The concept of a software or “cognitive” radio has been around for about 20 years, and has progressed to the point where open-source software code is available. A cognitive radio is “smart” in the sense that it is continuously aware of changes in radio frequency (RF) spectrum and can decide which frequency and power choices are best at a particular time.
The problem has not been the concept or the radio’s baseband processing, but rather, the RF front-end technology. Receivers and transmitters based on conventional analog technology have struggled to provide the full-spectrum performance needed for a true cognitive radio. The RF front end of an intelligent, flexible radio must be reprogrammable — on the fly, just as the baseband processors — to operate over a very wide swath of spectrum and a multitude of wireless standards, protocols, and waveforms.
Hypres of Elmsford, NY, is developing a superconductor-based, all-digital RF transceiver that can help pave the way to intelligent radio design. Marketed under its Digital-RF™ product line, Hypres is developing a line of reprogrammable, all-digital receivers and transmitters through a variety of government and commercial contracts. The Digital-RF product line includes versions for satellite and tactical communications, signal intelligence, electronic warfare, and RADAR.
Hypres has been developing the Digital-RF transceiver program for the Missile Defense Agency (MDA) and other government services in collaboration with research institutions such as the University of Rochester. The company recently built and delivered four prototype units, targeted toward various RF applications, to the U.S. Army, Navy, and Air Force. In partnership with SELEX Communications, Hypres is building a high-dynamic-range software radio receiver. When completed, this Digital-RF receiver will provide multichannel wideband reception with superior interference rejection and tolerance, which also is a necessary feature of cognitive radios.
Analog-to-Digital Conversion is Key
Key to the Digital-RF receiver is its analog-to-digital conversion technology that allows for wideband direct digitization at RF. Whereas conventional analog front ends require a series of components to down-convert the analog signal for the digitizer (before baseband signal processing), Digital-RF chips directly digitize the signal as it comes from the antenna. MDA funding has enabled development of the transmit side of the Digital-RF transceiver architecture, which features high-fidelity synthesis of broadband multi-carrier transmit waveforms without the distortion associated with analog components.
True all-digital systems will be critical in disaster scenarios in which responders are required to communicate with unfamiliar equipment and in environments with significant radio interference. All-digital radios will solve these problems and allow first responders to talk and listen simultaneously on any communications equipment, with the radio system automatically making any needed adjustments.
Much higher speeds are envisioned in the future and are being demonstrated on small-scale circuitry. For future applications, Hypres foresees the ability to demonstrate hundreds of gigabits-per-second chips and multichip modules for more complex systems that operate across multiple frequency bands, address a variety of standards, and offer greater flexibility to accommodate diverse modalities (e.g., voice, data, video, detection and ranging, and electronic countermeasures).
For more information, Click Here (Source: Joan Zimmermann/NTTC; MDA TechUpdate, Missile Defense Agency, National Technology Transfer Center Washington Operations)