Inner features of Spectra, that bit is classified, but Picdel has mentioned some stuff about it using alternate technologies. Basically, Spectra uses a superheterodyne receiver like a regular system, and lots and lots of correlators, similar to GPS. A Kalman filter is used for prediction, so it keeps the system within a particular bandwidth in relation to the signal that is being canceled. What really makes the difference is software, because the hardware itself isn't particularly revolutionary
“One of our programs at DARPA is taking a whole new approach to this problem, this is an effort we refer to as cognitive electronic warfare,” said DARPA director, Dr Arati Prabhakar. “We’re using artificial intelligence to learn in real-time what the adversaries’ radar is doing and then on-the-fly create a new jamming profile. That whole process of sensing, learning and adapting is going on continually.”
So this is what Spectra is basically doing.
The Russians have also deployed a similar system on the Richag-AV. But it does area jamming, meaning it jams the entire spectrum, anything that it doesn't recognize as what the Russian military uses, and it's all real time. This is also a digital GaN based system, similar to the upcoming Spectra upgrade.
