Publication: Magyar Közlöny
Issue: MK-2009-104 (Year: 2009, Number: 104)
Era: 2004-2010
Section: 
Paragraph Index: 2383

e) radio altitude. Note.— Specific requirements for additional inputs for ACAS II and III are listed in the appropriate sections below. 4.3.9.2 Aircraft antenna system. ACAS shall transmit interrogations and receive replies via two antennas, one mounted on the top of the aircraft and the other on the bottom of the aircraft. The top-mounted antenna shall be directional and capable of being used for direction finding. 4.3.9.2.1 Polarization. Polarization of ACAS transmissions shall be nominally vertical. 4.3.9.2.2 Radiation pattern. The radiation pattern in elevation of each antenna when installed on an aircraft shall be nominally equivalent to that of a quarter-wave monopole on a ground plane. 4.3.9.2.3 ANTENNA SELECTION 4.3.9.2.3.1 Squitter reception. ACAS shall be capable of receiving squitters via the top and bottom antennas. 4.3.9.2.3.2 Interrogations. ACAS interrogations shall not be transmitted simultaneously on both antennas. 4.3.9.3 Pressure-altitude source. The altitude data for own aircraft provided to ACAS shall be obtained from the source that provides the basis for own Mode C or Mode S reports and they shall be provided at the finest quantization available. 4.3.9.3.1 Recommendation.— A source providing a resolution finer than 7.62 m (25 ft) should be used. 4.3.9.3.2 Where a source providing a resolution finer than 7.62 m (25 ft) is not available, and the only altitude data available for own aircraft is Gilham encoded, at least two independent sources shall be used and compared continuously in order to detect encoding errors. 4.3.9.3.3 Recommendation.— Two altitude data sources should be used and compared in order to detect errors before provision to ACAS. 4.3.9.3.4 The provisions of 4.3.10.3 shall apply when the comparison of the two altitude data sources indicates that one of the sources is in error. 4.3.10 Monitoring 4.3.10.1 Monitoring function. ACAS shall continuously perform a monitoring function in order to provide a warning if any of the following conditions at least are satisfied:

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