Field Programmable Gate Array Processor Research Articles

Integration of digital signal processing technologies with pulsed electron paramagnetic resonance imaging

The integration of modern data acquisition and digital signal processing (DSP) technologies with Fourier transform electron paramagnetic resonance (FT-EPR) imaging at radiofrequencies (RF) is described. The FT-EPR system operates at a Larmor frequency ( L f) of 300 MHz to facilitate in vivo studies. This relatively low frequency L f, in conjunction with our ∼10 MHz signal bandwidth, enables the use of direct free induction decay time-locked subsampling (TLSS). This particular technique provides advantages by eliminating the traditional analog intermediate frequency downconversion stage along with the corresponding noise sources. TLSS also results in manageable sample rates that facilitate the design of DSP-based data acquisition and image processing platforms. More specifically, we utilize a high-speed field programmable gate array (FPGA) and a DSP processor to perform advanced real-time signal and image processing. The migration to a DSP-based configuration offers the benefits of improved EPR system performance, as well as increased adaptability to various EPR system configurations (i.e., software configurable systems instead of hardware reconfigurations). The required modifications to the FT-EPR system design are described, with focus on the addition of DSP technologies including the application-specific hardware, software, and firmware developed for the FPGA and DSP processor. The first results of using real-time DSP technologies in conjunction with direct detection bandpass sampling to implement EPR imaging at RF frequencies are presented.

Radio Frequency Interference Mitigation at the Westerbork Synthesis Radio Telescope: Algorithms, Test Observations, and System Implementation

The sensitivity of radio astronomical stations is often limited by man-made radio frequency interference (RFI) due to a variety of terrestrial activities. An RFI mitigation subsystem (RFIMS) based on real-time digital signalprocessing is proposed here for the Westerbork Synthesis Radio Telescope based on a powerful field programmable gate array processor. In this system the radio astronomy signals polluted by RFI are "cleaned" with the RFIMS before routine back-end correlation processing takes place. The high temporal and frequency resolution of RFIMS allows the detection and excision of RFI better than do standard radio telescope back-end configurations.

FPGA-based military avionics computing circuits

There are processing requirements for military avionics applications in excess of 10/sup 10/ operations per second. Field programmable gate arrays (FPGAs) support these types of processing rates, and also offer other advantages (i.e., lower cost, lower power consumption, and smaller size) for military avionics relative to alternate types of processing solutions. This paper discusses the need for very high performance computing in military avionics, with precision guided munition (PGM) applications used as an example of this need. It presents a model suggesting continued rapid improvements in FPGA processing capability, and it analyzes the utility of FPGAs as processing engines in terms of processing capability, cost, power consumption, and size. It presents several examples of the use of FPGAs as processing engines which validate the model, and it also uses these examples to describe various FPGA-based processing engine implementation techniques.

Performance characterization of FPGA techniques for calibration and beamforming in smart antenna applications

A field-programmable gate array (FPGA) implementation is presented for a smart antenna application employing digital beamforming. The digital beamforming is performed at the RF signal carrier frequency by means of bandpass (IF) sampling, using high-speed 8-b analog-to-digital converters. The digital phased array receiver presented in this paper consists of an eight-channel system with back-end FPGAs for calibration and digital beamforming processing. The system operates in the L-band (1.8-2 GHz) with various bandwidths depending on the application and FPGA processing requirements. This paper focuses on two main topics, calibration methodologies and FPGA implementation for calibration and digital beamforming, and includes several performance trades. Results presented include real measured data that were collected with the system and processed via FPGAs.