Distributed sensing via the ensemble spectra of uncoupled electronic chaotic oscillators

An electronic chaos generator involving cross-coupled inverter rings with lengths equal to the smallest odd prime numbers is considered, and a spatiotemporally-varying control parameter, hypothetically corresponding to a physical variable to be sensed, is introduced akin to a baseband signal. It is shown that, owing to the fine-grained structure of the spectrogram conveniently generated by this circuit, the control parameter setting and its fluctuations can be accurately estimated from the frequency spectrum, or a portion of it, for instance using a small neural network. Mimicking the effect of a passive receiver listening to a set of such nodes, the effect of summing the partially spectrally-overlapping and largely incoherent signals arising from multiple unsynchronized transmitters is then considered. The possibility of estimating some features of the statistical and topographical distribution of the control parameter from the frequency spectrum of the population ensemble signal(s) is indicated. Physical feasibility is corroborated by experiments involving an integrated circuit prototype realized using 65 nm CMOS technology, through which measurement reproducibility is also assessed. The proposed approach may have advantages for realizing distributed sensing applications because synchronization among the sensor nodes is not required, allowing the use of considerably simpler transmitters rather than mutually-coupled oscillators.