L.E. Estes

Naval Undersea Warfare Center, Newport, Rhode Island, United States

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Publications (10)5.13 Total impact

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    Preview · Article · Nov 2009
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    ABSTRACT: A method is described for modeling the effects of spatial apertures on optical sensor systems. The method consists of defining a set of basis functions that is obtained by partitioning the aperture image plane into a series of rectangular regions and replacing the field in each rectangular subregion with an orthogonal function series approximation. Each orthogonal function has a finite extent that is matched to the aperture image. The individual functions are propagated by application of the Fresnel approximation of the Rayleigh-Sommerfeld diffraction formula to other ranges, and the resultant functions are shown to be valid basis functions for defining a field at any other range. The technique is applied to a scattering problem using complex Fourier series.
    No preview · Article · Aug 2006 · Journal of the Optical Society of America A
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    ABSTRACT: The linear mechanism for optical-to-acoustic energy conversion is explored for optoacoustic communication from an in-air platform or surface vessel to a submerged vessel such as a submarine or unmanned undersea vehicle. The communication range that can be achieved is addressed. A number of conventional signals used in underwater acoustic telemetry applications are shown to be capable of being generated experimentally through the linear optoacoustic regime conversion process. These results are in agreement with simulation based on current theoretical models. A number of practical issues concerning linear optoacoustic communication are addressed that lead to a formulation of a linear-regime optoacoustic communication scheme. The use of oblique laser beam incidence at the air-water interface to obtain considerable in-air range from the laser source to the in-water receiver is addressed. Also, the effect of oblique incidence on in-water range is examined. Next, the optimum and suboptimum linear optoacoustic sound-generation techniques for selecting the optical wavelength and signaling frequency for optimizing in-water range are addressed and discussed. Optoacoustic communication techniques employing M-ary frequency shift keying and multifrequency shift keying are then compared with regard to communication parameters such as bandwidth, data rate, range coverage, and number of lasers employed.
    No preview · Article · Jul 2005 · Applied Optics
  • Lee E Estes · Gilbert Fain
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    ABSTRACT: Propagation through the ocean's surface at shallow angles with a laser has been successfully demonstrated experimentally in the ocean. A 6-mJ multipulse laser at a depth of 1.5 m in water with an attenuation coefficient of approximately 3.3 m(-1) was easily detected 600 m away on a sunlit day at an angle of 1 degree to the ocean's surface. The measured efficiency was 3.6 x 10(-2) (J/J)/sr (joules received per receiver steradian per joule transmitted). Statistical ray trace analysis and physical tank modeling produced equivalent efficiencies.
    No preview · Article · Aug 2002 · Applied Optics
  • L.E. Estes · G. Fain · J.D. Harris II
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    ABSTRACT: In order to predict the performance of in the water and through the surface laser communication systems, it is necessary to know the inherent optical properties of the water environment. In particular, knowledge of the absorption and scattering coefficients and the forward scattering phase function (FSPF) are required. Analytical models and photon Monte Carlo simulations can then make use of these inherent optical properties to predict system performance. In this paper the authors describe the design of a new device that can be used to conduct FSPF surveys. The device makes use of a green helium-neon laser operating at a 543.5 nanometer wavelength and thermoelectrically cooled CCD camera to make real time measurements. The system is powered from the deploying surface vessel and the data is recorded at each depth by a shipboard portable computer. In this manner vertical profiles of the FSPF can be obtained. The authors present some early results
    No preview · Conference Paper · Nov 1997
  • L.E. Estes · G. Fain · J.D. Harris II
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    ABSTRACT: The practicality of communication through the water's surface is explored using values from Buzzards Bay, Massachusetts. A series of measurements of absorption and attenuation as a function of frequency were taken in the bay. The resultant values were used to provide input to a numerical ray model of light propagating through the water column, a random surface and to a receiver in the air. Signal to noise ratios were calculated and show that an appropriately designed system is practical
    No preview · Conference Paper · Oct 1996
  • L.E. Estes · G. Fain · D. Carvalho
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    ABSTRACT: Describes a model useful for characterizing shallow water environments for evaluating communications concepts. Some comparisons between experiment and simulation for a variety of conditions are shown
    No preview · Conference Paper · Nov 1993
  • L.E. Estes · G. Fain · D. Carvalho
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    ABSTRACT: Not Available
    No preview · Conference Paper · Nov 1992
  • L.E. Estes · G. Fain · P. Caron
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    ABSTRACT: A wideband system (40 kHz-50 kHz) whose coding is self-synchronous and is adjustable for variations in coherence and reverberation times to obtain a maximum reliable data transmission rate for any given set of conditions is presented. To maximize data rate the approach takes full advantage of system bandwidth. At its simplest level a spectral line is used to represent a bit. The major delimiters of multispectral transmission (within a given system bandwidth) in this environment are coherence time due to Doppler spreading and reverberation time due to multiple transmission path. Banks of different frequencies are sequentially transmitted, each bank being reused after the reverberation time. Theory, experimental setup, and preliminary results are presented
    No preview · Conference Paper · Jul 1990
  • L.E. Estes · G. Fain
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    ABSTRACT: A progress report on a program to develop a low-cost GPS (Global Positioning System) receiver for marine applications is presented. The unit described is a highly digital, mostly one bit, software intensive receiver. The unit uses one RF mixer to baseband, a one-bit 2-MHz A/D (analog-to-digital converter), and five digital parallel signal processing channels. An AMLE (approximate maximum likelihood estimator) technique is used to acquire signals, and low dynamic loops are used for tracking. General principles guiding the design and a description of the receiver are given
    No preview · Conference Paper · Apr 1990

Publication Stats

25 Citations
5.13 Total Impact Points

Institutions

  • 1993-2006
    • Naval Undersea Warfare Center
      Newport, Rhode Island, United States
  • 1990-2002
    • University of Massachusetts Dartmouth
      • • Department of Electrical and Computer Engineering
      • • School for Marine Science and Technology
      New Bedford, Massachusetts, United States