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The dipole antenna of a radar altimeter of 1947. A radar altimeter (RA), also called a radio altimeter (RALT), electronic altimeter, reflection altimeter, or low-range radio altimeter (LRRA), measures altitude above the terrain presently beneath an aircraft or spacecraft by timing how long it takes a beam of radio waves to travel to ground, reflect, and return to the craft.
Tactical information display (TID) of radar data in the rear seat of an F-14A. The radar antenna of an AN/AWG-9 on display in the USS Hornet Museum. The AN/AWG-9 and AN/APG-71 radars are all-weather, multi-mode X band pulse-Doppler radar systems used in the F-14 Tomcat, and also tested on TA-3B. [1]
The radar measures the distance to the reflector by measuring the time of the round trip from emission of a pulse to reception, dividing this by two, and then multiplying by the speed of light. To be accepted, the received pulse has to lie within a period of time called the range gate .
Radar designers try to use the highest PRF possible commensurate with the other factors that constrain it, as described below. There are two other facets related to PRF that the designer must weigh very carefully; the beamwidth characteristics of the antenna, and the required periodicity with which the radar must sweep the field of view.
In addition, an antenna or an array can be time-shared between transmitter and receiver of the T/R module, whereas FMCW radars require two antennas or arrays, one for transmit and one for receive. A drawback of half-duplex operation is the existence of a blind zone in the immediate vicinity of the radar sensor.
It is a relocatable, solid-state, all-weather radar with dual-channel, frequency diversity, remote operator controls, and a dual beam tower mounted antenna. The radar provides controllers with range azimuth of aircraft within a 60 nautical mile radius. ASR 8 used a klystron as transmitters power amplifier stage with a load of 79 kV and 40A.
AN/APQ-157 AN/APQ-153 radar with dual line-replaceable units (with the exception of the radar antenna) for the twin seater versions of Northrop F-5; AN/APQ-158 for the MH-53 Pave Low helicopter; AN/APQ-159 improved AN/APQ-153 fire control radar by Emerson Electric Company for Northrop F-5; AN/APQ-160 attack radar for EF-111A Raven
The AN/APG-68(V)9 [6] radar system consists of the following line-replaceable units: Antenna; Medium Duty Transmitter (MDT) Modular Receiver/Exciter (MoRE) Common Radar Processor (CoRP) The AN/APG-68(V)9 radar is the latest development. Besides the increase in scan range compared to the previous version, it has a Synthetic aperture radar (SAR ...