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| ![]() Astronomical FFT processing system |
Overview
This is the old AstroFft1 system from 2002 that used FPGA's to perform the real-time FFT processing.Introduction
This document describes the Astro FFT processing system as designed and developed by Alpha Data Ltd and BEAM Ltd in conjunction with Bristol University. The purpose of the system is to process a 23 Mhz bandwidth signal and generate a power spectrum averaged over time. This allows a coherent signal spectrum to be brought out of a relatively large amount of noise.The system processes two separate analogue signals, normally two signal polarization's, with a 0 to 23 MHz bandwidth. The system then continuously, in real-time, performs a 4096 point FFT on each signal and averages the resultant power components over time. The resulting averaged power spectra are stored in data files that can be used for further data analysis.
System Hardware Overview
The system hardware consists of a dual Pentium processor based system housed in a 19 inch rack unit. The main FFT processing is performed by two Xilinx Virtex FPGA based PCI boards each of which has twin 14 bit analogue to digital convertors.System Software Overview
The system software is based upon the Linux operating system. This provides a full multitasking, networked operating system allowing access to the AstroFFT system from other systems on a local network. The system can either be run as a stand alone box on the network with no keyboard, mouse or display or as a fully fledged Linux workstation.The Astro FFT software itself, consists of two main applications: the AstroFft daemon and the AstroGui user interface.
Software Operation
The Linux system installed is RedHat 7.2. This is a full installation with all of the applications for a full Linux workstation and software development platform. This allows the system to be used as a full Linux workstation as well as a simple network resource.The Linux system has networking enabled and provides the following network resources:
- AstroFFT: The astro processing daemon. Remote applications can connect to this service to control the Astro FFT processing system.
- NFS: The NFS network file system protocol is supported allowing systems to access the /data directory on the system in read only mode.
- SMB: The SMB, Microsoft Windows network file system, protocol is supported allowing access to the /data directory with read only permissions as the astro user.
The AstroFft Daemon
This is the main control application of the Astro FFT processing system. This software process runs as a real-time process and is responsible for managing the FPGA hardware FFT engine, real-time post processing the FFT data, data storage and system control.It is controlled by commands sent over a network control socket from either the local AstroGui control process or a remote control process.
More information on the Astro FFT process is in the; AstroFft Software API .
The AstroGui User Interface
The AstroGui application provides a user with the means to control the data acquisition and logging parameters of the Astro FFT processing system. It connects to and controls the AstroFFT daemon. More information is in the AstroGui User Manual .Signal Processing
The Astro FFT system processes two separate signal sources. Normally these signal sources are the two, mixed down, signal polarization's received from the dish antenna. Each signal is processed by an FPGA based processing engine. Each FPGA based processing engine has two analogue input 14 bit samplers operating at 50 MHz each with an anti-aliasing filter. This allows the FFT engine to operate with a quadrature signal source to improve FFT resolution. More information on the signal processing is in the System specifications Manual.User Information
- User Manual
- AstroGui User Manual
- AstroDataConv User Manual
- Using the AstroFft system at the University of Bern
System Information
- Software release notes
- Hardware Installation
- Software Installation RedHat/Fedora
- Software Installation Debian
- Software Management
- System specifications
- AstroFft Software API
- FPGA device driver interface
FPGA Board Documentation
- FFT Processing Firmware
- FPGA Processing Board
- Analogue to Digital Convertor Board
- PCI to PMC interface board
Misc
Contacts
BEAM Ltd's Web Site | http://www.beam.ltd.uk |
BEAM Ltd's support | support@beam.ltd.uk |
Alpha Data's web site | http://www.alphadata.co.uk |
Alpha Data email address | info@alphadata.co.uk |