gps

What is an inertial navigation system (INS)

heading reference system that uses dead reckoning method of navigation

Define Dead Reckoning

process of estimating present position from known info

gyroscope

mechanical device containing a spinning mass universally mounted

The INS keeps track of and NOT __

position, total distance traveled

What kind of info does the INS provide?

Position

Inertial Navigation Unit: Platform Assembly

Sensors detect aircraft acceleration and altitude

Inertial Navigation Unit: Digital Computer

integration of platform signals

Air Data Computer

Provides barometric altitude, true airspeed, & magnetic heading to the INU

Digital Data Computer

performs interfacing between INS and other subsystems

EEC

Provides present position, elevation, and magnetic variation

Compass Controller

Provides switching functions, latitude compensation signals, and slew signals to the system compass adapter

Glide path

Predetermined imaginary path to the landing strip in the horizontal plane

Glide Slope

Predetermined imaginary path to the landing strip in the vertical plane

GPS is accurate in what dimensions?

Latitude

Longitude

Altitude

Identification Friend or Foe

Allows friendly craft to identify itself

reports altitude info to ground air control RADAR

operates up to 300 miles

Coder synchronizer unit

Synchronized to the radar system transmitter.

-fires 1 to 40 microseconds after the radar transmitter pulse

Transponder unit

-transmits reply pulses to the interrogator

-usually resides in aircraft

degress of freedom

Number of axis rotor is free to process

Define velocity

result of acceleration when intergraded with time

What is mechanical drift?

Slow procession caused by random inaccuracies

What is rate gyroscopes?

Restrained gyroscope with one degree of freedom

What is floated gyroscope?

Unit uses a restrained called a torsion bar

Accelerometer

Device that measures acceleration and develops proportional signal.

What are the types of accelerometers

Basic, E-Transformer, pulse continuing.

What is rigidty?

Ability of a gyroscope to keep axis fixed in space.

What is precession?

Rotation of spin axis of a gyroscope in response to attempt to move spin axis. Direction is always perpendicular.

What are the 3 directions an accelerometer is pointed?

North, East and vertical.

Define ground alignment mode

Mode of operation establishes the referenced which the INS determines aircraft altitude and measures acceleration to computer aircraft position.

Altitude heading references system (AHRS)

Supplies the flight instruments for pilot referencing with inputs representing Pitch, roll and yaw.

Displacement gyroscope

Hermetically sealed, two gyroscope platform providing pitch, roll and azimuth signals to the systems indication instruments.

Compass transmitter flux value

Senses the directions of the earths magnetic field and develops a proportional signal.

Compass mode (Comp)

Emergency mode used when the displacement gyroscope malfunctions.

Free mode (free)

Used at latitudes greater than 70 degrees.

Slaved mode (Salve)

Normal operation mode that uses both flux value and directional gyroscope signals

Angle of attack (AOA)

Angle between the chord line of an airfolc and the relative land

Automatic carrier landing system (ACLS)

Aids pilot in safely landing aircraft about an aircraft carrier. Does NOT guarantee perfect landing.

Data link

Pitch and roll commands that are used to intercept and lock onto landing pattern, data link commands that establish proper glide path

Landing control central system (LCCS)

Radar tracks aircraft and compass position to desired glide path

LCCS Mode 1

Fully automatic from entry point to touchdown

LCCS mode 2

Manual control of aircraft by pilot using cockpit displays

LCCS mode 3

Manual pilot control with talk down guidance by shipboard controller

ACLS Mode 1

Landing operation, pilot switches to ACL and verbally acknowledges engagement of autopilot.

Safety Provisions during ACLS mode 1

• Couple signal transmission ceases

• Auto pilot disengages

• Pilot must revert to mode II or III

Global Positioning System

• Navigation within 10 meters in 3D

• Velocity withing .1 meters/sec

• Time within 100 nanoseconds

• GPS Satellites use automatic clock w accuracy to approx

• 1 second per 20 million years

GPS System provides:

Passive operation, all-weather operations, real time position, continuous operation, usability in hostile environments, infinite number of users.

Aviation GPS

Vital for streaming en route, terminal and approach navigation. Reducing flight and saving fuel and money

GPS Signal and Data flow

2 RF signals called link 1 (l-1) and link 2 (L-2). Antenna controller separates, amplifies and converts signals.

Identification: Friendly or foe

• Permits friendly craft to ID itself automatically

• Reports altitude info to ground ATC radar

• Range is approx 300 miles

Interrogator unit

Pulse type transmitter that is triggered by coder synchronizer

Coder Synchronizer unit

Synchronized to the radar system transmitter. Fires 1 to 400 milliseconds after Rader transmitter pulse.

Transponder unit

Transmits reply pulses to the interrogator

Search radar unit

Initiates trigger pulse and radar video for unidentified craft.

IFF mode 1

Used for general ID of military aircraft only

IFF mode 2

Used for personal ID

IFF mode 3

Used in conjunction with ATC

IFF mode 4

Classified secure mode of operation

IFF mode C

Provides altitude INFO

IFF mode 4 computer

Allows IFF transponder to respond to secure mode 4 interrogations.

How long are interrogation pulses

0.8 - 11 Usec

What is the framing for information pulses?

45 Usec wide and 1.45Usec Apart

What is I/P (Identification of position)

Switch on EEC is pressed. Lasts for 15-30 seconds in mode 1 2 and 3A

What is emergency operation

• IFF master switch is set to EMERG

• Enabled when pilot Ejects

• Modes 1,2 and 3A are enabled to reply

• Mode 3A code becomes 7700

• Mode 4 operation is not affected by EMERG

• Overrides Emcon

What provides false reading or dangerous potentials even if power is off?

AN/ARN 151 LAN