Radio Nav Flashcards
c =
c = 3 x 108 m/s = ~162 000 nm/s
Radio Range
Max theoretical range (nm) = 1.23 √H1 + 1.23 √H2 (ft)
Range over land ~ 2 √Power (W)
Range over water ~ 3 √Power (W)
VLMHVUSE
VHF 118 MHz to 136.975 MHz
VHF 118 MHz to 136.975 MHz
Max theoretical range:
Min range:
Max theoretical range = c/2 x PRF
PRF = 1/PRP
Min range = (c x pulse length)/2
QTE
QUJ
QDR
QDM
Accuracy:
Class A
Class B
Class C
Class D
QTE True bearing from the station (True Emission)
QUJ True bearing to the station (Union Jack - lines converge!)
QDR Mag bearing from the station (Direct Radial)
QDM Mag bearing to the station
Accuracy:
Class A +/-2º
Class B +/-5º (most common)
Class C +/-10º
Class D >10º
NDB and ADF
Freqs/type of wave:
In Europe:
Range:
Greatest errors:
NDB and ADF (Automatic Direction Finder)
190 KHz to 1750 KHz (surface waves)
In Europe, usually 200 KHz to 455 kHz
Straddle MF and LF - hectometric/kilometric aid
Range over land ~ 2 √Power (W)
Range over water ~ 3 √Power (W)
Greatest errors: TS
Freq/type of wave
2 pulses, separated by…
To avoid returns from other aircraft…
To remove ground returns…
Echo Protection Circuit (EPC)
UHF: 960 MHz to 1215 MHz /Propogation is direct wave or space wave
Aircraft interrogator transmits 2 pulses, separated by 12μs - ground transponder re-transmits them after 50 μs delay. Need to remember this to calculate distance.
To avoid returns from other aircraft, the PRF is jittered makes each pulse train unique to each aircraft.
To remove ground returns, transponder retransmits a different frequency, 63 MHz apart from the interrogator - but at the same (jittered) PRF.
The received signal is checked by the aircraft Echo Protection Circuit (EPC) to ensure that the rx PRF is the same as the tx signal, to eliminate the possibility that it is a reply to another aircraft.
Localiser:
Glidepath:
Markers:
Ident:
Localiser: VHF 108 MHz to 111.95 MHz (Amplitude Modulation)
Shared with Terminal VOR so ILS uses: odd 100 KHz freq
(ILS > 1LS = odd) and odd+50 KHz
Glidepath: 40 x spot UHF freqs (329.3 MHz to 335 MHz) paired with VHF
Markers: 75 MHz
Ident: 1020 Hz tone on localiser carrier wave.
ILS Displays
Localiser: one dot is…
Glideslope: one dot is…
Max. safe fly-up indication:
ILS Displays
Localiser: one dot is 0.5º/FSD is 2.5º
Glideslope: one dot is 0.14º/FSD is 0.7º
Half FSD is the max. safe fly-up indication
Localiser: LEFT/RIGHT
Glidepath: LOWER/UPPER
90 Hz lobes are LEFT and UPPER
150 Hz lobes and RIGHT and LOWER
LARD: Left Above (90), Right Down (150)
Localiser
Glideslope
Lower lobe starts at…
Upper limit is at…
Glidepath beams extend to…
…for a steep glidepath.
Sidelobes
Localiser
17nm/35º
25nm/10º
Glieslope
Lower lobe starts at 0.45 x GP angle: 1.35º for a 3º GP
Upper limit is at 1.75 x GP angle: 5.25º for a 3º GP
> 3º GP angle is a steep glidepath
Glidepath beams extend to 10 nm, +/- 8º either side of centreline
Out to 8 nm for a steep glidepath.
Sidelobes can create false glide slopes above the real glidepath.
Therefore, must never attack the glideslope from above.
First false glideslope at 2 x GP angle.
OM
MM
IM
Microwave Landing System (MLS)
Channels
Band
Spacing
Microwave Landing System (MLS)
MLS uses 200 channels in the SHF band (5031 MHz to 5090 MHz) = 300 KHz spacing
MLS Coverage
Azimuth
Elevation
DME/P
MLS Coverage
Azimuth cover is +/- 40º and out to 20 nm.
Elevation limits are 0.9º up to 20º and out to 20 000 ft and 20 nm.
DME/P goes out to 22 nm.
