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Whereas the legacy correlator utilizes a polyphase filterbank for the F-engine, the MWAX correlator employs the FFT, following the rationale presented in Appendix C. For the X-engine, development time/cost has been minimized by utilizing the existing open-source GPU correlator library “xGPU” (the same library at the heart of the legacy correlator). The standard xGPU library is used essentially unchanged for MWAX, with the exception of a small but crucial change to improve speed and reduce bus/memory traffic, found to be essential to making the design scalable to 256T and beyond. This modification is described in Appendix C.
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