Since their introduction in the 1970s and 1980s superresolution systems for point source parameter estimation have received theoretical attention regarding their potential performance. Two aspects of performance in particular are of interest, the accuracy of the parameter estimation and the resolution achievable. Limitations on performance may be considered to be due to noise affecting the data, or to errors in the system. Superresolution methods divide roughly into two groups – ‘spectral’ methods and maximum likelihood (ML) methods. MUSIC is perhaps the most effective example of a spectral method and has been studied in considerable detail, in both performance measures, but mainly only for the case of a single parameter. In this study the accuracy of MUSIC in the application of two-dimensional direction finding (DF) has been analysed, with and without system errors, using a general array. Theoretical results are confirmed by simulations. An aim has been to produce simpler results for use in estimating the potential performance of practical systems. Little work has been reported on the resolution of ML methods and this is the second main topic of this work, particularly for the two-dimensional DF case using a general array, with a ML method (IMP) similar to the better known Alternating Projection. Some results are obtained for resolution with and without errors for the case of noncoherent signals. For coherent signals (including the standard radar case) the performance is found to depend on the relative phase of the signals, varying from the quadrature case, where the performance is as for the non-coherent case, to the in-phase (or antiphase) case where only one signal peak is seen.
| Identifer | oai:union.ndltd.org:bl.uk/oai:ethos.bl.uk:564664 |
| Date | January 2009 |
| Creators | Brandwood, D. |
| Publisher | University College London (University of London) |
| Source Sets | Ethos UK |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
| Source | http://discovery.ucl.ac.uk/18507/ |
Page generated in 0.0122 seconds