![]() NASA Technical Reports Server (NTRS)Chervenak, Ann L. Experiments validating the theoretical conclusions as well as the effectiveness of the proposed scheme have been included. Moreover, an effective countermeasure against the cases of singular mixtures has been proposed, on the basis of previous analysis. Results and conclusions obtained should be instructive when applying ICA algorithms on mixtures from sensor arrays. The situations where the mixing process turns (nearly) singular have been paid special attention to, since such circumstances are critical in applications. We analyze the analytic relationship between the noise variance, the source variance, the condition number of the mixing matrix and the optimal signal to interference- plus- noise ratio, as well as the relationship between the singularity of the mixing matrix and practical factors concerned. Factors taken into consideration include the environment noise level, the properties of the array and that of the radiators. In this manuscript, the issue is researched by taking the typical antenna array as an illustrative example. While sensor arrays are involved in most of the applications, the influence on the performance of ICA of practical factors therein has not been sufficiently investigated yet. ![]() The the parameter can be determined simply from: The resulting Array Factor ( AF) will have the minimum null-null beamwidth for the specified sidelobe level, and the sidelobes will all be equal in 2.com › Matlab Program For Dolph Chebyshev Array Worksheets █ █ █ ![]() ![]() ![]() Suppose there are N elements in the array, and the sidelobes are to be a level of S below the peak of the main beam in linear units (note, that if S is given in dB, it should be converted back to linear units SdB=20.log( S), where the log is base-10). The parameter is used to determine the sidelobe level. We can now match this polynomial to the corresponding Tschebyshef polynomial (of the same order), and determine the corresponding weights. To do this, we'll recall some trigonometry which states relations between cosine functions: If we substitute these expressions into the Antenna Array Factors given in equations (1) and (2), and introduce a substition: we will end up with an AF that is a polynomial. Using the complex-exponential formula for the cosine function: The array factors can be rewritten as: Recall that we want to somehow match this expression to the above Tschebyscheff polynomials in order to obtain an equil-sidelobe design. ![]()
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