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NCSA NEWS |
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Giving Sensors an EdgeNCSA pairs sensors with software-defined radio
The ESP/SDR project was undertaken last year as part of the National Center for Advanced Secure Systems Research (NCASSR), which is funded by the Office of Naval Research. The ultimate goal is to develop a single, tiny integrated circuit that contains both sensors and a software-defined radio—one in which the radio's waveform is programmed by software, rather than determined by hardware, which results in an extremely flexible, multi-band, multi-mode radio. Tiny sensors equipped with SDR could be released to gather data for climate research. Or they could monitor pollution in the atmosphere. Or they could be attached to animals to gain insight into their environment, habits, and health. Far from home base, each sensor would configure its SDR as a global positioning satellite receiver in order to pinpoint its location. Then the sensor could check on the available radio receivers in its area, configuring its SDR to function as a cellular telephone if there is a tower nearby or to become an amateur packet radio if there is a helpful operator in the neighborhood. The sensor would be able to tune itself to match whichever radio receivers/transmitters were available in the area, and could then send its data back to a central repository, where it could be compiled and analyzed. The SDR prototype represents a preliminary but significant step toward that goal. How does a radio work?Radio technology is ubiquitous. We're surrounded by clock radios, car radios, cellular phones, GPS, television, wireless Internet access, radio-controlled toys, garage door openers, police radios, satellite communications, and other devices that rely on radio waves to transmit data. All of these diverse forms of communication rely on electromagnetic radio waves to carry information, with different forms of radio communication using different wave frequencies. A generic radio communication follows the following steps:
In a standard radio, all of these functions—modulation, transmission, reception, demodulation, and amplification—are performed by hardware. Existing technologies for voice, video, and data use different data types and signal processing techniques. And because these differences are locked in hardware, they're impossible to bridge. The radio in your car can't suddenly transform into a cell phone, even though it might be convenient. The SDR advantageThe goal of software-defined radio is to transfer signal-processing functions from rigid hardware to flexible software. Then a single device can actually contain many modes of communication and can switch between them just by adjusting its software. If the only thing defining your cellular phone is its software, then the device could also contain the software to be a ham radio and could switch gears when needed. One often cited application for SDR would be enabling various branches of the military—which have different communications systems to suit their varying needs—to easily communicate with one another. There are already some available commercial SDRs, but they are expensive, so NCSA's team set out to develop a lower-cost alternative that can be used by the research community for experimentation and development. NCSA's project is also unique because it focuses on the merging sensors with SDR for the transmission of data rather than on voice applications. The NCSA team started with off-the-shelf hardware, freely available hardware designs, and GNU Radio, an open-source toolkit for digital signal processing. GNU Radio provides a collection of software that can be combined with minimal hardware to create devices in which the radio waves are defined by software rather than hardware. The radio prototype developed at NCSA expanded upon the receive-only capabilities of the GNU Radio. The NCSA SDR can both transmit and receive in the 902-928 MHz Industrial-Scientific-Medical (ISM) band (steering clear of the frequency bands reserved by the Federal Communications Commission for AM and FM radio, television, cellular phones, etc.). NCSA's SDR prototype—which measure approximately 5 inches long, 2.25 inches wide, and about an inch high—consists of:
The prototype can encode a signal and send it out, and it can receive a signal and decode it. All of the plans for NCSA's prototype are open source and are available for free to other developers. Plans can be found online at http://www.ncassr.org/projects/sdr/. Now that NCSA has developed a basic device that can receive and transmit data, the next challenges will be:
For More Information:
Team Members: Access Online | Posted 9-21-2004 |
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