Committee on Radio Astronomy Frequencies

What telescope parameters should be used for coordination work and compatibility studies?

What telescope parameters should be used for coordination work and compatibility studies?

Answer:

For transparency and clarity, CRAF refers to agreed ITU-R and CEPT documentation. In addition some additional assumptions are made to enable proper completion of the studies:

  • Protection criteria: Recommendation ITU-R RA.769 gives the protection criteria for the Radio Astronomy Service. It was developed for the purpose of inter alia coordination.

  • Telescope parameters:
    - Receiver sensitivity: The receiver sensitivity for a radio telescope is given in Recommendation ITU-R RA.769. From the system parameters given in this document, the threshold levels for the protection of radio astronomy are derived and tabulated.
    - Antenna pattern: The antenna pattern used in Recommendation ITU-R RA.769 is taken from Recommendation ITU-R SA.509. The protection criteria in Recommendation ITU-R RA.769 are given for >19º from boresight. For the use of the epfd concept information about the whole antenna pattern is required. The model which describes also the inner part of the antenna pattern and what is currently discussed in ITU-R WP7D is given in one of the meeting documents of the last 7D meeting (see chairman's report of that meeting for further details).
    - Antenna diameter: For the application of the epfd concept, CRAF recently suggested to use a typical value for the diameter of a radio telescope of 75 meters. The results do not appear to be very sensitive on this number.
    - Minimum elevation: ITU-R WP7D discussed recently that a minimum elevation of 5o should be used in coordination studies. This number is not accepted yet by all Administrations because of the different geographical situations in different countries.
    - Height of antenna from ground: For a 75 meter antenna a value of about 50 meter should be used.

    Use of a specific frequency band by a radio astronomy station: For most stations applies that observations are done in single dish mode, interferometer mode or as an element of a Very Long Baseline Interferometry, VLBI, network. CRAF does not understand why more detailed knowledge about the use of a specific frequency band is relevant for a coordination study: It is important that a European radio astronomy station using this frequency is protected for operations in single dish mode.

    Last modified: January 18, 2002