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In this paper, we consider joint estimation of the Direction-of-arrival (DOA) and channel parameters of fully correlated sources impinging on a linear array sensors in Underwater multipath environment. Amindavar et al.[1] proposed a blind techniques for simultaneous estimation of the DOA and the channel parameters based on the assumption that the source signal can be modeled by a sum of weighted complex...
As a sonar transmitted waveform, binary phase-shift keyed (BPSK) signal has a nearly ideal ambiguity function. The good Doppler and time resolution properties make BPSK signal advantageous for underwater targets detection. Under the Doppler perturbation situation, the property of good Doppler resolution will result in a sharp decline in detection performance. In recent years, waveform fusion has got...
In this paper, an approach is presented to retrieve ionospheric total electron content (TEC) over oceans from Global Navigation Satellite System-Reflectometry (GNSS-R) delay-Doppler map (DDM). Here, an additional ionospheric delay (τI) is considered in the conventional DDM simulation process. Based on this, the least squares (LS) fitting method is employed for TEC retrieval by fitting the simulated...
In this paper, research was carried out to analyze the channel environment in the real sea using data measured in the shallow water of West sea of South Korea. By diversifying the distance between transmitter and receiver, we estimated RMS delay spread and maximum excess delay spread in various channel environments to draw coherence bandwidth and then estimated Doppler spread of received signal to...
In this study, performance verification of Resource spread FMT-OFDM system and FMT-OFDM system is carried out through a simulation in the underwater channel environment. The measurement was performed in the shallow water of Geojedo located in Namhae-gun, for the real sea channel modeling. We also analyzed the channel delay profile in different underwater channel environments by distance between transmitter...
This paper presents a single-hydrophone based method for source range localization from information contained in the multipath propagation in the reliable acoustic path (RAP) environment. The time delays between the direct (D) and the surface-reflected (SR) arrivals are obtained from the autocorrelation of the received signal and are compared with the D-SR time delays predicted by the acoustic model...
This paper introduces a new method which uses the consensus algorithm to solve the coordinate control problems of multi-AUVs. As the communication between the AUVs is difficult and easy to be interfered under the water, there must be time delay and data drop during the members communicate with each other. On the other hand, the math model of AUV is nonlinear and coupling, the feedback linearization...
This paper compares the performance of single pseudo-noise (PN) and dual PN (DPN) sequences for time of arrival (ToA) estimation in underwater acoustic (UWA) localization. The single PN scheme uses the correlation of a local PN sequence and the received PN signal to estimate the ToA. The DPN scheme utilizes the cross correlation of the two received PN segments in one signal frame to calculate the...
There are several sources of error affecting the accuracy of underwater ranging using acoustic signals. These errors have a direct impact in the performance of Long Baseline (LBL) navigation system. This paper presents the results of experiments designed to characterize the most significant sources of errors in acoustic ranging. For the experiments, we use a set of acoustic devices and compare distances...
In this work we describe our investigation into wideband channel models for the acoustic water pipe channel operating over the 10–50KHz frequency band. We provide experimental results for a straightforward water pipe system consisting of a single pipe of length 6.3m, diameter 7.1cm, constructed from PVC and terminated with water tanks at each end in a hydrostatic configuration. It is observed that...
In this paper, the methods for estimating and tracking sparse doubly spread channels in single-carrier coherent communications are investigated. The sparse doubly spread channel is parameterized by a few paths with different delays, Doppler scales, and gains. Based on the model, a low-complexity channel estimation algorithm is proposed. The channel estimation is divided into two stages, the first...
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