Essential Limitations to Signal Detection and Estimation: An Application to the Arctic Under Ice Environmental Noise Problem

• Main Author: Dwyer,R F
• Other Authors: NAVAL UNDERWATER SYSTEMS CENTER NEW LONDON CT NEW LONDON LAB
• Format: Text
• Language: English
• Published: 1984
• Subjects: Snow; Ice and Permafrost; Acoustic Detection and Detectors; *ENVIRONMENTS; *ACOUSTIC DETECTION; *NOISE; *NARROWBAND; *UNDERICE; FREQUENCY; TIME INTERVALS; AUTOCORRELATION; ICE; SIGNALS; SOUND; INTERFERENCE; NAVAL RESEARCH; FAST FOURIER TRANSFORMS; STATISTICAL ANALYSIS; FUNCTIONS(MATHEMATICS); ARCTIC REGIONS; LPN-NUSC-A75030; Arctic; Arctic Ocean; Ice; permafrost
• Online Access: http://www.dtic.mil/docs/citations/ADA143828; http://oai.dtic.mil/oai/oai?&verb=getRecord&metadataPrefix=html&identifier=ADA143828

It has been observed that Arctic under ice noise is at times composed of narrowband components. The narrowband noise is primarily due to rubbing ice flows but possibly acoustic dispersion contributes to this phenomenon. This type of interference can significantly degrade the performance of systems which estimate autocorrelation functions to obtain bearing and range information. The data were collected as part of the 1980 Arctic Ocean experiments. Many segments of Arctic under ice data contained these highly dynamic narrowband components as shown in Figure 1. The statistical behavior of the dynamic narrowband frequency components were measured by first transforming the data into the frequency domain using a fast Fourier transform (FFT). Then the Kurtosis was estimated for each real and imaginary part of each frequency component over the band for a group of consecutive FFT segments. This procedure is called frequency domain Kurtosis (FDK) estimation. Thus, the FDK estimates the distribution over a time interval consisting of many FFT segments for each real and imaginary frequency component. Many of the Arctic data segments showed non-Gaussian components in the frequency domain based on the FDK estimate. This was due mainly to the highly dynamic nature of the narrowband ice components. Therefore, the FDK is a method whereby the desired signal can be distinguished from the unwanted ice sound. Presented at the International Conference on Acoustics, Speech, and Signal Processing, 19-21 Mar 84, San Diego, CA.