In the last ten years, many approaches have been proposed to address automatic target detection (ATD) in hyperspectral sensor imagery (HSI). Conspicuously missing from that list is a relatively unknown approach to time series analysis, called higher order zero-crossings (HOC). In this paper, we investigate HOC sequences and their application to target detection in HSI. HOC sequences are based on a surprisingly fruitful connection between bank filtering and signal zero-crossings. They are generated from the application of a bank of filters to a finite signal or time series having zero mean. The application of each filter from the bank changes the signal oscillation pattern and alters the zero-crossing count. Accordingly, the application of each member filter gives rise to a zero-crossing count. We consider the oscillation pattern changes, or variations thereof, as a function of frequency modulation (FM) that may be intrinsic to hyperspectral signatures and that apparently has never been exploited in the target community. Investigating FM functions in signatures triggered a natural behavior to investigate the existence of intrinsic AM (amplitude modulation) as well. Preliminary results indicate that intrinsic AM-FM characteristics of objects' hyperspectral signatures may be useful for target detection.