By Duncan Bosworth // Nov. 29, 2013
Following the general release of Analog Devices' AD9361 configurable-radio front-end chip in October 2013, the company's Duncan Bosworth adds some detail on the IC and on the background to applications in which it may be used; the highly integrated, mixed-signal RF IC makes, he says, broadband SDR designs smaller, lighter, and less power hungry.
The proliferation of different, incompatible radios is a serious problem in military and aerospace situations, where a team may need units for airborne links, satellite communications, a base relay station, and an emergency transmitter, as well as application-specific roles such as for UAV operation. Each of these radio links serves a vital purpose, and leaving one out of the mix would deprive the operational team of a needed resource. Yet each radio carries a cost in size, weight, and spare battery needs. The problem is further complicated as new requirements and links are added to the list.
The solution is obvious, at least “on paper”: a universal full-duplex radio module which can be used across all platforms and dynamically reconfigured in the field as needed. The “one-radio” goal would lessen the load, provide flexibility and versatility, be efficient and so provide longer operating life from a single set of batteries, and thus provide significant SWaP (size, weight, power) advantages. That was the underlying premise of programs such as the JTRS (Joint Tactical Radio System) and software-defined radio (SDR) efforts.
But making the universal radio concept into a reality has proven harder than envisioned. While Moore's law has driven the availability of the high-performance, lower-power processors (including implementations on FPGAs) which are needed, providing the suitable integrated analogue front end (AFE) has been much more difficult. The demands on this functional block – which resides between the antenna and the processor and is the interface between the real-signal world and the digital world – are complex, varied, and stringent.