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High-frequency direction finding, usually known by its abbreviation HF/DF or nickname huff-duff, is a type of radio direction finder (RDF) introduced in World War II. High frequency (HF) refers to a radio band that can effectively communicate over long distances; for example, between U-boats and their land-based headquarters.
A number of transmitters, from Lossiemouth to Manston in Kent transmitted on slightly different frequencies transmitted a narrow beam across the North Sea using a S.B.A. (Standard Beam Approach) transmitter, receivers for-which were fitted to all British bombers and could be received over a range of 350 miles at 10,000 feet. Once a bomber found ...
A portable, battery operated GT-302 Accumatic automatic direction finder for marine use. Radio direction finding, radio direction finder, or RDF, was once the primary aviation navigational aid. (Range and Direction Finding was the abbreviation used to describe the predecessor to radar. [2])
A great advance in RDF technique was introduced in the form of the Bellini-Tosi direction finder (B-T) system, which replaced the rotation of the antenna with the rotation of a small coil of wire connected to two non-moving loop antennas. The loop antennas were similar to those used in earlier systems but fixed in position, set at right angles ...
Ultra high frequency (UHF) is the ITU designation [1] for radio frequencies in the range between 300 megahertz (MHz) and 3 gigahertz (GHz), also known as the decimetre band as the wavelengths range from one meter to one tenth of a meter (one decimeter).
The degree of rotation of the compensator determines the range to the target by simple triangulation. [1] Coincidence rangefinders made by Barr and Stroud used two eyepieces, and may be confused with stereoscopic units. The second eyepiece showed the operator a range scale so the user could range and read the range scale simultaneously. [2] [3]
Those RTs with power settings can vary transmission range from approximately 200 meters (660 feet) to 10 kilometers (km) (6.2 miles). Adding a power amplifier increases the line of sight (LOS) range to approximately 40 km (25 miles). (These ranges are for planning purposes only; terrain, weather, and antenna height can affect transmission range.)
Motorola T5320 FRS handheld radio. The Family Radio Service (FRS) is an improved walkie-talkie radio system authorized in the United States since 1996. This personal radio service uses channelized frequencies around 462 and 467 MHz in the ultra high frequency (UHF) band.