The point-to-multipoint service to be provided by the meteorological satellite operator shall be subject to agreement between the NMCs concerned and the agencies participating in the programmes. The NMC acting as data provider to the meteorological satellite operator whether they originate the data or not shall be responsible for relaying the input data.
3.4.3.3 The contents and schedules of transmission, as well as frequencies, orbital data and area coverage of meteorological satellites shall be provided by satellite operators.

Notes:
(1) The contents and schedules of transmission by meteorological satellites are published in WMO Publication No. 9, Volume C.
(2) Information on meteorological satellite programmes operated by Members and organizations is
published in WMO Publication No. 411.

3.4.4 Point-to-multipoint and multipoint-to-point transmission via telecommunication satellites
3.4.4.1 Point-to-multipoint telecommunication service via satellite provided by telecommunication administrations/ agencies may be used as an integral part of the GTS for the direct distribution to NMCs of observational data and processed information from WMCs, RSMCs and NMCs at the global, multi-regional or regional level.
3.4.4.2 Multipoint-to-point telecommunications service via satellite provided by telecommunication administrations/agencies may be used as an integral part of the GTS for the implementation of regional meteorological telecommunications networks, in accordance with the plans established by the regional associations.

3.5 HF-radio broadcasts of meteorological information
3.5.1 General
Until the integrated network, as defined in principle 2 (see paragraph 1.3 above), is completed, HF-radio-broadcasts may be used in order to meet the requirements of the WWW for the dissemination of meteorological information.

3.5.2 Responsibilities of Members
3.5.2.1 When a Member establishes within its territory a routine meteorological broadcast intended for use by other Members, the Member shall send the following information, as appropriate, to the Secretariat:

(a) Name and call sign, or other identification, of transmitting station;
(b) Power supplied to the antenna;
(c) Class of emission, necessary band width;
(d) Frequencies;
(e) Contents, detailed time schedules and WMO category of the broadcast;
(f) Index of cooperation and drum speed(s) of facsimile transmitter;
(g) Specific point(s) or area(s) in which the broadcast is intended to be received.

3.5.2.2 Amendments to the information supplied under paragraph 3.5.2.1 above shall be sent to the Secretariat at least two months before a routine meteorological broadcast is established or a change is made in an existing routine broadcast.
3.5.2.3 In addition to the information supplied to the Secretariat under paragraph 3.5.2.2 above, notification of impending changes in frequencies or in time schedules of any routine meteorological radio broadcasts shall be included by the Member concerned in the broadcasts for main synoptic hours for at least three days immediately prior to the change.
3.5.2.4 When it is necessary to discontinue a broadcast intended primarily for reception by other Members, provision shall be made to continue to meet the requirements of all recipients of the broadcast.

Note: Broadcasts by a Member intended primarily for its own use are not affected by the above, even if they are used by other Members.

3.5.2.5 When it is necessary or desirable to change the mode of a broadcast intended primarily for reception by other Members, notice of a duration agreed regionally or multilaterally shall be given to the recipients.

Notes:
(1) On expiry of this notice it will be assumed that the requirements of the recipients are met by the broadcasts in the new mode.
(2) Broadcasts by a Member intended primarily for its own use are not affected by the above, even if they are used by other Members.

3.5.2.6 A Member experiencing difficulties in receiving or observing any deficiencies in a broadcast intended for its reception, as agreed, should first take corrective action of a local nature and, if unsuccessful, notify in detail the Member making this broadcast and also keep the president of the relevant regional association informed as necessary.

3.5.3 The system of radio broadcasts shall be as follows:
3.5.3.1 RTT broadcasts

3.5.3.2 Radio-facsimile broadcast

* This classification does not preclude the establishment of facsimile broadcasts by NMCs