The September 2015 issue of Analog Dialogue contains…
The first of a four-part article series that explores a model-based design technique for wireless software-defined radio systems. This article tackles the complete system design: the RF signal chain, the digital processing, and the system software. The series, jointly written by ADI and two of our systems resource partners, Xilinx and MathWorks, presents a more holistic view of system design than what you might expect from Analog Devices, especially if you consider us just a component supplier. The authors will walk through the SDR system design process utilizing reference hardware and operating software, functional device models, and system code development tools. This design journey will demonstrate a working radio programmed to receive and decode automatic dependent surveillance broadcast (ADS-B) signals from commercial aircraft in the vicinity — and fully discerning the aircraft’s position, altitude, and velocity.
A second article on energy harvesting systems explores the technique of capturing and storing energy from a host of ambient sources such as solar, mechanical vibrations, temperature, movement, and RF signals. Energy harvesting technology has advanced such that now it’s feasible and economical to capture this “free” energy even though it contains very small quantities of power, and use it to perform periodic functions and supplement replace batteries in some electric equipment. This article looks at the block diagrams and design considerations involved with the highly efficient power regulators required for managing the periodic and varying energy levels of captured energy and converting it to stable and usable output power.
Contemplating these two articles brought to mind the crystal AM radios I had as a kid in the early 1960s. These sets could be considered the lowest form of radio receiver technology (outside of some folk’s alleged AM radio reception via loose tooth fillings). These simple radio circuits harvested their audio power by rectifying the modulation envelope of the received AM signal. I remember having a couple of sets resembling rocket ships and one fashioned as a Coca-Cola® vending machine. I’d venture to say that a fair number of us budding “radiomen” who were totally intrigued by these primitive radio receivers went on to become the design engineers who ultimately contributed to the development of software-defined radio technology.
Soon, SDR and energy harvesting will undoubtedly cross paths as the demands of The Internet of Things (IoT) will require self-powered networks and radio transceivers. So energy harvesting radios will once again rule, although software-defined, not cat whisker-defined. And they will likely not resemble Coke machines, but will most certainly be embedded in them.
Check out the September Analog Dialogue here.