High speed digital signal processing application for a multi-target tracking antenna

Modern radar and communication systems operate in a restricted electromagneticspectrum that is becoming progressively more dense and hostile due to a majorescalation in the number of intentional and unintentional interfering sources. Thereforedemands on antenna performance are increasing with emphasis being directed towardshigh performance and sophistication at low cost.Electronically steered antennas based on phased array antenna techniques offerhigh performance and a range of capabilities that conventional mechanical systems cannot match. However, in the past, such systems tended to be complex, bulky andexpensive and therefore only saw applications in the military and aerospace industries.Continuing technical developments in microwave integrated circuits and printed circuittechnologies have now made it economically feasible to consider applying phased arrayantenna techniques to microwave surveillance and communication systems. Further, withadvances in digital signal processing and high speed digital electronics, a new andexciting application has emerged - that of digital beamforming.This project concentrated on developing high speed digital signal processingtechniques for digital beamcontrol, beamforming and interference suppression.Applications of these techniques were made on an experimental linear phased array thatcomprised of: an eight element microstrip array with eight associated receivers and ahigh speed, high accuracy multi-channel analog to digital interface connecting thereceivers to the TMS320C30, a high speed digital signal processor.Development of the fully functional system proceeded in three stages. Firstly thedesign, construction and testing of the experimental array. Secondly the implementationand assessment of efficient algorithms to realise real-time digital beamcontrol in a hostileenvironment. Finally the testing and further development of the operating system in acontrolled environment.Initial results confirmed that full digital beamcontrol of the array's pattern waspossible with source search and tracking functions performed in a hostile environment inreal-time. However the pattern quality was degraded due to errors in the antennas feedsand multi-receiver mismatch. Using low-level digital calibrations these errors, as well asmutual coupling and near-field errors, were accurately estimated and compensatedresulting in near-optimal pattern control.The work here demonstrated the extended capabilities and potential advantagesthat are achievable through the use of advanced digital array signal processing. Thefeasibility of the system was dependent on the use of efficient algorithms that wouldminimise the signal processing load. Presently the techniques are applicable tonarrowband surveillance and communication systems such as over-the-horizon radar andmobile satellite services, where the processing requirements are moderate. Howeverfuture applications will progress to wider band systems as VLSI technology developsmultiplying digital processing power