Method and System for Determining Signal Direction

Abstract

Methods and systems for the efficient determination of the direction of multiple signal sources in both near and far field using hierarchical combinations of sets of raw input signals to convert spatial input to angular output. Each increasing hierarchical combination increases angular resolution, improving image quality with low computational expenditure.

What is claimed is: 
     
         1 . A method for interpreting beam direction imaging data comprising:
 acquiring a first plurality of raw input signals from a first set of neighboring transducers in a phased array;   combining the first plurality of raw input signals to form a first set of output angular signals;   acquiring a second plurality of raw input signals from a second set of neighboring sensors in the phased array;   combining the second plurality of raw input signals from the second set of neighboring sensors in the phased array to form a second set of output angular signals;   combining angles of interest from the first set of output angular signals with the second set of output angular signals to refine angular resolution; and   wherein the angles of interest from the first set of output angular signals and the second set of output angular signals may be combined in a plurality of different independent ways to refine angular resolution and improve image quality.   
     
     
         2 . The method of  claim 1 , wherein the imaging data is near field imaging data. 
     
     
         3 . The method of  claim 1 , wherein the imaging data is far field imaging data. 
     
     
         4 . The method of  claim 1 , wherein the angles of interest from the first set of output angular signals and the second set of output angular signals may be combined pairwise in increasing levels of hierarchy until a spatial input from the phased array is converted to angular information of resolution at an Abbe limit. 
     
     
         5 . The method of  claim 1 , wherein, the raw input is apodized. 
     
     
         6 . The method of  claim 1 , wherein a sample frequency generating the first plurality of raw input signals and the second plurality of raw input signals is at least two times per wavelength. 
     
     
         7 . The method of  claim 1 , wherein a sample frequency generating the first plurality of raw input signals and the second plurality of raw input signals is four times per wavelength. 
     
     
         8 . The method of  claim 1 , wherein a sample frequency generating the first plurality of raw input signals and the second plurality of raw input signals is less than ten times per wave length. 
     
     
         9 . The method of  claim 1 , wherein there are a first plurality of frequencies generating the first plurality of raw input signals. 
     
     
         10 . The method of  claim 1 , wherein there are a second plurality of frequencies generating the second plurality of raw input signals. 
     
     
         11 . The method of  claim 1 , wherein the plurality of frequencies generating the first plurality of raw input signals and the second plurality of raw input signals first and second raw input signals are the same. 
     
     
         12 . The method of  claim 1 , wherein the plurality of frequencies generating the first plurality of raw input signals and the second plurality of raw input signals are different. 
     
     
         13 . The method of  claim 1 , wherein the beam directions are determined in parallel. 
     
     
         14 . The method of  claim 1 , wherein the transducers are less than a wavelength apart. 
     
     
         15 . The method of  claim 14 , wherein the transducers are less than 0.7 wavelengths apart. 
     
     
         16 . A method of generating a multi-dimensional image from a phase array with one less dimension than the multi-dimensional image comprising:
 receiving a signal of amplitude (A) from an array of sensors over time (t);   apodizing received signals A;   pairing each signal A received by a sensor with an adjacent signal above, below and across forming a first set of paired signals B;   compensating for the time delay due to location difference of each sensor receiving the signal;   pairing each pair in the first set of paired signals B in accordance with their spatial placement and angle in volume in the phase array to form a second set of paired signals C;   pairing each pair in the second set of paired signals C in accordance with their spatial placement and angle in volume in the phase array to form a third set of paired signals D;   wherein the third set of paired signals D produce the multi-dimensional image.   
     
     
         17 . A beamforming apparatus comprising:
 a phased array comprising transducers separated by a distance L configured to receive signals of a frequency (f) with a period (T) and wherein there is a time delay of +t/4 to −t/4 between signals received by adjacent transducers;   a processor configured to translate spatial input data to angular output by:
 pairing each received signal according to space and time to create a first set of paired received signals; 
 pairing each of the first set of paired received signals according to space, angle and time to create a second set of paired signals; 
 pairing each of the second set of paired signals according to space, angle and time to create a third set of paired signals; 
 pairing each of the third set of paired signals according to space, angle and time to create a fourth set of paired signals; 
 continuing hierarchically to combine angles of interest with adjacent angular beams from neighboring sub-arrays to refine angular resolution until all of the spatial input has been converted to angular information of resolution at an Abbe limit; 
   apodizing each set of signals;   interpolating the angular information; and   forming an image from the interpolated angular information; and   wherein, all possible beam directions are detected in parallel.   
     
     
         18 . The beamforming apparatus of  claim 17 , wherein the distance L is λ/1.44. 
     
     
         19 . The beamforming apparatus of  claim 17 , wherein a beam angle varies between +π/4 radians to −π/4 radians. 
     
     
         20 . The beamforming apparatus of  claim 17 , wherein the beamforming apparatus is frequency agnostic.