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Vilnrotter, V.

Publications and source records attributed to Vilnrotter, V..

At least 37 records · Page 2
All sourcesNASA NTRSDOE OSTI
NASA NTRS2001

Avalanche Photodiode Arrays for Optical Communications Receivers

An avalanche photodiode (APD) array for ground-based optical communications receivers is investigated for the reception of optical signals through the turbulent atmosphere. Kolmogorov phase screen simulations are used to generate realistic spatial distributions of the received optical field. It is shown that use of an APD array for pulse-position modulation detection can improve performance by up to 4 dB over single APD detection in the presence of turbulence, but that photon-counting detector arrays yield even greater gains.

Srinivasan, M.↗
NASA NTRS2000

Adaptive Detector Arrays for Optical Communications Receivers

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 novel array detector concept reduces interference from background radiation by effectively assigning higher confidence levels at each instant of time to those detector elements that contain significant signal energy and suppressing those that do not. A simpler suboptimum structure that replaces the continuous weighting function of the optimal receiver by a hard decision on the selection of the signal detector elements also is described and evaluated. Approximations and bounds to the error probability are derived and compared with the exact calculations and receiver simulation results. It is shown that, for photon-counting receivers observing Poisson-distributed signals, performance improvements of approximately 5 dB can be obtained over conventional single-detector photon-counting receivers, when operating in high background environments.

Vilnrotter, V.↗
NASA NTRS1998

Optimum Receiver Structure for PPM Signals with Avalanche Photodiode Statistics

The maximum likelihood decision statistic for detection of pulse-position modulated signals with an avalanche photodiode is derived, using the more accurate Webb density rather than Poisson or Gaussian approximations for the distribution of avalanche photodiode output electrons. It is shown that for Webb-distributed output electtrons, the maximum likelihood rule is to choose the PPM word corresponding to the slot with the maximum electron count.

avalanche photodiode PPM Gaussian Poisson↗
NASA NTRS1997

A New Approach in Spacecraft Monitoring

This paper describes the end-to-end system design, operational scenarios, performance of the ground monitor, and the DS1 experiment.

on-board intelligence Beacon Monitor Europa Pluto↗
NASA NTRS1996

Channel capacity of an array system for Gaussian channels with applications to combining and noise cancellation

A closed-form expression for the capacity of an array of correlated Gaussian channels is derived. It is shown that when signal and noise are independent, the array of observables can be replaced with a single observable without diminishing the capacity of the array channel. Examples are provided to illustrate the dependence of channel capacity on noise correlation for two- and three-channel arrays.

Cheung, K. M.↗
NASA NTRS1996

Channel Capacity of an Array System for Gaussian Channels With Applications to Combining and Noise Cancellation

A closed-form expression for the capacity of an array of correlated Gaussian channels is derived. It is shown that when signal and noise are independent, the array of observables can be replaced with a single observable without diminishing the capacity of the array channel. Examples are provided to illustrate the dependence of channel capacity on noise correlation for two- and three-channel arrays.

Cheung, K.-M.↗