test 2: comms and radar Flashcards
MCS’s EHSI displays a combination of…
TACAN and FMS data.
Primary function of FMS?
In-flight management of the flight plan.
Functions of FMS are…
Getting a/c position,
providing a flight plan route,
ETE and fuel management calculations, and
autopilot along flight plan route
FMS provides… to allow for INS drift correction.
FMS, GPS, and INS positions during flight
GPS Strengths
high accuracy,
continuous updates, and
three dimensional.
GPS Weaknesses
subject to satellite, weather, and interference problems
The Two accuracies of GPS are…
SPS (less accurate),
PPS (more accurate).
CNAF M-3710.7 only allows SPS for…
navigation in civil controlled airspace in support of IFR operations.
Satellite Clock Error
Satellite clock does not match master GPS time.
Ephimeris Error
Satellite is not exactly where it was thought to be.
Multipath
signal arrives from two different paths usually due to reflections.
How do GPS and INS support eachother?
GPS updates INS,
INS is not jammable
When might GPS not be available?
Mountain shadowing satellites, jamming, or high dynamic maneuvers
INS Weaknesses
INS doesn’t give Alt info,
no outside verification (may drift)
INS strengths
self-contained,
cannot be jammed or interfered,
immune to weather, antenna, and signal problems
Heart of INS
accelerometers
Accelerometer gives no output…
when stationary or at a constant velocity
INS Updates
At least once per hour, if they differ by more than 1 mile INS should be updated to GPS location.
VHF Band
108 - 136.975 MHz
Guard: 121.5 MHz
Secure vs Non-secure Voice Colors
Plain voice (red),
Secure Voice (green)
UHF Band
225.0 - 399.975 MHz
Guard: 243.00 MHz
HF Band
3 - 30 MHz
HF Radio Weakness
25x power of VHF or UHF and susceptible to overheating
SATCOM
no range limits, communicate anywhere in the world, transmissions are made and received on UHF freqs
