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A 32GHz bandwidth VLBI capable correlator and phased array has been designed and deployed^a at the Smithsonian Astrophysical Observatory’s Submillimeter Array (SMA). The SMA Wideband Astronomical ROACH2 Machine (SWARM) integrates two instruments: a correlator with 140kHz spectral resolution across its full 32GHz band, used for connected interferometric observations, and a phased array summer used when the SMA participates as a station in the Event Horizon Telescope (EHT) very long baseline interferometry (VLBI) array. For each SWARM quadrant, Reconfigurable Open Architecture Computing Hardware (ROACH2) units shared under open-source from the Collaboration for Astronomy Signal Processing and Electronics Research (CASPER) are equipped with a pair of ultra-fast analog-to-digital converters (ADCs), a field programmable gate array (FPGA) processor, and eight 10 Gigabit Ethernet (GbE) ports. A VLBI data recorder interface designated the SWARM digital back end, or SDBE, is implemented with a ninth ROACH2 per quadrant, feeding four Mark6 VLBI recorders with an aggregate recording rate of 64 Gbps. This paper describes the design and implementation of SWARM, as well as its deployment at SMA with reference to verification and science data.

A series of direct numerical simulations (DNS) were conducted of turbulent jets issuing from acoustically lined pipe. The inclusion of the pipe in the simulations with a fully turbulent flow inside ensures that all possible noise generation mechanisms are represented. Earlier results from a similar pipe/jet configuration, albeit without acoustic liner treatment, showed contamination of the far field noise field by interior noise from the pipe. Therefore, here two key modifications were made. Firstly, the interior pipe walls were acoustically lined using an impedance condition. Secondly, the turbulent pipe inflow boundary condition was modified to reduce spurious noise introduced into the axisymmetric mode. The sound radiation from the pipe/jet configuration was analysed using a phased array source breakdown technique. It is demonstrated that the modification of the inflow boundary results in a strongly reduced contribution of the interior noise component to the farfield noise in the axisymmetric mode, while the acoustic liner is effective in reducing the interior noise contribution to farfield noise in the higher azimuthal modes. This enables the source breakdown analysis to extract the jet mixing noise contributions to the farfield much more clearly.