DIGITAL BEAM-FORMING TECHNIQUE USING TEMPORARY NOISE INJECTION

摘要

An efficient digital beam-forming network (100) utilizing a relatively few small-scale A/D converters is disclosed herein. The inventive beam-forming network (100) is disposed to generate an output beam B in response to a set of N input signals. The set of input signals is provided by an antenna array (110) having N elements, upon which is incident an electromagnetic wavefront of a first carrier frequency. The present invention includes an orthogonal encoder circuit (170) for generating a set of N orthogonal voltage waveforms. A set of biphase modulators (162-168) modulates the phase of each of the input signals in response to one of the orthogonal voltage waveforms, thereby generating a set of N phase modulated input signals. The N phase modulated input signals are combined within an adder (180) to form a composite input signal. The inventive network (100) further includes a downconverting mixer (184) for generating an IF input signal in response to the composite input signal. The IF input signal is then separated into baseband in-phase and quadrature-phase components by an I/Q split network 192. A pair of A/D converters (198, 200) then sample the in-phase and quadrature-phase components of the input signal. A decoder (202), coupled to the orthogonal encoder circuit (170), provides decoded digital in-phase signals and decoded digital quadrature phase signals in response to the digital in-phase and quadrature-phase signals. The present invention further includes a digital beam-former (130) for generating the output beam B by utilizing the decoded in-phase and quadrature-phase signals.