RF Engines Ltd, Newport, Isle of Wight, UK, the
world-leading supplier of signal processing technology for
FPGA, has announced a new Spectrometer IP core for
FPGA that enables the rapid development of very wideband
spectral analysis systems. The new core is based on RF
Engines’ HyperSpeed Fast Fourier Transform (FFT)
technology, and makes possible unprecedented advances in
radio astronomical receivers that operate in the frequency
domain.
The Max-Planck-Institut für Radioastronomie
(MPIfR), Bonn, is already making use of a 100MHz
Spectrometer core in receivers at its 100 meter radio
telescope and has acknowledged the improvement over
traditional spectrometers. A recent paper, (Astronomy
& Astrophysics, in press) published jointly by the
MPIfR and the Radioastronomisches Institut of Bonn
University, explains how this novel technique far
outperforms existing technologies. It states that the
technique, used for analysis of signals from astronomical
objects, “can be considered prototypical for
spectrometer development in future radio astronomical
applications”, and identifies the significant
improvements in bandwidth, sensitivity and cost.
The new core takes a 1GHz sampled signal at its input
and converts this to a frequency power spectrum, using a
digital band filter and a 16K-point FFT, in continuous
real-time. This enables a 400MHz bandwidth of radio
spectrum with a passband ripple of only 0.001dB to be
analysed with a frequency resolution of 30.5kHz. The
combination of very wide bandwidth and fine resolution
performance has been achieved within a single FPGA device,
ensuring that the technology is both quick to implement and
is extremely cost effective compared with traditional
techniques.
The Spectrometer Core has initially been demonstrated on
the AC210 and AC240 platforms recently announced by Acqiris
(www.acqiris.com). These
high quality platforms include the high speed Analog to
Digital Converter (ADC) required to digitise the signal at
1GHz, and a Xilinx Virtex II Pro 70 FPGA to perform the
signal processing. RF Engines has a roadmap to
enhance the performance of the Spectrometer Core to take
advantage of the full 2GHz sample rate available on the
AC240, and to increase the FFT length to the
32K-points.
“We are extremely pleased to be working with the
Max-Planck-Institut für Radioastronomie in an area
which is pushing the boundaries of receiver
technology,” said John Summers, VP Sales and Business
Development, RF Engines. “Their latest radio
astronomy receiver gives a practical demonstration of the
dramatic technology advances that can be achieved through
the use of FPGA technology and RF Engines’ design
capabilities. This project had particularly
aggressive timescales, and further validates our modular IP
approach to building high performance signal processing
systems.”
Technical Description
The Spectrometer Core receives 8-bit samples from the
ADC at a continuous sample rate of 1GHz, and then processes
this data in four main stages. First, a Half Band
Filter (HBF) converts samples to a complex format, and
reduces the sample rate by a factor of two, which eases the
subsequent processing requirements. This is then
followed by a windowing function, which weights the data in
order to control the filtering performance of the
FFT. The window coefficients are user programmable at
run-time, allowing the performance characteristics of the
system to be modified for changing operational
scenarios.
The 16K-point HyperSpeed FFT forms the central element
of the system, performing the conversion from the
time-domain to frequency-domain, and includes bit reversing
to sort the data in natural frequency order. The FFT
is built using a highly parallel architecture in order to
achieve the very high sample rate.
The final stage of processing is to convert the
frequency spectrum to a power representation, and
accumulate successive results. This accumulation
stage has the effect of averaging together a number of
power spectra, thereby reducing the background noise and
improving the detection of weak signals. This stage
also helps to reduce the amount of data produced by the
system, and eases any subsequent interface bandwidth
requirements and processing loads. Output from the
core is in a 32-bit floating-point format, which allows
data to be efficiently post-processed by a standard desktop
computer.
The core is supported by a bit-true model, which allows
potential users to simulate the core within their own
particular signal environment. This allows the precise
performance of the system to be known in advance of the
hardware implementation, and dramatically reduces the risk
of redesign or implementation problems.
A block diagram of RF Engines' 1GHz
Spectrometer Core for FPGA
The Future
RF Engines is already working on enhancements to the
spectrometer system, and has indicated that the next
release of the product will support sample rates up to 2GHz
and transform sizes of 32K-points. This will allow even
wider bandwidths to be analysed or finer resolution spectral
analysis.
In addition to providing an FPGA core for customers to
integrate into their own hardware, RF Engines is also well
progressed towards providing complete Spectral Analysis
solutions, which will include the hardware platform and
graphical user interface software. These systems will
provide users with an “out-of-the-box” solution
to high performance real-time spectral analysis, and will
meet a broad range of applications in the
telecommunications, instrumentation and scientific
industries.
RF Engines
RF Engines Limited (RFEL) is a UK based designer,
providing high specification signal processing cores,
system on chip designs, and FPGA based board solutions for
applications in the defence, communications and
instrumentation markets. These applications include base
stations, wireless and wireline broadband communications
systems, satellite communications systems, test
and measurement instrumentation, as well as defence
systems. More specifically, RFEL is a solutions provider
for projects requiring complex front end, real-time, wide
and narrow band, flexible channelisation. RFEL
provides a range of standard cores covering multiple FFT
and unique PFT techniques, as well as system design
services for specialist applications.
For further information, please see the website at
www.rfel.com or contact RF Engines
at Innovation Centre, St Cross Business Park, Newport,
Isle of Wight, PO30 5WB, Great Britain. Tel +44 (0) 1983
550330. E-mail info@rfel.com
Press information and illustrations can be obtained from
Nigel Robson, Vortex PR, Island House, Forest Road,
Guernsey, GY8 0AB, Great Britain. Tel +44 (0) 1481 233080.
E-mail nigel@vortexpr.com
Max-Planck-Institut für Radioastronomie
The Max-Planck-Institut für Radioastronomie is
based in Bonn, Germany. Technological efforts in the
institute cover the whole spectrum from radio, over
(sub)millimetre, to far-infrared wavelengths. The
institute is currently commissioning a novel submillimetre
wavelength telescope in the Chilean high Atacama desert
(APEX), which will provide unprecedented observing
opportunities. At the earliest possible, the MPIfR will
operate the new spectrometers also at this unique
facility.
For further informations, please see the website at
www.MPIfR-Bonn.MPG.de
or contact Dr. Bernd Klein, head of Digital
Electronics, Max-Planck-Institut für Radioastronomie,
Auf dem Hügel 69, 53121 Bonn, Germany. Tel +49 (0) 228
525-286. E-mail bklein@MPIfR-Bonn.MPG.de