The other day I found this short item in the ACM Tech News:
DARPA Pop-Up Testbed Takes On Spectrum Management
Government Computer News
George Leopold
April 7, 2017The U.S. Defense Advanced Research Projects Agency (DARPA) sponsored a recent event to test new modulation recognition strategies for navigating the radio frequency spectrum. The desired objectives included demonstrating new modulation recognition methods for identifying signal origins and types, and finding better techniques for sending and receiving information over the least trafficked spectral bands. “Modulation recognition is that first step towards getting beyond just describing ‘presence’ or ‘absence’ [and] actually describing what is present,” says Paul Tilghman with DARPA’s Microsystems Technology Office. The event employed about 30 modulation schemes, with hand-coded expert systems matched against newer machine-learning platforms. The former did better in identifying signal characteristics, but DARPA program manager Tom Rondeau expects the machine-learning method to catch up. DARPA says modulation recognition is vital for achieving “wireless situational awareness” that could help extract more capacity from congested electromagnetic spectrum, and then predict spectrum use and increase throughput.
After reading this, I said to myself, “How cool is this? what a great new use for artificial intelligence.” When I did a little Googling on the topic, though, I found out that modulation recognition has been around for at least 20 years. Now, I’m saying to myself, “How did I miss this?”
I’m not an AI expert, but it seems to me that whoever can crack this nut will be years ahead of the competition. Instead of setting up your radio for CW, SSB, or one of the digital, just let the radio do it. Instead of you or me extracting the information from a noisy signal, we’ll let the computer do it instead. And you know what, chances are the radio will do a lot better job than we can. The future’s going to look a lot more different than we can imagine.
Dave New, N8SBE says
Try searching for ‘cognitive radio’ and you’ll find a number of efforts in that area. The unfortunate downside is that congress keeps talking about asking the FCC to regulate public access to such technology, in an effort to provide security via obscurity. Broadcasters and wireless providers are worried that cognitive systems will be able to ‘crack’ their non-existent encryption schemes, thus enabling folks to steal their services. So, the knee-jerk reaction from the government is to attempt to legislate receivers, instead of requiring robust encryption/authentication schemes be fielded by suppliers.
Walter Underwood K6WRU says
Modulation recognition is a lot older than that. It is part of SIGINT (signal intelligence). You can learn a lot about a signal even if it is encrypted. The modulation, frequency, and timing tell a story. Location is pretty easy to do.
Let’s say we have identified a signal as the kind generated by the transmitters in enemy tanks. Then we look at the pattern of who is talking when, and identify the group commander. Check the exact frequency of each transmitter (differing by a few Hz, probably). Get the location of the commander’s transmitter, and give that to the artillery.