This article details performance measurements vs. predictions of a 16-channel S-band direct sampling receiver design. The design is based on recently released direct sampling analog-to-digital converters (ADCs) clocked at 4 GSPS and sampling in the second Nyquist zone of the converter. The design configuration is first described with pointers to online references that provide further description. Next, the receiver is shown for both the RF components and the configuration of the embedded digital signal processing (DSP) that is now integrated into modern data converters. Calculations for single-channel performance predictions are presented and compared against measurements. With the single-channel performance understood, a set of measurements combining data from 16 channels evaluates the dynamic range improvements for noise density, spurious signals, and intermodulation products. The article concludes with a set of observations for the multichannel performance trends that can be used for extrapolation to models of large phased arrays implemented with many distributed receivers.
The next generation of MILCOM platforms will need to leverage more modern communication technologies that have been developed to enable commercial platforms such as cell phones and Wi-Fi.
This article compares the benefits and challenges of three common receiver architectures: a heterodyne receiver, a direct sampling receiver.
This article reviews the strengths and weaknesses of two electronic beamforming techniques: phase shifters (PSs) and true time delays (TTDs).