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Cartes-fiches
Weather radar: Wetter Radar hast to be
has to be stabilized in the horizontal plane to eliminate the influence of pitch and roll movements on its direction ==> the images shown on the display refer to the horizontal plane and not the aircrafts longitudinal axis
Weather radar: 2 differents patterns are applied by weather radars
1. Pencil shaped (cone-shaped) 2. Cosecant squared shaped => fan-shaped
Weather radar: cosecant squared shaped ==> Fan shapped
50-60 N for mapping
Weather radar: pencil shaped
a typical beam width => long range ground mapping => 50-60 NM => more power can be concentrated in the narrower beam
Weather radar: Two different antenna technologies for radar applications
1. Parabolic reflector: the antenna focus the radio waves, slot antennae superposes (überlagern) them
2. Slot antenna: consists of many small antennas, which all transmit teh same signal at different phase correlations ==> produces less side lobes
Weather radar: on teh ground ?
high power radiation from the system max cause harm to people around the aircraft. Some but not all systems types are coupled to the air-ground switch (prevents transmission as long as the aircraft is on the ground) = caution when used n ground
Weather radar: Tilt management Aufpassen auf was?
1. curvature of the earth 2. determine the cop of a cloud
Weather radar: Tilt management ==> distance of 80 NM and 160 NM => horizontal alitude
80 NM = 6000 ft ==> 160 NM = 22'000 ft
Weather radar: When is the liquid water content at is max?
Just below freezing level the liquid water content is at its maximum => big radar echo
Weather radar: Alarming patterns by the radar picture ?
shapes like fingers, U-shaped scallop shaped
Weather radar: How you can find out about targets behind strong reflecting areas?
turn the antenna down => if the black area disappears and is replaced by ground = conductors of the precipitation cell are rendered nearly correctly . if the black are remains = may safely assume the presence of radar shadow by a intense echo
Weather radar: danger of Misinterpretation - Angular (azimutal) Resolution
The diameter of the radar beam increases with distances with distance from the target and thus the resolution suffers
Weather radar: danger of Misinterpretation - Blind Alley
focus on short range observation, a dangerous so-calles Blind Alley situation may arise
Weather radar: Avoid Hazardous Weather
by the windward side has to be passed at a minimum distance of about 20 NM
Weather radar: danger of Misinterpretation - Oversacnning
the radar beam ist adjusted to high
Weather radar: Ground mapping
the map mode has to be activated => After adjusting the intended range the tilt is turned downwards until the desired amount of terrain is displayed ==> Relative bearing and the range towards prominent land features
Weather radar: What is the prupose of the gain control function encountered in weather radar systems?
It controls the sensitivity level of the receiver
SSR: Disadvantage
Secondary Surveillance Radar: need for a functioning on-board transponder
SSR: transmits on a fixed frequency
1030 MHz => on board transponder replies with a pulse coded (pulse train) at a fixed frequency of 1090
SSR: TCAS
Traffic Collision Avoidance Systems => possible to trigger the same response with other interrogators working on the same frequency
SSR: Has two different type of information
1. Identification (the squawk) => Mode A 2. Barometric altitude based on 1013.25 hPa => mode C
SSR: the interrogat applies a specifiec pulse sequence => consists?
each sequence consists of three pulses (p1 P2 and P3) and the time space between P1 and P3 indicates whatever the secondary radar system inquires about squawk or the aircrafts pressure ==> Sends out 2 pulses P1 and P3
SSR: The aircrafts response on a specific pulse sequence ?
the frame pulse F1 followed by 23 informations pulses and ends with F2
SSR: Mode A wie viele verschiedene codes
carry the coded identification the squawk => 8`4 => 4096 different codes are selected
SSR: Mode C, ft Schritte and where iit starts
the code barometric altitude => 1013.25 HPa ==>100 ft Schritte => 1200 ft to 126700 ft
SSR: SPI
Special Position identification => IDENT => transmitted after the last frame pulse F2 => 20 seconds while the IDENT button is pressed
SSR: SLS
Side Lobe Suppression => SSR energy not only in the direction of the main lobe but also towards other directions (see Lobe) => two transmitting =>
1. one directional antenna (main beam)
2. more or less omni-directional antenna that produces a circular control pattern
=> main beam sends out the two interrogation pulses Pa and P3 while teh side loob suppresions pulse is transmitted via non-directional control pattern
=> if P2 pulse is euqal or above the amplitude of P1 => teh aircraft is within a side lobe and the transpnder does not respond
SSR: ALT by transponder control panel => ?
system replies to SSR A/C/S
1200
CFR in teh USA
2000
Provides identification to an aircraft that has not received instructions from ATC to operate the transponder
SSR: Transpondercode wechseln => welcher Modus wählen
SBY
SSR: Beim Mode A and C, was kann man alles auf de Radar des ATC sehen
Flight number, GS, FL (changes automatically between FL and altitude) vertical speed, type, Wake turbulence and destination
SSR: Limitations A/C mode Shielding
Abschwirren => transponder system is shielded if the aircraft is banked => the interrogation may also be detected, but the reply does not reach the ground station du shielding
SSR: Limitations A/C mode Garblinh
replies overlap from two aircraft => corresponds approximately 1.7 NM = Target to close to each other
1. Non-synchronous garbling: two replies overlap in time and tehir time grids are not congurent => the signals can be separated
2. Synchronous garbling: two or more replies overlap in time and their time grids are congurrent
SSR: Limitations A/C mode FRUIT
False replies Unsynchronized In Time => False replies unsynchronized to interrogator (Fragesteller) transmission => ground station receive replies elicited by other interrogators from other aircraft => reply several in time
SSR: Mode S
to overcome the limitations of the older A/C system => was designed as a selective system = each aircraft has a once defined address
SSR: Mode S code
consist in a 24-bit code which allows for more than 16'000'000 = 2`24 individual codes => ground station can contact each aircraft independently and establish an individual data link ===> preventing multiple replies and reducing radio traffic load
SSR: Roll call (Mode S)
are selective calls addressed to one individual aircraft
SSR: All-call (S-Mode)
expect response from all aircraft
SSR: S mode two stages
1. Elementary surveillance ELS-DAP's: aircraft position, identity, reporting 25 ft, flight sttaus
2. Enhanced surveillance EH's DAPS's: Magnetic Heading, TT, True Angel rate, IAS, Mach, GS, Vertical rate, Roll Angle, Selected Altitude,
