Design and implementation of the MIRAS digital correlator

The MIRAS imaging radiometer includes a digital one-bit correlator array. The configuration of a future MIRAS flight model features more than 100 antenna elements. This requires a correlator array with more than 10 thousand correlators. The feasibility of MIRAS is demonstrated by a breadboard with 11 complex channels and 110 correlators. The sampling frequency is 50 MHz and the integration time is 285 msec. The described demonstrator uses high speed comparators for analog-to-digital conversion and field-programmable gate arrays (FPGAs) for digital processing. The tests using a specific testbed have shown the difficulty of stimulating the correlators for the purpose of precise calibration. The described correlator has been developed for the European Space Agency