INTERNATIONAL TELECOMMUNICATION UNION RADIOCOMMUNICATION BUREAU (Direct Fax No. +41 22 730 57 85) Administrative Circular CAR/6 5 April 1994 TO THE ADMINISTRATIONS OF MEMBERS OF THE ITU Proposed approval of one draft new Recommendation and one draft new Question adopted by Radiocommunication Study Group 7 (Science Services) at its meeting from 16-17 March 1994 Draft new Recommendation ITU-R SA.[Doc. 7/125] At the meeting of Radiocommunication Study Group 7 (Science Services), held from 16-17 March 1994, the Study Group unanimously adopted the text of 1 draft new Recommendation and agreed to apply the procedure of Resolution ITU-R 1 (see § 10) for approval of Recommendations between Radiocommunication Assemblies. The title and summary of the Recommendation are given in Annex 1. Having regard to the the provisions of § 10 of Resolution ITU- R 1, I should be grateful if you would inform me by 5 July 1994, whether your Administration approves or does not approve this draft new Recommendation. A Member who indicates that the draft new Recommendation should not be approved is requested to advise the reason and indicate possible changes in order to facilitate further consideration by Radiocommunication Study Group 7 during the study period. After the above-mentioned deadline, the Director of the Radiocommunication Bureau will notify the result of this consultation by Administrative Circular and make arrangements for the Recommendation to be published in accordance with Resolution ITU-R 1. Draft new Question [Doc. 7/143] Radiocommunication Study Group 7 at its meeting held in Geneva from 16-17 March 1994 drafted a new ITU-R Question [Doc. 7/143] to be considered for approval by correspondance according to the provisions of Resolution ITU-R, § 3.3. The Question will be approved if: - "a simple majority of all the Member respondents are in agreement; - and at least 10 replies are received within four months after circulation". The text of this Question is annexed for your approval (see Annex 2). It would be appreciated if you could advise the Director of the Radiocommunication Bureau by 5 August 1994, whether you approve the adoption of this annexed Question for study by the Radiocommunication Study Groups. If the Question is approved it will have the same status as Questions approved at a Radiocommunication Assembly and become the offical text attributed to Study Group 7, and will be published as an Addendum to Book 4 which contains the ITU-R Questions approved by the 1993 Radiocommunication Assembly. Richard C. Kirby Director Annexes: Title and summary of the draft new Recommendation Draft new Question ITU-R [Doc. 7/143] Document attached: Document 7/BL/40 Distribution: - Administrations of Members of the ITU ******* ANNEX 1 Title and summary of the draft new Recommendation adopted by Radiocommunication Study Group 7 (Geneva, 16 to 17 March 1994) Draft new Recommendation ITU-R SA.[Doc. 7/125] 7/BL/40 USE OF THE 13.75 TO 14.0 GHz BAND BY THE SPACE SCIENCE SERVICES** In this Recommendation, space science services srefers to the earth exploration-satellite service and the space research service. AND THE FIXED SATELLITE SERVICE This Recommendation defines acceptable levels of interference for the known altimeters, scatterometers, precipitation radars, and data relay networks that are presently using or plan to use the band 13.75-14 GHz prior to the year 2000 and the criteria needed to protect these missions from unacceptable interference during the period that they have been granted as special status under RR 855B. It verifies that there is a continuing need for the space science services to operate at frequencies in the vicinity of 14 GHz with bandwidths of as much as 500 MHz. It is not necessary that, in the future, the frequencies available for use by the space science services include the 13.75-14 GHz band. This Recommendation recognizes that there is limited compatibility between the primary allocation to the FSS (Earth-to- space) and the secondary allocations to the space research service and the Earth exploration-satellite service in the band 13.75-14 GHz after the year 2000. It is of the opinion that most active sensor operators will choose to redesign their follow-up instruments, beyond those currently in orbit or planned for launch in the near future, to operate below 13.75 GHz, thus avoiding the possibility of interference from the FSS. One long range problem has been identified, however, and that is a necessity to continue operations of an existing relay network well into the 21st century. There is also a need to extend operations of a planned precipitation radar until 1 January 2001 in order to complete its mission. Guidelines for the operation of space science systems that should be taken into account after the appropriate periods of recommended protection is incorporated in this new Recommendation. ******* ANNEX 2 Draft new Question adopted by Radiocommunication Study Group 7 (Geneva, 16 to 17 March 1994) Draft new Question ITU-R [Doc. 7/143] COMPATIBILITY OF ACTIVE SPACEBORNE SENSORS AND SYSTEMS IN THE RADIONAVIGATION AND RADIOLOCATION SERVICES The ITU-R, considering a) that operation of active sensors used on Earth exploration and meteorological satellites is based on the emission and detection of radio signals; b) that these active sensors operate on a secondary basis in bands allocated to the radionavigation and radiolocation services on a primary basis; c) that the safety aspects of the radionavigation service are recognized in RR953; d) that the compatibility of active spaceborne sensors and systems operating in the radiodetermination services is a desirable objective; e) that the radiolocation service provides essential functions, decides that the following Question should be studied 1 What are the technical characteristics and performance criteria for active spaceborne sensors in bands of considering b)? 2 What are the interference criteria for active spaceborne sensors in decides 1? 3 What are the technical characteristics and performance criteria for radionavigation and radiolocation systems in the bands of considering b)? 4 What are the interference criteria for radionavigation and radiolocation systems in decides 3? 5 Can active spaceborne sensors operate compatibly with the radionavigation and radiolocation systems in common bands without constraints on the parameters of either the sensors or the radiodetermination systems? _____________