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At what Frequency operate DME
Distance measuring equipment (DME) is a transponder-based radio navigation technology that measures slant range distance by timing the propagation delay of VHF or UHF radio signals. DME frequencies are paired to VHF omnidirectional range (VOR) frequencies and a DME interrogator is designed to automatically tune to the corresponding DME frequency when the associated VOR frequency is selected. An airplane’s DME interrogator uses frequencies from 1025 to 1150 MHz. DME transponders transmit on a channel in the 962 to 1213 MHz range and receive on a corresponding channel between 1025 to 1150 MHz.
Билет №41
Give the four Radar Definitions.
1) Pulse length alternatively known as pulse width is the duration of the pulse in microseconds.
2) Pulse repetition frequency is the number of pulse transmitted per second. Otherwise known as the pulse recurrence frequency.
3) Pulse repetition interval is the time interval from the start of one pulse to the start of the next. The pulse repetition (or recurrence) interval is the reciprocal of the pulse repetition frequency. PRI=1/PRF
4) Beam width describes the angular dimension of the radiation pattern. Most radars make use of aerials that concentrate the energy into a narrow beam.
Describe the term Primary Radar.
Primary radar relies on reflected energy, that is echoes of its own transmissions.
Examples:
· Airborne Weather Radar (AWR)
· Radar Altimeter
· Precision Approach Radar (PAR)
· Primary Surveillance Radar
Advantage of Primary Radar: it is self-contained and does not require the cooperation of the target.
At what Frequency operate NDB.
The source of the radio waves used by ADF is normally a non-directional beacon (NDB) transmitting in all directions, as its name implies. Frequency surface wave range increases as frequency decreases because attenuation is reduced. Frequency bands – LF and MF. Frequencies – 190 kHz to 1750 kHz (most commonly 200-500kHz).
Билет №42
1). INTERROGATOR. The ground-based transmitter which is known as the INTERROGATOR transmits on 1030MHz. The interrogator pulses from the ground can be radiated from a directional SSR aerial mounted on the primary radar aerial. The transponder is interrogated every time the radar scans the aircraft
2). Typical SSR Operation:
1.The pilot selects an identification code.
2.The SSR ground transmitter sends a coded interrogation signal on 1030MHz as the primary radar system detect the aircraft. This coded signal is in the form of pairs of pulses and the spacing of the pulses in each pair determines the MODE of the interrogation.
3.The interrogation signal is received, detected and decoded by the airborne transponder.
4.The airborne transponder encodes and transmits a set of reply signals, depending upon mode and code selected.
5.The reply signal is then received, decoded and displayed at the ATC unit.
3). At what Frequency operate ILS.ILS is a runway approach aid providing lateral(localizer) and vertical(glideslope) guidance that allows aircraft to safely approach the runway from several miles out. Localizer transmit in the VHF band on frequencies between 108 and 112MHz. Glide Slope transmissions are in the UHF band on frequencies between 329 and 335MHz.