MAX2771 broadband SDR: impact of low bit resolution and application to passive radar measurements

The MAX2771 chip provides broadband (<44 MHz) signal processing and digitization in the lower (1.1-1.3 GHz) and upper (1.5-1.65 GHz) L-band. Initially dedicated to GNSS signal reception, two such chips clocked by a common frequency reference can be used for passive radar or direction of arrival measurements. In this presentation, we tackle the challenges of PLL setpoint drift leading to phase variations despite the common clock, the impact of low ADC resolution on the recorded signal characteristics, and on correlation calculation. These results are not confined to this particular chip, but valid for any low SNR recordings, including for radioastronomical measurement systems. We demonstrate the use of this setup on passive radar measurements using various ground based and spaceborne sources of opportunity.