A novel method to detect rising and setting tones

Abstract

Rising or setting tone is a natural phenomenon caused by the chorus emission, which has a discrete frequency time structure and increasing or decreasing frequencies. It usually happens in the Very Low Frequency (VLF) range and sounds like bird tweeting. Since the chorus emission seems to have a clue to space research for safe and secure satellite operations, there is a strong demand to detect such tweeting tone. To this end, we develop a new signal processing tool wherein the running spectra of a tone are first treated as the signals received with individual sensors in a linear senor-array. Then, the estimation of signal parameter via rotational invariance techniques (ESPRIT) algorithm is applied to estimate the rising or setting speed of the tone. In order to evaluate the proposed tool, we conduct simulations using chirp signals of different rising or setting speeds. The simulation results show that the rising or setting speed of a tone can accurately be estimated with the proposed tool.