Radio Altimeter Flashcards
Residual height
The height diff between the landing gear and the receiver ,(also copesnate for the resudal cable lenthh
Principle of operation
~the rad alt uses continuos wave transmissions
Requires separateantenna for transmission and reception
Carrier wave at 4300Mhz
This is in the SHF band
Wavelength is 7.1cm
~frequency modulated 50 Mhz abve and below the carrier wave
- a total bandwidth of 100 Mhz
The antennae produce a concial beam
Compares the transmitted an dreflected signals
~return aignal is at a different point in the modulation sequence
~produces a frequency difference
~the greater the height the greater the frequency differecne
~frequency difference is proportional to height above the surfgace
The signal refelcted fro a distant surface is very weak than a nearby surface
Accuaracy below 500 ft is =/-2 feet
Or
=/- 1,5% which ever is greater
