Mark E. Dunham

Reconfigurable Computer Array: The Bridge between High Speed Sensors and Low Speed Computing

A universal limitation of RF and imaging front-end sensors is that they easily produce data at a higher rate than any general-purpose computer can continuously handle. Therefore, Los Alamos National Laboratory has developed a custom Reconfigurable Computing Array board to support a large variety of processing applications including wideband RF signals, LIDAR and multi-dimensional imaging. The boards design exploits three key features to achieve its performance. First, there are large banks of fast memory dedicated to each reconfigurable processor and also shared between pairs of processors. Second, there are dedicated data paths between processors, and from a processor to flexible I/O interfaces. Third, the design provides the ability to link multiple boards into a serial and/or parallel structure.

Space-based FPGA radio receiver design, debug, and development of a radiation-tolerant computing system

Los Alamos has recently completed the latest in a series of Reconfigurable Software Radios, which incorporates several key innovations in both hardware design and algorithms. Due to our focus on satellite applications, each design must extract the best size, weight, and power performance possible from the ensemble of Commodity Off-the-Shelf (COTS) parts available at the time of design. A large component of our work lies in determining if a given part will survive in space and how it will fail under various space radiation conditions. Using two Xilinx Virtex 4 FPGAs, we have achieved 1 TeraOps/second signal processing on a 1920 Megabit/second datastream. This processing capability enables very advanced algorithms such as our wideband RF compression scheme to operate at the source, allowing bandwidth-constrained applications to deliver previously unattainable performance. This paper will discuss the design of the payload, making electronics survivable in the radiation of space, and techniques for debug.

Broad-band pulse performance of short helices

Helical antennas are popular and well characterized for CW frequency domain performance. Renewed interest in time-domain applications of electromagnetics, such as impulse radar, makes accurate time-domain data on broad-band antennas desirable. Although the principal endfire helix radiation mode has been extensively studied in the frequency domain, other modes important in pulse operation are poorly characterized, making a total Fourier transform approach difficult. We have performed impulse tests on helices with two to five turns, establishing novel features of the response and confirming some aspects of frequency domain data. Quick comparisons to time and frequency-domain modeling codes indicate good correspondence of gross features. Successful octave band-pulse operation was achieved, and a few features of helix pulse response invite further investigation. >

Efficiency and resolution of a new readout system for electro‐optical devices

Results of a new experiment investigating fiber‐coupled, astronomical CCD cameras as imaging systems for electro‐optic devices are described. These results indicate that single‐electron detection is achievable at 10‐kV energy and that the resolution can exceed 35‐μm FWHM. A system using such a camera to read a matched, high‐resolution phosphor is described, and characterizations of the various component efficiencies are given. It is concluded that this system offers formidable competition to microchannel plate intensified systems with respect to dynamic range, absolute sensitivity, and cost.

Modern circuit models for traveling-wave structures with nearest neighbor coupling

A method of analyzing traveling-wave structures based on a coupled-line physical model and a commercial frequency-domain microwave-circuit-modeling program is described. This approach provides significant insight into the sources of pulse distortion observed in real structures. The model is compared to a real structure to benchmark the models various components. >

High Efficiency Space-Based Software Radio Architectures: A Minimum Size, Weight, and Power TeraOps Processor

Los Alamos has recently completed the latest in a series of Reconfigurable Software Radios, which incorporates several key innovations in both hardware design and algorithms. Due to our focus on satellite applications, each design must extract the best size, weight, and power performance possible from the ensemble of Commodity Off-the-Shelf (COTS) parts available at the time of design. In this case we have achieved 1 TeraOps/second signal processing on a 1920 Megabit/second datastream, while using only 53 Watts mains power, 5.5 kg, and 3 liters. This processing capability enables very advanced algorithms such as our wideband RF compression scheme to operate remotely, allowing network bandwidth constrained applications to deliver previously unattainable performance.

Challenges and Successes in Space Based Reconfigurable Computing

For 6 years Los Alamos has developed space-compatible versions of Reconfigurable Computing (RCC). Several such designs are now operational. We describe the key research steps required to make commercial silicon processes amenable to Radiation Tolerant operations, and the limits on algorithms imposed by reliability concerns.

Advanced processing for high-bandwidth sensor systems

Compute performance and algorithm design are key problems of image processing and scientific computing in general. For example, imaging spectrometers are capable of producing data in hundreds of spectral bands with millions of pixels. These data sets show great promise for remote sensing applications, but require new and computationally intensive processing. The goal of the Deployable Adaptive Processing Systems (DAPS) project at Los Alamos National Laboratory is to develop advanced processing hardware and algorithms for high-bandwidth sensor applications. The project has produced electronics for processing multi- and hyper-spectral sensor data, as well as LIDAR data, while employing processing elements using a variety of technologies. The project team is currently working on reconfigurable computing technology and advanced feature extraction techniques, with an emphasis on their application to image and RF signal processing. This paper presents reconfigurable computing technology and advanced feature extraction algorithm work and their application to multi- and hyperspectral image processing. Related projects on genetic algorithms as applied to image processing will be introduced, as will the collaboration between the DAPS project and the DARPA Adaptive Computing Systems program. Further details are presented in other talks during this conference and in other conferences taking place during this symposium.

Saturation behavior of silicon Auston switches

The laser‐energized photoconductive switch (Auston switch) has been described previously with various applications. We report new measurements investigating the physical behavior of several types of silicon Auston switches, establishing basic quantum efficiency, charge‐voltage behavior, and voltage‐time response. Previously predicted nonlinear effects are observed, resulting in departures from ideal performance for most designs. However, operation in the saturated mode and a transmission line environment allows several designs to produce a step waveform that gives previously unattainable combinations of amplitude and rise time. In particular, the goal of a low aberration, 150‐V, 35‐ps step has been achieved, and process parameters affecting this performance are described.