A near-term replacement for the existing ALMA correlator using technology and signal processing developed for the SKA1 Mid telescope correlator/beamformer
We propose a low-risk, near-term replacement for the existing ALMA correlator, based on the technology and signal processing developed for the Square Kilometer Array, Phase-1 (SKA-1) Mid telescope correlator/beamformer (Mid.CBF). This replacement, the ALMA TALON Correlator (ATC), would provide significant improvements in ALMA science capability, encompass all ALMA antennas into one correlator, eliminate correlator sensitivity losses, and could be developed and delivered possibly as fast as 3 years from start of project, provided sufficient funding and priorities are in place. This is due to the use of most Mid.CBF signal processing blocks, with a key block inserted into the signal chain to facilitate doing so. Here we present the technology, physical architecture, signal processing architecture and correlator capabilities, and describe how such a replacement might fit within the existing ALMA physical and observing framework. As well as a direct existing-bandwidth replacement, double and quadruple bandwidth capability is possible with little to no additional engineering cost, and should fit within the existing correlator room. A future ALMA-2030 correlator could also build on this approach, using future technology, but likely without any fundamental architectural (and therefore observing model) changes.