Glancing Through Massive Binary Radio Lenses: Hardware-Aware Interferometry With 1-Bit Sensors

Abstract

Energy consumption and hardware cost of signal digitization together with the management of the resulting data volume form serious issues for high-rate measurement systems with multiple sensors. Switching to binary sensing front-ends results in a resource-efficient layout but is commonly associated with significant distortion due to the nonlinear signal acquisition. In particular, for applications that require to solve high-resolution processing tasks under extreme conditions, it is a widely held belief that low-complexity 1-bit analog-to-digital conversion leads to unacceptable performance degradation. In the Big Science context of low-frequency radio astronomy, we propose a telescope architecture based on simplistic binary sampling, precise probabilistic modeling, and likelihood-oriented data processing. The main principles, building blocks, and advantages of such a radio telescope system, which we refer to as The Massive Binary Radio Lenses, are sketched. The open engineering science questions which have to be answered before building a prototype are outlined. We set sail for the academic technology study by deriving a statistical algorithm for interferometric imaging from binary array measurements. The method aims at extracting the full discriminative information about the spatial power distribution embedded in a binary sensor data stream without bias. Radio measurements obtained with LOFAR are used to test the developed imaging technique and discuss visual and quantitative results. These assessments shed light on the fact that binary radio telescopes are suited for surveying the universe.

A 1 bit Raw Voltage-recording System for Dedicated Observations of Transients at Low Radio Frequencies

“…Our results indicate that in such circumstances the sensitivity to observe faint events within a short time interval depends largely on the effective collecting area and the observing bandwidth. It is well known that absolute flux measurements can be difficult in 1 bit receivers (Van Vleck & Middleton 1966;Udaya Shankar & Ravi Shankar 1990;Ramkumar et al 1994;Ramesh et al 2006;Stein 2019). But in a wide-field multibeam system where the primary requirement is to cover the maximum area of the sky with high temporal and spectral resolution, such binary receiver systems can be beneficial.…”