SPECIAL FEATURE
Disruptive Technologies for COTS Products:
Software Defined Radio (SDR) Trends Over the Last Year By Brandon Malatest, Founder - PerVices Trends in the software defined radio (SDR) market over the last 12 months have been centered around increasing performance while simultaneously navigating through challenges brought on by the COVID-19 pandemic. While a lot of capabilities in SDRs stem from advances in commercial-off-the-shelf (COTS) technologies enabling these advanced platforms, issues related to supply chain shortages for semiconductors have been particularly troubling. This article discusses the types of COTS RF components, field-programmable gate array (FPGA) technologies, as well as capture, storage and playback solutions that had been driving the SDR industry forward over the past year. Alongside this, it discusses the unique challenges faced in the design and development of SDRs due to the global shortage of semiconductor based technologies. SDR Technology Trends Over the Last 12 Months Extended capabilities for a variety of industry applications have been brought on by advances in SDRs with integrated COTS technologies. For starters, releases of convertor devices with higher sampling rates and bandwidths lead to higher instantaneous bandwidth SDRs. Instantaneous bandwidth generally refers to what is available at the output of the analog-to-digital convertor (ADC). This is for complex IQ (in-phase and quadrature component) pairs of data, most often used in SDR, and corresponds to the sample rate of the ADC (whereas for real RF signals, this is one-half the sample rate, by Nyquist’s theorem). As well, increases in digital throughput (rate of data flowing to/from SDR from/to host system) has been important for passing this huge amount of data to a host system for processing. Combining both features in a one 16
COTS Journal | December 2021
package solution has also been a trend in the industry. Such products that offer the highest performance radio front end capabilities, as well as processing and storage capabilities. This instantaneous bandwidth and increased data throughput is crucial for spectrum monitoring due to this application requiring capture of a very wide bandwidth of the spectrum almost instantaneously, for such tasks as ensuring clear communication channels, monitoring restricted areas for interference, and so on. Similarly for electronic warfare (EW) systems, the need to identify and counter threats, including surveillance and/or tracking radars, is critical to mission success. EW relies on detecting these threats over a wide capture bandwidth near instantaneously and providing counter measures. Technologies enabling these capabilities have included new gigasample per second (GSPS) high speed convertors, high performance FPGAs and IP cores, as well as ultra high speed optical transceivers (qSFP+ 100G links) and their associated PCIe-based NICs.
Figure 1: NI Ettus X410 SDR
JESD204B interface based ADC/DACs are particularly crucial for enabling these wider bandwidths, as they allow for synchronizing multiple ADCs and the FPGA, thus increasing instantaneous bandwidth. Such advances in wide-bandwidth capturing and monitoring systems would not be possible without this interface. FPGA with RFSoC technology has also been an important trend. For instance, the Xilinx Zynq UltraScale+ FPGA and Intel Stratix FPGA both offer high-throughput digital signal processing (DSP) and IP cores for highly parallel tasks like onboard forward error correction (FEC), JESD204 implementation, and digital up/down conversion (DUC/DDC). Integrating the latest Ethernet technology IP cores into FPGAs has also been crucial for packetizing such high amounts of data for sending over qSFP+ transceiver ports, which enable the lowest latency SDRs. The latest high-end SDR products have taken advantage of these COTS technologies. In terms of instantaneous bandwidth, the Pentek
