Digital frequency-domain implementation of arrays

A method for the digital frequency domain implementation of transmitting arrays comprising the steps of:

• transforming a discrete time input signal into its spectral components;
• removing redundant spectral components;
• computing a first set of products, for each channel of the array, of non-redundant spectral components with a scaled set of acquired weights;
• deriving from said first set of products a second set of products for each channel of the array;
• and
• converting said first and second sets of products to a discrete time output signal in each channel.

A system for the digital frequency domain implementation of receiving arrays which offers improved resolution in both direction and frequency determination without necessitating sampling rates of the received signal much higher than the Nyquist rate, said receiving arrays having receiving elements, each receiving element defining a channel, said system comprising:

• spectral transforming means for transforming a discrete time input signal in each channel into N spectral components using an N-point discrete Fourier transform;
• spectrum filtering means responsive to said spectral components and capable of passing, in each channel, non-redundant spectral components only;
• computational means for deriving for said non-redundant spectral components in each channel a set of weights comprising weights that are scaled both in amplitude and in phase, so that said set of weights corresponds to .alpha.N spectral components, where .alpha. is an integer power of 2;
• computational means for computing products of said non-redundant spectral components in each channel with said scaled weights for each channel;
• summing means for calculating from the said computed products a first set of spectral sums;
• computational means for deriving from said first set of spectral sums a second set of spectral sums;
• and
• processor means for converting said first and second sets of spectral sums to the discrete time domain, using an inverse Fourier transform based on a pruned decimination-in-frequency structure fast Fourier transform, thereby obtaining a discrete time output signal.

A system for the digital frequency domain implementation of transmitting arrays comprising:

• spectral transforming means for transforming a discrete time input signal into its spectral components;
• spectrum filtering means responsive to said spectral components and capable of passing non-redundant spectral components only;
• computational means for computing a first set of products, for each channel of the array, of said non-redundant spectral components with a scaled set of acquired weights;
• means for deriving from said first set of products a second set of products for each channel of the array;
• and
• processor means for converting said first and second sets of products to a discrete time domain output signal in each channel of the array.