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2 Definition
Technical Safeguarding is the process employed to protect radio signals from being affected by physical or electromagnetic changes in their transmission environment.
3 Background
Technical Safeguarding consists of two processes, Physical Protection and Radio Spectrum Protection.
4 Physical Protection
4.1 Most physical objects act as reflectors or diffractors of radio signals. A combination of object size, material, proximity and incident radio wavelength, can make them particularly efficient reflectors or diffractors. Technical site safeguarding, a process applied as part of the technical safeguarding of Radio Sites, seeks to prevent any development near to a radio transmitter or receiver site, which may degrade the radio signal by enabling such reflection or diffraction.
4.2 Physical Protection Process
4.2.1 Every aeronautical radio station requires a technical area to be safeguarded against the possibility that buildings or other structures erected within the safeguarded area cause interference to the signal radiated by that station.
On an aeronautical chart, a frame, representing this area, is drawn around the aerial of the radio aid. If a proposed development falls within that frame or volume, further analysis, or reasoned outright rejection should be considered. In the case of development within an ILS area it is expected that computer modelling of the development is undertaken. The size and shape of the frame or volume is dependent upon the type of equipment and its aerial system.
4.2.2 The dimensions provided below are examples of frame sizes associated with specific types of equipment. These sizes should be applied in the absence of data from other sources. Aerodromes are encouraged to obtain specific criteria from the manufacturer or supplier of their equipment. It is likely that the manufacturer may specify a smaller area to be safeguarded, which could provide operational benefits to the Aerodrome. Aerodromes are expected to maintain and apply criteria pertinent to their own technical sites. The Engineering Inspector may wish to examine the criteria used.
4.3 Example frame sizes:
4.3.1 ILS
NOTE: The following dimensions should not be confused with the ILS Critical and Sensitive areas.
4.3.1.1 ILS Localiser Cat I/II The frame can be defined as two separate sectors: a) A sector of 750 metres radius centred on the localiser and .60. about the runway
centreline at ground level, in the direction of the runway threshold. b) A sector, centred on the localiser, .15. about the runway centreline and 1500 metres along the runway, at ground level, in the direction of the runway threshold.
4.3.1.2 ILS Localiser Cat III
The above Cat I/II sectors plus two additional sectors:
a) A rectangle 300 metres either side of and parallel to the extended runway centreline commencing 100 metres behind the respective localiser and extending to 100 metres beyond the end of concrete at the landing end of the respective runway. This area is defined at ground level.
b) A volume commencing 100 metres from the end of concrete at ground level on a projected 1:50 slope to a range of 1000 metres and .300 metres about the extended runway centreline.
NOTE 1:These frames are defined with respect to the localiser site and the landing 'end of concrete' to take account of the variable length of runways and inset threshold conditions.
NOTE 2:Aerodromes may consider extending the above Cat III criteria of . 300 metres to . 500 metres if large scale development on the edge of the . 300 metre boundary is likely.
4.3.2 ILS Glide Path This sector is defined with respect to the glide path aerial mast. A sector of 750 metres radius .60. about a line originating at the base of the glide
path aerial parallel to the approach runway centreline.
4.3.3 DME associated with ILS or MLS
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本文链接地址：CAP 670 Air Traffic Services Safety Requirements 1(94)
