Commonwealth Scientific and Industrial Research Organisation

Colin Eric Jacka

John David Bunton

Graham Ross Daniels

John D O'Sullivan

Kien T Hua

David R Brown

A communications system, including at least one base station () at the surface, at least one repeater station () below the surface, and at least one mobile station () below the surface, the stations () establishing a bidirectional communications path between the mobile station () and the base station ().

Communications system

The elements of a transform processing circuit are switchable to change the order of data in a data stream and/or to perform a fast Fourier transform (FFT) or inverse fast Fourier transform (IFFT) on the data stream. Each arithmetic circuit element performs an M-point butterfly operation on complex sample points and includes an adder/subtractor and a serial memory capable of storing M/2 sample points. Each multiplication unit performs an n-point complex twiddle factor operation on its input. The conjugator units conjugate inputted sample points. All circuit elements are connected to buses by switches. These connections are switchable so that in one switch state data input at left terminal flows to right terminal and in another state data input at right terminal flows to left terminal. The state of the bus switches also determines whether the circuit performs a FFT, an IFFT, or a bit reversal operation on input data. Transfer processing circuit may be incorporated into an integrated circuit together with a complex multiplier and a multiplexer, the integrated circuit is capable of performing FFT and IFFT operations on vectors or on transformed vectors and is capable of performing vector multiplication.

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North Turramurra, Australia

Colin Eric Jacka