Selex Sistemi Integrati Inc. DMEL2 部品

1.INSTALLATION, INTEGRATION AND CHECKOUT 
 
1.1 Introduction 
This section contains installation information for the independently   located DME.  If the DME is to be 
collocated with VOR or ILS refer to the basic instructions in this section and to the installation instructions 
for the VOR or ILS equipment.  With respect to general requirements, a good VOR or ILS site will satisfy 
the  DME  requirements  as well.  System performance must be verified by  flight inspection.  

Figure  1-1

 

shows a typical DME site. 
 

 

After flight inspections and prior to use by pilots, it is mandatory that 
the monitor be left in control of the facility and not in bypass . 

 
1.2 Site Information 
 
1.2.1 Site Selection 
The signal radiated from the DME is affected by obstructions and terrain in the immediate vicinity of the 
antenna and by obstructions and terrain within the service range of the station.  An ideal site would be the 
highest ground in the vicinity with level terrain, cleared of all objects for a radius of at least 3000 feet (915 
meters), and with no obstructions extending above the horizontal plane of the antenna within the service 
range of the station.  In most localities, it is not possible to satisfy the ideal site requirements.  Every effort 
must be made to obtain the best site available.  Although no absolute minimum requirements can be stated, 
a site is normally acceptable if it meets the recommendations contained in the following paragraphs. 
 
1.2.1.1 Terrain Features 
The terrain should be level within a radius of 200 feet (61 meters).  In a radius between 200 and 1000 feet 
(61 and 305 meters), a downward slope is acceptable if (1) the rate of descent is not more than 4 feet in 100 
feet (1.22 meters in 30.5 meters) and (2) contour lines are generally circular around the site.  Beyond a 
radius of 1000 feet (305 meters), terrain should be below the horizontal plane of the antenna. 
 
1.2.1.2 Obstructions 
There should be no structures within 750 feet (229 meters) of the antenna. Metallic structures should not 
subtend vertical angles greater than 1.2 degrees as measured from the antenna.  Wooden structures with 
negligible metal content should not subtend vertical angles greater than 2.5 degrees as measured from the 
antenna.  Structures having considerable length (such as aircraft hangers or administration buildings) 
should be situated lengthwise on a radial from the antenna.  Single trees less than 35 feet (11 meters) high 
may be tolerated beyond 750 feet.  No group of trees or groves may be within 1000 feet.  No overhead 
power or control lines are permissible within 750 feet of the antenna.