MC-130 Mission Systems Flashcards
Capabilities and limitations of ring laser gyro system
Capes:
- Independent from external sources
- Cannot be jammed
- Provides heading, acceleration, attitude, velocity, position
- Provides kalman filter w/X, Y, Z velocities, pitch and roll, true heading
Lims
- Drifts
- Requires alignment
- Air align less accurate
Types of GPS jamming threats, unintentional and intentional
Unintentional
- Friendly jamming
- UAV links
- INTELSAT uplink freqs
- Inmarsat encroachment
Intentional
- Noise jamming
- Spoofing
List indications of GPS jamming
Never acquire a position fix
Degraded tracking
Breaklock: loss of pos fix and time transfer
Loss of satellites in view
GPS Jamming vs Spoofing
Jamming:
- Uses noise to deny signal acquisition
- Simple, cheap, affective
Spoofing:
- Requires signal regeneration/manipulation
- Complicated, expensive and unpredictable
- Indications are difficult to discern
- Time is wrong, gross position errors, receiver wanders
Loading the precision codes
Helps slow down jamming
Improves FOM by using both L frequencies
- Using both L frequencies corrects for ionospheric error
Capabilities of GPS
Extremely accurate 3D PVT determination
Passive, day/night, all weather
Real times and continuous information
Supports unlimited users
Common time reference
Limitations of GPS
Dependent on ground stations
Signal can be jammed/spoofed
LOS
Several sources of error: (Not highlighted) Clock, ephemeris, ionosphere, troposphere, receiver, multipath
Describe the purpose of the Kalman filter and how the filter analyzes inputs. 6 steps
- Observe, collect, measure data - GPS, INS, fix; includes error data
- Predict future PVAT
- Compare observation to prediction to calculate errors
- Based on error weight, calculate PVAT
- Track/update errors and compute CEP
- Apply dynamics (ie acceleration) to PVAT
MC-130H system update types
Flyover
NAVAID
Operation-inserted
Radar
IDS BALT, RALT, azimuth
GPS
Position initiate
MC-130J system update types
Visual update
Radar update
NAVAID update
EO-IR update
List the temperature deviation formula
For every 5.5 degrees C the temp at ALT differs from standard day, At (true altimeter) changes 2%
or
For every 10 degrees C greater (or lesser), increase (or decrease) Ai (indicated altimeter) by 3.5%
GPS: Difference between the ellipsoid and the geoid
Ellipsoid is a mathematically defined object that approximates the size/shape of the Earth. Height above the ellipsoid is measure in (h)
Geoid is a physical model of Earth based on MSL and gravity measurements. Height above is the geoid is measured in (H)
Geodetic heights formula
h (GPS) = H (BARO) + N
Target resolutions: Define range resolution and bearing resolution
Range resolution: Ability of a radar to distinguish between two or more targets at the same bearing but different ranges. Depends on PW, RCS, and radar system
Bearing resolution: Ability of a radar system to separate objects at the same range but different bearings. Depends on radar BW and target range
How to calculate range resolution
Use PW, radar with maximum efficiency should be able to distinguish targets separated by one-half the PW time.
RR ft = PW x 492 ft
