Liaison statement from SE28 to ETSI/TC-SES

Liaison statement from SE28 to ETSI/TC-SES

The European Science Foundation is an association of its 67 member research councils and academies in 23 countries. The ESF brings European scientists together to work on topics of common concern, to co-ordinate the use of expensive facilities, and to discover and define new endeavors that will benefit from a co-operative approach
The scientific work sponsored by ESF includes basic research in the natural sciences, the medical and biosciences, the humanities and the social sciences.
The ESF links scholarship and research supported by its members and adds value by cooperation across national frontiers. Through its function as coordinator, and also by holding workshops and conferences and by enabling researchers to visit and study in laboratories throughout Europe, the ESF works for the advancement of European science.

On behalf of European radio astronomers, the ESF Committee on Radio Astronomy Frequencies, CRAF, coordinates activities to keep the frequency bands used by radio astronomers free from interference.

  • Subject: Revision of limits to AES in DEN/SES-00023 V1.1.5

    Paris, 27-28 January 2000

    Subject: This liaison statement is in response to the liaison letter ETSI/TC-SES sent to CEPT SE PT28 (June 24, 1999).

  • - protection of radio astronomy in the band 1660-1670 MHz:

    SE28 discussed the protection of the Radio Astronomy Service in the band 1660-1670 MHz from harmful interference from AESs operating the band 1626.5-1660.5 MHz. An analysis was carried out by Inmarsat and accepted by CRAF. This statistical approach is based on the density of aircraft within a certain simulation area considered to be sufficiently large to encompass all potential interfering aircraft, the number of aircraft equipped with Satcom, the utilisation rate of AESs, and the probability of 2 simultaneous calls from the same terminal. This approach shows that with a reduction of the unwanted emission level, the radio astronomy protection criteria will be met.

    SE28 therefore recommends to change the power output levels stated in the DEN/SES-00023 v.1.1.5, Section 9, table 13 as follows:

    Frequency band1660-1670 MHz
    Narrow band spurious-49.5 dBWfor a reference bandwidth of 20 kHz
    Wide band spurious-39.5 dBWfor a reference bandwidth of 1 MHz

    These new levels being applicable to Harmonics, Spurious and Noisy density levels produced by an AES operating in the 1626.5-1660.5 MHz band.

    It has been pointed out that such complete statistical analysis had not been performed for the assessment of the unwanted emission level from AES falling into the band 1610.6-1613.8 MHz and that, consequently, the value of -80 dBW/MHz which had been previously proposed to TC SES for this band might be unduly constraining. In absence of planned further SE28 meeting, the two parties which were involved in this earlier study, CRAF and Iridium, have been invited to carry out a full statistical analysis and to agree on some proposal to be submitted directly to the resolution meeting on DEN/SES-00023.

  • - Compatibility MSS operations in the band 1614-1626.5 MHz and HSN and IM density levels from AES transmitting in the band 1626.5-1660.5 MHz

    The drafting group distinguished the following aspects:
    i. Uplink MSS in the band 1614-1626.5 MHz versus uplink MES in the band 1626.5-1660.5 MHz:
    SE28 noted that the issue was not discussed by WP8D as indicated in footnote 1 to document ITU-R 8/128-E. SE28 considers that, as far as possible, the AES unwanted emission power below 1626.5 MHz should be made close to the one agreed in SG8 for non AES terminals. The AES density, which is expected to be lower than the density of handset stations, will guarantee that their interference will not significantly add up on the aggregate interference level from land mobile earth stations.
    ii. Two AESs on the same aircraft:
    SE28 considers that this is an issue for ICAO.

    Last modified: July 1, 2000