Thank you to Ramiro Utrilla Gutiérrez a PhD Candidate researcher at Universidad Politécnica de Madrid for writing in and sharing his research groups work on a low power SDR radio platform called "Migou". The basic idea is to combine software defined radio which is flexible but power hungry, with less flexible but power efficient hardware radios. The design files and BOM are creative commons licensed, and free to download. The radio is capable of operating in the 433 MHz, 868 MHz and 2.4 GHz bands at sample rates of up to 4 MSPS in SDR mode. Ramiro writes:
I'm the main developer of the MIGOU platform. This platform uses the Microchip AT86RF215 transceiver (like TinySDR and iotSDR) and a Microchip SmartFusion2 flash-based FPGA SoC.The particularity of our work is what we have called the hybrid radio approach, which proposes to provide low-resource devices with the ability to operate both as a current mote, using a hardware transceiver, and as an SDR system. This is possible using only the AT86RF215 transceiver. With these capabilities, hybrid radio end-devices can exploit the SDR hardware flexibility for those sporadic tasks that strictly require it, and still benefit from the energy efficiency of hardware transceivers for all other tasks.Our platform is not a commercial product, it is an open-source research tool. If you are interested, you can read more about our work in this article in Sensors journal, where we present the hybrid radio approach and the MIGOU platform, and in this article in IEEE Access journal, where we approach a Cognitive Radio problem from the perspective of our hybrid radio platform. Both articles are also open access.
The B105 Electronic Systems Lab also appear to have a website for the design which provides a summary:
MIGOU is a low-power wireless experimental platform designed to simultaneously address the energy-efficiency requirements of resource-constrained end-devices and the hardware flexibility demanded by the current Cognitive Radio (CR) and edge computing paradigms. This platform relies on the SmartFusion2 SoC that integrates an ARM Cortex-M3 processor and a flash-based FPGA, where high-speed processing tasks can be offloaded and computed more efficiently via hardware acceleration. In addition, at the radio level, the platform can operate both as a traditional node, which demands lower energy resources and development time, and as a Software-Defined Radio (SDR) system, which allows for the implementation of custom CR features. Moreover, the ability to dynamically switch between these two modes of operation opens the possibility for developing new hybrid strategies, taking advantage of both the flexibility offered by the SDR and the efficiency of the transceiver’s highly optimized baseband cores.
The power consumption of our platform was measured in transmit, receive, and sleep modes. These measurements were compared with the corresponding ones of other representative tools and systems: YetiMote, a traditional IoT end-device; MarmotE SDR, a low-power SDR system; and B200mini and B210 USRPs, two widely used high-performance SDR platforms. Moreover, all these devices were compared in terms of their hardware features. The results obtained confirmed that a state-of-the-art tradeoff between hardware flexibility and energy efficiency was achieved. These features will allow researchers to develop appropriate solutions to current end-devices’ challenges, and to test and evaluate them in real scenarios.