The S2 VLBI Correlator: A Correlator for Space VLBI and Geodetic Signal Processing

We describe the design of a correlator system for ground and space-based VLBI. The correlator contains unique signal processing functions: flexible LO frequency switching for bandwidth synthesis; 1 ms dump intervals, multi-rate digital signal-processing techniques to allow correlation of signals at different sample rates; and a digital filter for very high resolution cross-power spectra. It also includes autocorrelation, tone extraction, pulsar gating, signal-statistics accumulation.Comment: 44 pages, 13 figure

Onboard utilization of ground control points for image correction. Volume 1: Executive summary

Operation of a navigation system, centered around image correction, was simulated and the system performance was analyzed. Onboard utilization of ground control points for image correction is summarized. Simulation results, and recommendations for future mission requirements are presented

Pipelined digital SAR azimuth correlator using hybrid FFT-transversal filter

A synthetic aperture radar system (SAR) having a range correlator is provided with a hybrid azimuth correlator which utilizes a block-pipe-lined fast Fourier transform (FFT). The correlator has a predetermined FFT transform size with delay elements for delaying SAR range correlated data so as to embed in the Fourier transform operation a corner-turning function as the range correlated SAR data is converted from the time domain to a frequency domain. The azimuth correlator is comprised of a transversal filter to receive the SAR data in the frequency domain, a generator for range migration compensation and azimuth reference functions, and an azimuth reference multiplier for correlation of the SAR data. Following the transversal filter is a block-pipelined inverse FFT used to restore azimuth correlated data in the frequency domain to the time domain for imaging

The Miniaturization of the AFIT Random Noise Radar

Advances in technology and signal processing techniques have opened the door to using an UWB random noise waveform for radar imaging. This unique, low probability of intercept waveform has piqued the interest of the U.S. DoD as well as law enforcement and intelligence agencies alike. While AFIT\u27s noise radar has made significant progress, the current architecture needs to be redesigned to meet the space constraints and power limitations of an aerial platform. This research effort is AFIT\u27s first attempt at RNR miniaturization and centers on two primary objectives: 1) identifying a signal processor that is compact, energy efficient, and capable of performing the demanding signal processing routines and 2) developing a high-speed correlation algorithm that is suited for the target hardware. A correlation routine was chosen as the design goal because of its importance to the noise radar\u27s ability to estimate the presence of a return signal. Furthermore, it is a computationally intensive process that was used to determine the feasibility of the processing component. To determine the performance of the proposed algorithm, results from simulation and experiments involving representative hardware were compared to the current system. Post-implementation reports of the FPGA-based correlator indicated zero timing failures, less than a Watt of power consumption, and a 44% utilization of the Virtex-5\u27s logic resources

Flow-Velocity Measurement for Bulk Granular Solids in Pneumatic Conveyor Pipes Using Random-Data Correlator Architecture

Abstract-This paper discusses a correlative-measurement technique for the evaluation of the flow velocity of bulk granular solids moving through the pneumatic conveyor pipes in both the dense and dilute phases. Flow velocities are recovered from the cross-correlation functions between the pairs of signals produced by the noninvasive capacitive sensors placed in circular layers at a given distance on the conveyor pipe. A random-data correlator architecture is discussed as a cost-effective solution for the real-time computation of the multiple correlation functions used for the estimation of the cross-sectional tomographic model of the flow-velocity profile in the dilute phase. Index Terms-Dense phase, dilute phase, particle flow velocity, pneumatic transport of bulk granular solids, random-data correlator architecture

Advanced digital SAR processing study

A highly programmable, land based, real time synthetic aperture radar (SAR) processor requiring a processed pixel rate of 2.75 MHz or more in a four look system was designed. Variations in range and azimuth compression, number of looks, range swath, range migration and SR mode were specified. Alternative range and azimuth processing algorithms were examined in conjunction with projected integrated circuit, digital architecture, and software technologies. The advaced digital SAR processor (ADSP) employs an FFT convolver algorithm for both range and azimuth processing in a parallel architecture configuration. Algorithm performace comparisons, design system design, implementation tradeoffs and the results of a supporting survey of integrated circuit and digital architecture technologies are reported. Cost tradeoffs and projections with alternate implementation plans are presented