An L-band direct-sampling digital radiometer: design and performance evaluation

This paper examines the noise characteristics of a direct RF sampling receiver whose architecture is suitable for high resolution aperture synthesis radiometry. The authrs have designed a 1.4 GHz direct-sampling digital radiometer (DSDR) to verify the discrete-time statistical model of the receiver and to evaluate current analog-to-digital converter technology. Several tests characterize the dynamic range and noise-equivalent sensitivity (NE/spl Delta/T) caused by quantization, finite data sampling, and variations in signal bias. The results of a benchmark case study suggest that, with DSDR configured in a total power mode, a sensitivity of 0.2 K is attainable for Earth remote sensing applications like soil moisture retrieval.