The MCSA 2.1: A fully digital real-time spectrum analyzer developed for NASA's SETI Project

Abstract

The MCSA 2.1, the Multi-Channel Spectrum Analyzer, is a fully digital spectrometer optimized for the detection of narrow-band signals. The MCSA 2.1 has a single analog input, which is fed to an analog-to-digital (A/D) converter running at 130 M samples per second, and hence covers a 65 MHz bandwidth. The MCSA 2.1 design includes a digital downconverter, which bandpasses 10 MHz, downshifts it to baseband, and outputs complex samples at 10.833 MHz. This 10 MHz “superband” is split into 144 “bands” of 69.4 kHz, then further split into 108 “subbands” of 643 Hz, then divided into “bins” of six simultaneous resolutions: 1, 2, 4, 7, 14, and 28 Hz. The data from each resolution is normalized by the estimated noise power and then output as: (1) 4-bit power for incoherent Continuous Wave (CW) detection; (2) 8-bit thresholded power for pulsed signal detection; and (3) 32-bit complex amplitude for almost non-drifting coherent CW detection and for possible future signal detectors. The MCSA 2.2 has two inputs, exactly twice the hardware, and processes two antenna polarizations which are available at radioastronomy observatories. The MSCA 2.2 includes 70 Printed Circuit Boards (PCB), including 10 custom logic board designs and two buffer board designs. The system is under development for NASA's Search for Extra-Terrestrial Intelligence (SETI) Project. Provided adequate NASA funding is available, the MCSA 2.2 will be installed and performing SETI searches in October 1992.