Abstract: An apparatus for performing a Fourier transform using Cordic techniques. Digital words are pipelined through serial add/subtract stages to provide vector rotations without trignometric lookup tables or multiply operations. The throughput of an FFT butterfly calculation is increased over prior art digital processors. A plurality of apparatus may be pipelined in a system to further increase the throughput rate. Also, the apparatus may be programmed to perform vector rotations through a plurality of angles thus providing the capability to compute FFT's of varying numbers of points.

Abstract: In a navigation system in which a beam of radiation is utilized for communicating information to a vehicle, such as an aircraft approaching a landing strip, there is provided a pseudo-noise generated binary code having sequentially generated bits ordered in a sequence of nonrepeating subsequences with each of these bits uniquely representing a value of a coordinate describing the position of the beam of radiation. For example, with an azimuthally scanned beam of radiation, each bit in the code represents an increment in the azimuth angle while the digits of one of the subsequences is sufficient to uniquely determine the azimuth angle. An encoder and a decoder, each similarly structured with a shift register and feedback logic, are disclosed.