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Radar beacon. Racon signal as seen on a radar screen. This beacon receives using sidelobe suppression and transmits the letter "Q" in Morse code near Boston Harbor (Nahant) 17 January 1985. Radar beacon (short: racon) is – according to article 1.103 of the International Telecommunication Union's (ITU) ITU Radio Regulations (RR) [1 ...
When a target is marked by a designator, the beam is invisible and does not shine continuously. Instead, a series of coded laser pulses, also called PRF codes (pulse repetition frequency), are fired at the target.
Direction finding ( DF ), or radio direction finding ( RDF ), is the use of radio waves to determine the direction to a radio source. The source may be a cooperating radio transmitter or may be an inadvertant source, a naturally-occurring radio source, or an illicit or enemy system.
Doppler radio direction finding. Doppler radio direction finding, also known as Doppler DF, is a radio direction finding method that generates accurate bearing information with a minimum of electronics. It is best suited to VHF and UHF frequencies and takes only a short time to indicate a direction. This makes it suitable for measuring the ...
A Bellini–Tosi direction finder ( B–T or BTDF) is a type of radio direction finder (RDF), which determines the direction to, or bearing of, a radio transmitter. Earlier RDF systems used very large rotating loop antennas, which the B–T system replaced with two fixed antennae and a small rotating loop, known as a radiogoniometer.
The radar scans a 90-degree sector for incoming rocket, artillery and mortar fire. Upon detecting a possible incoming round, the system verifies the contact before initiating a track sequence, continuing to search for new targets.
A coincidence rangefinder or coincidence telemeter is a type of rangefinder that uses the principle of triangulation and an optical device to allow an operator to determine the distance to a visible object. There are subtypes split-image telemeter, inverted image, or double-image telemeter with different principles how two images in a single ...
Refractive index. A ray of light being refracted through a glass slab. In optics, the refractive index (or refraction index) of an optical medium is a dimensionless number that gives the indication of the light bending ability of that medium. Refraction of a light ray. The refractive index determines how much the path of light is bent, or ...
A basic lidar system involves a laser range finder reflected by a rotating mirror (top). The laser is scanned around the scene being digitized, in one or two dimensions (middle), gathering distance measurements at specified angle intervals (bottom).
A director's viewfinder or director's finder is a viewfinder used by film directors and cinematographers to set the framing of a motion picture or movie camera. There are three types of director's viewfinders.