A Low Complexity Decimator for Communication between a Basestation and a Base Station Control System of an Underwater Acoustic Network

Abstract

Background/Objectives: We designed a decimator for a basestation-basestation controller communication of an underwater acoustic sensor network. Since it cannot be supplied with power smoothly, we focused on a low-complexity decimator.Method/Statistical Analysis: Many underwater acoustic communication systems including decimators have been implemented using a microprocessor because acoustic wave signals are typically processed at a lower operating frequency than operating frequency of microprocessors. However, we designed a specific hardware decimator that support a low-power underwater acoustic communication system based on specifications of Hoseo University research group to reduce power consumption. We used Matlab and Verilog-HDL to simulate our algorithm and architecture.Findings: Although a CIC filter has a simple and regular structure, it has a wide transition region and a narrow passband. So it is not suitable for underwater communication where channel spacing is narrow. We added a halfband filter for fast attenuation in the transition region and a compensation filter for passband attenuation compensation. We constructed the sampling rate conversion in three stages with an individual CIC filter. Since the last CIC filter was the most influential on the signal attenuation, the compensation filter was designed for the three-stage CIC filter. The halfband filter and the compensation filter were cascaded before and after the three-stage CIC filter, respectively, to reduce power consumption. Since the transition region of the halfband filter is located at the 1/4 frequency of the sampling frequency of the input signal, the sampling down rate of the three-stage CIC filter is half. Therefore, the proposed decimator has a narrow frequency transition region and a flat passband suitable for underwater acoustic communication.Improvements/Applications: Our proposed decimator makes it possible to realize a stable digital circuit in low frequency band signal processing such as sensor data processing as well as communication.