A Comparative Analysis of Spectral Linearity in the MeerKAT and MeerKAT Extension Receivers

This paper investigates the spectral linearity of the receiver systems in the MeerKAT and MeerKAT Extension radio telescopes.The investigation focuses on the ADCs, critical components in high-sensitivity receivers, and their importance in maintaining spectral fidelity.While previous work identified noise power as a factor influencing spectral nonlinearity, this study extends the analysis to compare two distinct receiver architectures.MeerKAT Extension's L-Band receiver employs an ADC with four cores, differential inputs, and a higher full-scale voltage than MeerKAT.Despite these design changes, linearity tests reveal similar spectral responses, suggesting that ADC non-linearity may be intrinsic to ADC devices rather than specific to a backend implementation.The investigation has implications for designing and using wideband receivers and digital backends.Future work will explore FFT shift schedules and raw ADC snapshots to characterise this phenomenon further.