Radar terms, and definitions

Track: Operational phase of a fire-control or track radar during which the radar beam is kept on the target.

Track Radar: Radar that provides continuous range, bearing, and elevation data by keeping the RF beam on the target.

Tracking Radar: A radar whose prime function is to track a radar target and determine the target coordinates (in range and angular position) so a missile may be guided to the target, or a gun aimed at the target. Also refer to the antenna dictionary which contains the definition of a Tracking Antenna. Tracking Radar

Tracking Radar

Tracking Radar Receiver: These are of two primary types: conical scan and monopulse. The conical scan system directs the radar signal in a circle around the target. The radar paints this circle 15 to 40 times per second. As the target moves out of the center of this circle, the radar develops aim error voltages and re-aims the antenna. The monopulse system directs four beams at the target simultaneously. The target is in the middle of the four beams. If the target is not in the center, the radar return develops an aim error voltage to re-aim the antenna.

Track While Scan Radar: [TWS] Provides complete and accurate position information for missile guidance. In one implementation it would utilize two separate beams produced by two separate antennas on two different frequencies. The system utilizes electronic computer techniques whereby raw datum is used to track an assigned target, compute target velocity, and predict its future position, while maintaining normal sector scan. Most aircraft use only a single antenna.

Transient: A phenomenon (such as a surge of voltage or current) caused in a system by a sudden change in conditions, and which may persist for a relatively short time after the change (sometimes called ringing).

Transmit-Receive Tube: Gas-filled rf switch that is used as a duplexer.

Transmitter: Equipment that generates, amplifies, and modulates electromagnetic energy.

Transponder: A transmitter-receiver capable of accepting the electronic challenge of an interrogator and automatically transmitting an appropriate reply. There are four modes of operation currently in use for military aircraft. Mode 1 is a nonsecure low cost method used by ships to track aircraft and other ships. Mode 2 is used by aircraft to make carrier controlled approaches to ships during inclement weather. Mode 3 is the standard system used by commercial aircraft to relay their position to ground controllers throughout the world. Mode 4 is IFF. See also IFF.

Traveling-Wave Tube Amplifier: The TWT is a microwave amplifier capable of operation over very wide bandwidths. In operation, an electron beam interacts with a microwave signal which is traveling on a slow wave helical structure. The near synchronism of the beam and RF wave velocities results in amplification. Bandwidths of 3:1 are possible. Operation at high powers or at millimeter wavelengths is possible at reduced bandwidths.

Traverse Bearing Signal: In a monopulse radar system, the combination of individual lobe signals that represents target offset direction and amplitude from the antenna axis.

Trigger Pulse. A pulse used to cause a circuit to perform some function or initiate specific events.

True North. Geographic north. For reference also refer to Definition of Magnetic Declination, which has a relationship to the term.

Tunnel Diode: The tunnel diode is a heavily doped P-N junction diode that displays a negative resistance over a portion of its voltage-current characteristic curve. In the tunneling process, electrons from the p-side valence bands are able to cross the energy barrier into empty states in the N-side conduction band when a small reverse bias is applied. This diode is used as a microwave amplifier or oscillator.

Twinax: Connector, Two side by side leads surrounded by a shield. A coax line with two conductor leads. Twinax Definition

Two-Dimensional Radar. Measures the range and bearing to a target.