Victor A. Vilnrotter

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In optical communication systems employing direct detection at the receiver, intensity modulations such as on–off keying (OOK) or pulse-position modulation (PPM) are commonly used to convey the information. Consider the possibility of applying space-time coding in such a scenario, using, for example, an Alamouti-type coding scheme [1]. Implicit in the(More)
The structure of an optimal adaptive array receiver for ground-based optical communications is described and its performance investigated. Kolmogorov phase screen simulations are used to model the sample functions of the focal-plane signal distribution due to turbulence and to generate realistic spatial distributions of the received optical field. This(More)
A modification of the traditional pulse-position modulation (PPM) scheme typically employed on the optical direct-detection channel is proposed that allows for significantly improved information throughput and bandwidth advantage. The scheme sends a multitude (K) of pulses per symbol interval and as such provides a signal constellation whose size, for a(More)
The use of radial basis function (RBF) networks and least squares algorithms for acquisition and fine tracking of NASA's 70-m-deep space network antennas is described and evaluated. We demonstrate that such a network, trained using the computationally efficient orthogonal least squares algorithm and working in conjunction with an array feed compensation(More)
This article develops the mathematical models needed to describe the key issues in using an array of antennas for receiving spacecraft signals for DSN applications. The detrimental effects of nearby interfering sources, such as other spacecraft transmissions or natural radio sources within the array’s field of view, on signal-to noise ratio (SNR) are(More)