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This paper discusses the utilization of a relatively inexpensive wideband radio receiver in combination with a digital down-converter (DDC) based data recorder to capture and record real world radio signals. The resulting in-phase (I) and quadrature (Q) data files are then imported into MATLAB for processing. This batch processing of real world radio signals allows for a tremendous amount of classroom...
The neural network method of detection for FSK signals is presented. The application of constructed system to detection of MSK signals is considered. Processing of test signals by the proposed method shows its capacity for work.
A stochastic differential equation for describing the dynamics of a scattered electric field at a moving receiver for a wireless channel is derived. The derivation is based on an extension of Jakes' model where the Doppler shifts are described as usual but where the phases are time-varying and described by Wiener processes. An approximation to this stochastic differential equation that is easier to...
Rateless codes for erasure channels were recently proposed by Luby with very efficient coding and decoding schemes. However, designing an efficient decoding rateless code for binary error channel (BEC), still remains a difficult problem. In this work we propose a rateless decoding algorithm for the BEC using a coding matrix G with a high level of sparsity. The distribution used to generate the elements...
In this contribution, a particle filter (PF) is proposed for tracking a single target illuminated with a digital-video-broadcasting terrestrial (DVB-T) signal in a multistatic radar system. This algorithm utilizes a single-stage scheme, i.e. it estimates the target position trajectory in a Cartesian coordinate system directly from the signal reflected by this target. The multiple stages adopted in...
Detection and resolution are the two fundamental tasks to be performed by a sonar system deployed in a multi-target environment. A matched filter is the optimum detector for a known signal in white noise and an inverse filter achieves the optimal resolution when the received signal-to-noise ratio (SNR) is very high. The main-lobe width of the autocorrelation function (ACF) of the transmitted signal...
Motivated by the echo-location system of a bat, I described the idea of cognitive radar in 2006 for the first time. This paper expands on this novel idea. In particular, the paper focuses on a cognitive tracking radar, the implementation of which comprises two distinct functional blocks, one in the receiver and the other in transmitter with a feedback link from the receiver to the transmitter. To...
Multipath signal propagation is the defining characteristic of terrestrial wireless channels. Virtually all existing statistical models for wireless channels are implicitly based on the assumption of rich multipath, which can be traced back to the seminal works of Bello and Kennedy on the wide-sense stationary uncorrelated scattering model, and more recently to the i.i.d. model for multi-antenna channels...
This paper introduces a line-of-sight (LOS) and non-LOS (NLOS) separation technique based on the statistics of the phase difference of two received signals. The phase difference is achieved via a co-installed synchronized two-receiver system. The variance of the phase difference is used to separate LOS and NLOS. The probability-density-function (PDF) of the received signal phase generated by NLOS...
Dynamic spectrum access (DSA) technology can improve the spectrum utilization significantly and is the key solution to the spectrum scarcity problem. In a typical DSA scenario, the secondary user (SU) is required to co-exist with the primary user (PU) in a non-interfering manner. However, the SU's spectrum sensing limitations can result in erroneous secondary transmissions that can affect the PU's...
This paper focuses on the channel estimation and symbol detection problems in multi-input multi-output (MIMO) underwater acoustic (UWA) communications. To enhance channel estimation performance, a cyclic approach for designing training sequences and an iterative adaptive approach (IAA) for estimating the channel taps are presented. Sparse channel estimates can be obtained. by combining IAA with the...
Radio Interferometry is an essential method for astronomical observations. Self-calibration techniques have increased the quality of the radio astronomical observations (and hence the science) by orders of magnitude. Recently, there is a drive towards sensor arrays built using inexpensive hardware and distributed over a wide area acting as radio interferometers. Calibration of such arrays poses new...
In this paper, we study the performance of orthogonal frequency division multiplexing (OFDM) over underwater acoustic multipath channels with different Doppler scales on different paths. We first derive an exact inter-carrier-interference (ICI) expression after incorporating the compensation of nonuniform Doppler shifts across OFDM sub-carriers. Based on the assumption that the residual ICI is dominantly...
Data rate and reliability are two critical figures of merit in communication systems, especially in underwater acoustic channels with limited bandwidth and double selectivity. In this paper, we will present our recent results of four rate- or reliability-oriented underwater acoustic communication schemes. We will show that the rate-oriented basis expansion model (BEM)-based single-carrier scheme provides...
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