240 results about "Twiddle factor" patented technology

The invention discloses a virtual array DOA estimation method based on an L type array. The method comprises the steps that 1, based on the shift invariant property, a subarray Zx and a subarray Zy of the L type array horizontally shift to obtain a virtual array Zx' and a virtual array Zy', rotation invariance of two sub signals is formed due to the shift invariant property of the subarrays, and the virtual subarray signals are equal to the L type subarray Zx and L type subarray Zy input signals multiplied by a twiddle factor respectively; 2, the output of the four subarrays are combined to form a virtual array output signal Z (t); 3, the signal subspace and the noise subspace can be described by decomposing the features of covariance matrixes output by the array, mutual correlation processing is carried out on the array output signal Z(t) to obtain Rzz, and eigenvalue decomposition is carried out to obtain signal subspaces; 4, the twiddle factor is solved through linear operation, and the signal wave arrival direction can be obtained through the diagonal element of the twiddle factor. According to the virtual array DOA estimation method, no spectral function needs to be calculated, the phenomenon that the wave arrival direction is indirectly calculated without searching for the peak value is avoided, the complexity is lowered, the equipment complexity and cost are reduced, and the positioning precision is high.

The invention relates to a phase correction apodization method for a Fourier transform spectrometer. In the method, by weighting a zero-crossing single-sided interferogram, the errors caused by utilizing data near a zero optical path difference point in the calculation process twice are reduced. The method has better weighting effects than an apodization method provided by Mertz, the accuracy of a recovery spectrum can be ensured, and the calculation complexity is effectively reduced simultaneously. After the zero-crossing single-sided interferogram is weighted by the apodization method provided by the invention, the sum of products of light intensity of two corresponding points with the same optical path difference in a short double side of the zero-crossing single-sided interferogram and respective corresponding twiddle factors is an average value of the sum of the products of the light intensity of the two corresponding points and respective corresponding twiddle factors before weighting. Thus the calculation errors brought by asymmetry of the interferogram are reduced, and a more precise recovery spectrum is obtained.

A fast Fourier transform processor using a single delay path and a permuter provides a reduction in the implementation area and a related reduction in power consumption through efficiencies obtained by the modification of a butterfly unit and the use of a novel interleaver. The modified butterfly unit is obtained by the removal of complex variable multipliers, which is possible due to the simplification of twiddle factors in the stages that correspond to the modified butterfly unit.

A Fast Fourier Transform (FFT) processor is provided. It comprises a multiplexer, a first angle rotator, a second angle rotation and multiplexing unit, an adder, a twiddle factor storage, a multiplier, and a data storage. The FFT processor analyzes the input / output order of the Fast Fourier Transformation, separates the portions requiring complex computations, simplifies the hardware thereof, and adjusts the output order. It not only effectively saves the hardware area, but also reduces the computations and memory access count. Thereby, the power consumption is reduced.