We present real-time 3D image processing of flash ladar data using our recently developed GPU parallel processing
kernels. Our laboratory and airborne experiences with flash ladar focal planes have shown that per laser flash, typically
only a small fraction of the pixels on the focal plane array actually produce a meaningful range signal. Therefore, to
optimize overall data processing speed, the large quantity of uninformative data are filtered out and removed from the
data stream prior to the mathematically intensive point cloud transformation processing. This front-end pre-processing,
which largely consists of control flow instructions, is specific to the particular type of flash ladar focal plane array being
used and is performed by the computer's CPU. The valid signals along with their corresponding inertial and navigation
metadata are then transferred to a GPU device to perform range-correction, geo-location, and ortho-rectification on each
3D data point so that data from multiple frames can be properly tiled together either to create a wide-area map or to
reconstruct an object from multiple look angles. GPU parallel processing kernels were developed using OpenCL. Postprocessing
to perform fine registration between data frames via complex iterative steps also benefits greatly from this
type of high-performance computing. The performance improvements obtained using GPU processing to create
corrected 3D images and for frame-to-frame fine-registration are presented.
The problem of chromatic dispersion is well known and has long been a limiting effect in optical networks. The traditional solution for dealing with chromatic dispersion - dispersion compensating fiber - has a variety of drawbacks that limit its effectiveness in some 10 Gbps applications and in many 40 Gbps applications. Several new classes of tunable dispersion compensators have recently been developed to address these limitations. We will first review the causes and manifestations of chromatic dispersion and discuss the impact of residual chromatic dispersion, including its dependencies on transmission distance, bit rate, and data bandwidth. Then we will discuss the factors that create the need for tunability and examine how tunable dispersion compensators address these needs. Finally, we will review the technology behind currently available solutions for tunable chromatic dispersion compensation, including nonlinearly chirped fiber Bragg gratings, and contrast their advantages and disadvantages relative to the traditional solution of dispersion compensating fiber.
KEYWORDS: Signal processing, Fiber Bragg gratings, Filtering (signal processing), Control systems, Linear filtering, Digital signal processing, Optical filters, Servomechanisms, Modulators, Electronic filtering
Higher data capacity demands and lower interference requirements in the wireless communications arena are exploiting higher carrier frequencies and wider modulation bandwidths. Circuitry which can perform intermediate frequency processing over these more demanding ranges is needed to provide complex signal processing without commercial penalties. Photonics technologies utilizing Bragg Grating Signal Processing (BGSP) can bridge the gap between the very high frequency RF millimeter wave integrated circuit domains at the antenna interface and the CMOS digital signal processor sat the base band frequency interface. The desirable benefits of multiple; tap adaptive finite impulse response (FIR) and infinite impulse response filters and equalizers are well known; however, they are usually the province of digital signal processing and force the sample rates prior to these processors to a higher overall system power consumption level. BGSP provides these functions with discrete taps and digital controls but at the bandwidths usually reserved for RF circuitry because the actual processing occurs at optical frequencies and at wave lengths which are compatible with integrated circuit technologies. The high performance benefits of photonic processing can be realized if the stability control of the Bragg grating is derived from the same metric which induces in photonics its sensitivity to drift. We will present a orthogonally coded tap modulation technique which stabilizes the transfer function of the signal processor and enables significant adaptive IF signal processing to be obtained with very low size, weight, and power. Our demonstration of a photonic proof-of-concept architecture is a reconfigurable multiple tap FIR filter that is dynamically controlled to perform low pass, high pass, band pass, and band stop filters operating over bandwidths of 3 GHz.
KEYWORDS: Stars, Star sensors, Sensors, Signal to noise ratio, Device simulation, Monte Carlo methods, Data processing, Computer simulations, Telescopes, Navigation systems
A star sensor simulator was developed, which models the characteristics of the star, the background, the sensor's windows, the telescope, the detector, the electronics, and the environment, generating data which are similar to data received from a real star sensor. The simulated data are then processed to reveal the star sensing capability. The paper discusses the requirements of the star sensor simulator, the models used, and the simulator design and presents representative simulations.
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