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OSWEGO - Avionics Dictionary Category: Electronics and Engineering > Avionic terms Date & country: 11/08/2008, USA Words: 560

Reported.
Data from a device

Ring-laser gyro (RLG).
A gyroscope based on a laser beam instead of a rotating mass, providing to same data as a gyroscope;

RLG.
Ring-laser gyro

RMS.
Root mean square;

RNG.
Range

Roll cue.
Flight director cue to control roll; in fixed-wing aircraft, a wheel cue; in rotary-wing aircraft, a lateral cyclic cue

Roll rate.
Rate of change of roll; time derivative of roll; Symbols: q; Symbols: phi dot; Typical Units: rad/s,deg/s; Dimensions: 1/Time;

Roll.
Bank angle; Symbols: phi,Phi; Typical Units: rad, deg;

Root mean square (RMS).
A statistical measure of data; the root of the mean of the square; for variables with mean of zero, the standard deviation is equal to the rms; Compare: root sum square;

Root sum square (RSS).
A statistical measure of data; the root of the sum of the square; for a vector, its length is equal to the rss of its scalar elements; Compare: root mean square;

Rotary wing.
A helicopter;

RSS.
Root sum square;

RT.
Remote terminal

RTES.
Real-time engineering simulation

RTU.
Remote Terminal Unit

Rudder.
A control surface on fixed-wing aircraft, usually mounted at aft end of the fuselage sticking up (like a dorsal fin), that controls yaw (heading), and is controlled by the pedals; Symbols: delta sub R; Typical Units: rad, deg;

Sampling frequency.
Rate of a periodic process; 1/T where T is the period; Symbols: f sub s; Typical Units: Hz; Dimensions: 1/Time.

SDC.
Signal Data Converter

Search pattern.
Basic guidance mode; provides lateral steering guidance to fly an expanding square search pattern, creeping line search pattern, or sector search pattern.

Second-order filter.
A smoothing filter in which the output follows the input, only more slowly; It is usually implemented in software as a difference equation of period T. When the second-order filter is used in avionics, it is commonly to smooth data, and to wash out transients at mode change. Usually, a first-order filter suffices, and it being less expensive, is ch...

Sector search.
A pattern of concentric arcs followed for searching the ground from an aircraft; Compare: creeping line search, expanding square search;

Selected.
Measured data picked from one of many sensors; Selecting is the process of choosing the 'best' parameter from multiple copies of that parameter, from multiple, identical devices or similar devices. Compare: derived, estimated, filtered, measured, raw, smoothed

Selftest.
A test internal to a device

Semi-circle.
A measure of angle, 1 semi-circle = pi rad = 180 deg; angles from physical devices are often reported in semi-circles in order to compress data

Sensor Fusion/Correlation (SFC).
Measure of convergence of sensor data

Sensor.
A device that measures, receives, or generates data, for example, an INS, a FLIR, a map. See Also: Data Source Object

SEP.
Spherical error probability

SFC.
Sensor Fusion/Correlation

Shutdown.
To cease normal operations

Sideslip angle.
Symbols: beta; Typical Units: rad, deg;

Signal Data Converter (SDC).
A device that converts unique signals to a standard protocol, usually MIL-STD-1553B; Synonyms: Remote Terminal Unit;

Signal-to-noise ratio (SNR,S/N).
A ratio of magnitude of a desired signal to the magnitude of the noise received with it; Typical Units: dB;

Signal.
Part of received data that is desired; Compare: noise, offset

Situational awareness.
Situational awareness provides the pilots with information relative to the current surroundings, such as other aircraft or threats in the immediate area.

Slant range.
Direct line distance, not along the ground;

Slats.
A control surface on fixed-wing aircraft, usually mounted to the aft edge of the wings, that extends the wing to provide added lift at low speeds; Compare: flaps; Symbols: delta sub S; Typical Units: rad, deg;

Smoothed.
Data that is the result of conditioning a signal with a simple filter; Compare: derived, estimated, filtered, measured, raw, selected; smoothing is usually less sophisticated than filtering

Smoothing filter.
A filter to reduce quick changes of a signal by attenuating high frequencies; See Also: first-order filter, second-order filter, wash-out filter;

SNR.
Signal-to-noise ratio

South American.
A standard model for computing earth data

Speed cue.
Flight director cue to control speed; in fixed-wing aircraft, a throttle cue; in rotary-wing aircraft, a longitudinal cyclic cue

Speed error.
A basic output from guidance to flight director, indicating the difference between actual speed and desired speed; Symbols: DELTA V; Typical Units: ft/s,kt; Dimensions: Length / Time.

Speed.
Scalar velocity;

Spherical error probability (SEP).
A probability that a percentage of three-dimension measurements will lie within a sphere of given radius, with the sphere centered at truth or mean of the measurements; SEP specifies test cases for measurement errors of sensors of three dimensions, such as velocity east, north, and vertical. Compare: circular error probability, radial error probabi...

Spoiler.
A control surface on fixed-wing aircraft, usually mounted to the wings, that provides roll control and lift; Symbols: delta sub S; Typical Units: rad, deg;

Stability coordinates.
Coordinates referenced to the air mass; Compare: body coordinates, earth coordinates;

Stabilizer.
A control surface, usually mounted at aft end of the fuselage parallel to the wings, that provides pitch stability, some aircraft have an adjustable stabilizer; Symbols: delta sub H; Typical Units: rad, deg;

Stagnation pressure.
Total pressure

Standard units.
Units commonly encountered for a particular quantity;

State data.
Data that defines aircraft parameters, such as position, velocity, attitude; Some standard terms for state data include: Groundspeed vector, wind speed vector, true airspeed vector, true bearing, true track, ground track angle, relative bearing, sideslip angle, drift angle, true heading, magnetic variation, grivation. earthspeed vector, vertical ve...

State-space model.
A mathematical relationship of a system in time using state variables, inputs, outputs, and constants; The state-space model is composed of n state variables (x sub 1 , x sub 2 , ..., x sub n), m input variables (u sub 1 , u sub 2 , ..., u sub m), k output variables (y sub 1 , y sub 2 , ..., y sub k), and four constants a, b, c, and d. Alternativel...

Static pressure.
A measure of barometric pressure as if the sensor were not moving with respect to the air; Compare: total pressure; Symbols: p sub s; Typical Units: psi,lbf/in-squared; Dimensions: Mass /Time-squared * Length

Station.
A structure on the ground, perhaps containing VOR or TACAN

Status indicator.
An binary indicator of a particular aspect of a device; status indicators are independent of each other; status indicators listed in this dictionary are derived from existing programs. See Also: off, warning, operations, communications, useability, initialization, test, maintenance, unknown;

Status words.
Data words reported by devices to indicate status; Each bit is defined on a device-by-device basis. The number of words vary from device to device. Status words are used by maintenance personnel and maintenance software. Present, past, and test status words are reported.

Status.
An indicator of how well a system or subsystem is working

Strapdown inertial sensor.
Accelerometers mounted to a platform fixed to the aircaft; Compare: gimbaled inertial sensor

Surface Wind Wave Motion (SWWM).
..

Surface.
Related to surface of water;

Survivability.
A survivability subsytem detects and counters hostile actions.

Swashplate.
A device to control the pitch of rotors; on rotary-wing aircraft, the swashplate is controlled by a collective and a cyclic;

SWWM.
Surface Wind Wave Motion

System.
Applied to measurements, means the best value that the system can determine.

TA.
Terrain avoidance

TACAN Point-to-Point (TCNP).
A basic guidance mode, providing lateral guidance to a point relative to a TACAN station by specified range and bearing;

TACAN.
Tactical Air Navigation;

Tachometer.
A device for measuring angular velocity;

Tactical Air Navigation (TACAN).
A basic guidance mode, providing lateral guidance to a TACAN station; Equipment that determines range and bearing to a radio station with a TACAN transmitter;

TAE.
Track angle error

Target cursor.
A symbol on a display, moved by a track handle or similar device, to select objects on the display

Target.
Object or point pointed by FLIR or radar

TAS.
True airspeed

Taut line.
Basic guidance mode; provides vertical guidance to maintain a taut line for a dipping sonar, or other such device.

TCN.
Tacan

TCNP.
Tacan Point-to-Point

Terrain avoidance (TA).
Flight such that the aircraft maintains a constant barometric altitude but flies around obstacles; Compare: obstacle avoidance, threat avoidance;

Terrain following (TF).
A basic guidance mode, providing vertical guidance to maintain an operator selected radar altitude above the terrain. Flight such that the aircraft tries to maintain a constant height above the terrain, usually in the range of 100-1,000 ft; Uses a g-command from the Multi-Mode Radar to generate a flight director cue. This controls the aircraft flig...

Terrain.
The contour of the earth;

Test status words.
Status words reported at the conclusion of a test. Values: test in progress, not tested, normal, redundant, degraded, failed;

TF.
Terrain following;

ThA.
Threat avoidance

Threat avoidance (ThA).
Flight cues designed to avoid enemy threats, such as anti-aircraft artillery and aircraft; Compare: obstacle avoidance, terrain avoidance;

Throttle cue.
A longitudinal flight director cue for fixed-wing aircraft, primarily to control speed, by changing power; Compare: longitudinal cyclic cue; Symbols: Gamma sub LONG; Typical Units: percent,in;

Throttle.
A flight control operated by moving fore or aft with hands, primarily to control thrust (speed) in fixed-wing aircraft;

Thrust.
Force, created by engines and rotors, acting in the direction of the engine; Symbols: T; Typical Units: lbf,kip; Dimensions: Mass * Length / Time-squared;

Tilt rotor.
An aircraft with tilting rotors for fixed-wing flight or rotary-wing flight;

Time constant.
Constant for a first-order filter determining time at which the output of the filter reaches nearly 0.6321 percent of a step input; Symbols: tau; Typical Units: s; Dimensions: Time;

Tolerances.
Allowed error in measurements

Total pressure.
A measure of barometric pressure in the moving air; Synonyms: dynamic pressure, Pitot pressure, stagnation pressure; Compare: static pressure; Symbols: p sub t; Typical Units: psi,lbf/in-squared; Dimensions: Mass /Time-squared * Length

Track (TRK).
A basic guidance mode, providing lateral guidance to an operator selected ground track;

Track angle error (TAE).
A guidance control law parameter, generated by the lateral guidance modes; Typical Units: rad;

Track angle error gain (KTAE).
A guidance control law parameter, generated by the lateral guidance modes;

Track handle.
A device to move a cursor in two axes on a display, much like a mouse

Tracking.
Tracking is performed by the TRN

Transceivers.
A device that receives and transmits

Transient-free switch.
A switch with a wash-out filter so that the output contains no transients (steps) at switch time

Transmit.
To radiate RF energy

Transmitter.
A device that transmits

Trim tab.
A secondary control surface, usually mounted to primary control surface such as aileron, elevator, rudder, or stabilizer, that controls the position of the primary control surface, and is controlled by the an operator or an autopilot; Symbols: delta sub T; Typical Units: rad, deg;

TRK.
Track