59,519 research outputs found
A Study on Measurement Evaluation of DOA Estimation Algorithm using Adaptive Array Antenna
Wireless communication technologies have greatly progressed in recent years and the markets, especially in the mobile communication, have been growing enormously. Moreover the next generation communication services will use higher frequency band, and require more channel capacity and wider bandwidth for a high-speed data communication. As a large increase in channel capacity and high transmission rates for wireless communications, the technologies for the power saving and efficient frequency usability are required. To meet the requirements of the next generation wireless communications, a system capable to automatically change the directionality of its radiation patterns in response to its signal environment must be indispensable.
An adaptive array antenna system uses spatially separated antennas called array antenna and processes received signals with a digital signal processor after analog to digital conversion. The main concept of an adaptive antenna is the automatic or adaptive control of antenna's beam pattern by digital signal processing with a software algorithm. A digital device capable of high speed real-time processing, consuming low power and programmable is required for practical use of an adaptive antenna in wireless communications. In recent year using a FPGA(Field Programmable Gate Array) for the implementation of an adaptive antenna meets the requirements of high performance processing, programmability and low power consumption.
This thesis describes a DOA(Direction Of Arrival) estimation algorithm using MUSIC(MUltiple SIgnal Classification) method with high resolution and evaluation of the DOA estimation measurement system using adaptive array antenna. The DOA estimation measurement system consists of linear array antenna, a DBF receiver, A/D control box and monitoring/control computer in the anechoic chamber. Transmitting part is composed broadband standard horn antenna and signal generator. The linear array antenna is fabricated and measured return loss is -16 dB and below at 2.09 GHz. The DBF(Digital Beam Forming) receiver is composed of 4-ch resistive FET mixer of low IF method. RF(Radio Frequency), LO(Local Oscillator) and an IF(Intermediate Frequency) signal considered in this thesis are 2.09 GHz, 2.08 GHz and 10 MHz, respectively. A/D control box has 12-bit resolution and sampling rates is up to 40 MHz. From results of the DOA estimation simulation using MATLAB, a zero IF is realized by DDC(Digital Down Conversion) and MUSIC algorithm with high resolution depends on the snapshot and antenna element number. In addition, A/D control box is implemented by MUSIC algorithm and IF signal generator. GUI(Graph User Interface) program for data control/monitoring in the computer is designed. From the results of the DOA estimation experiment, it confirms that a proposed DOA system is able to estimate the direction of incident wave.Abbreviations iii
Abstract iv
ì 1 ì„ ì ëĄ 1
1.1 ì°ê”Źë°°êČœ ë° íìì± 1
1.1.1 ì ì ë°°ìŽ ìí
ë 2
1.1.2 FPGA 4
1.1.3 SDR 8
1.2 ì°ê”ŹëȘ©ì 9
ì 2 ì„ ì ì ë°°ìŽ ìí
ë ìì€í
ê”Źì± 11
2.1 ìì êž°ì ê”ŹìĄ° 11
2.1.1 êž°ì ëì ìíë§ 11
2.1.2 IF ìíë§ 13
2.2 A/D 컚ížëĄ€ ë°ì€ 15
2.2.1 A/D 컚ížëĄ€ ë°ì€ì ê”Źì± 15
2.2.2 FPGAì íëĄê”Źí 20
ì 3 ì„ DOA ì¶ì ìêł ëŠŹìŠ 21
3.1 ìëĄ 21
3.2 MUSIC ìêł ëŠŹìŠ 21
3.3 MATLABì ìŽì©í ì럏ë ìŽì
24
3.3.1 DDC 24
3.3.2 NCO 24
3.3.3 LPF 25
3.4 A/D 컚ížëĄ€ ë°ì€ì ì±ë„ìí 33
ì 4ì„ DOA ìžĄì ìì€í
ê”Źì¶ ë° íê° 34
4.1 ë°°ìŽ ìí
ëì ì ì ë° ìžĄì 34
4.2 DOA ì¶ì ëȘšëž 40
4.3 ìžĄì ìì€í
ì±ë„íê° 42
4.3.1 DOA ì¶ì êČ°êłŒ 42
4.3.2 ì€ì°šë°ì ììž ë° êł ì°° 47
ì 5 ì„ êČ° ëĄ 51
ì°žêł ëŹží 5
Digital implementation of the cellular sensor-computers
Two different kinds of cellular sensor-processor architectures are used nowadays in various
applications. The first is the traditional sensor-processor architecture, where the sensor and the
processor arrays are mapped into each other. The second is the foveal architecture, in which a
small active fovea is navigating in a large sensor array. This second architecture is introduced
and compared here. Both of these architectures can be implemented with analog and digital
processor arrays. The efficiency of the different implementation types, depending on the used
CMOS technology, is analyzed. It turned out, that the finer the technology is, the better to use
digital implementation rather than analog
Configurable 3D-integrated focal-plane sensor-processor array architecture
A mixed-signal Cellular Visual Microprocessor architecture with digital processors is
described. An ASIC implementation is also demonstrated. The architecture is composed of a
regular sensor readout circuit array, prepared for 3D face-to-face type integration, and one or
several cascaded array of mainly identical (SIMD) processing elements. The individual array
elements derived from the same general HDL description and could be of different in size, aspect
ratio, and computing resources
Cost-effective aperture arrays for SKA Phase 1: single or dual-band?
An important design decision for the first phase of the Square Kilometre
Array is whether the low frequency component (SKA1-low) should be implemented
as a single or dual-band aperture array; that is, using one or two antenna
element designs to observe the 70-450 MHz frequency band. This memo uses an
elementary parametric analysis to make a quantitative, first-order cost
comparison of representative implementations of a single and dual-band system,
chosen for comparable performance characteristics. A direct comparison of the
SKA1-low station costs reveals that those costs are similar, although the
uncertainties are high. The cost impact on the broader telescope system varies:
the deployment and site preparation costs are higher for the dual-band array,
but the digital signal processing costs are higher for the single-band array.
This parametric analysis also shows that a first stage of analogue tile
beamforming, as opposed to only station-level, all-digital beamforming, has the
potential to significantly reduce the cost of the SKA1-low stations. However,
tile beamforming can limit flexibility and performance, principally in terms of
reducing accessible field of view. We examine the cost impacts in the context
of scientific performance, for which the spacing and intra-station layout of
the antenna elements are important derived parameters. We discuss the
implications of the many possible intra-station signal transport and processing
architectures and consider areas where future work could improve the accuracy
of SKA1-low costing.Comment: 64 pages, 23 figures, submitted to the SKA Memo serie
High accuracy computation with linear analog optical systems: a critical study
High accuracy optical processors based on the algorithm of digital multiplication by analog convolution (DMAC) are studied for ultimate performance limitations. Variations of optical processors that perform high accuracy vector-vector inner products are studied in abstract and with specific examples. It is concluded that the use of linear analog optical processors in performing digital computations with DMAC leads to impractical requirements for the accuracy of analog optical systems and the complexity of postprocessing electronics
A micropower centroiding vision processor
Published versio
Architectures for block Toeplitz systems
In this paper efficient VLSI architectures of highly concurrent algorithms for the solution of block linear systems with Toeplitz or near-to-Toeplitz entries are presented. The main features of the proposed scheme are the use of scalar only operations, multiplications/divisions and additions, and the local communication which enables the development of wavefront array architecture. Both the mean squared error and the total squared error formulations are described and a variety of implementations are given
Development and implementation of an adaptive digital beamforming network for satellite communication systems
The use of adaptive digital beamforming techniques has, until recently, been largely restricted to high performance military radar systems. Recent advances in digital technology, however, have enabled the design of single chip digital beamforming networks. This, coupled with advances in digital signal processor technology, enables complete beamforming systems to be constructed at a lower cost, thus making the application of these techniques to commercial communications systems attractive. The design and development of such an adaptative digital beamforming network are described. The system is being developed as a proof of concept laboratory based demonstrator to enable the feasibility of adaptive digital beamforming techniques for communication systems to be determined. Ultimately, digital beamforming could be used in conjunction with large array antennas for communication satellite systems. This will enable the simultaneous steering of high gain antenna beams in the direction of gr...Peer ReviewedPostprint (published version
A Scalable Correlator Architecture Based on Modular FPGA Hardware, Reuseable Gateware, and Data Packetization
A new generation of radio telescopes is achieving unprecedented levels of
sensitivity and resolution, as well as increased agility and field-of-view, by
employing high-performance digital signal processing hardware to phase and
correlate large numbers of antennas. The computational demands of these imaging
systems scale in proportion to BMN^2, where B is the signal bandwidth, M is the
number of independent beams, and N is the number of antennas. The
specifications of many new arrays lead to demands in excess of tens of PetaOps
per second.
To meet this challenge, we have developed a general purpose correlator
architecture using standard 10-Gbit Ethernet switches to pass data between
flexible hardware modules containing Field Programmable Gate Array (FPGA)
chips. These chips are programmed using open-source signal processing libraries
we have developed to be flexible, scalable, and chip-independent. This work
reduces the time and cost of implementing a wide range of signal processing
systems, with correlators foremost among them,and facilitates upgrading to new
generations of processing technology. We present several correlator
deployments, including a 16-antenna, 200-MHz bandwidth, 4-bit, full Stokes
parameter application deployed on the Precision Array for Probing the Epoch of
Reionization.Comment: Accepted to Publications of the Astronomy Society of the Pacific. 31
pages. v2: corrected typo, v3: corrected Fig. 1
A Wideband, Four-Element, All-Digital Beamforming System for Dense Aperture Arrays in Radio Astronomy
Densely-packed, all-digital aperture arrays form a key area of technology
development required for the Square Kilometre Array (SKA) radio telescope. The
design of real-time signal processing systems for digital aperture arrays is
currently a central challenge in pathfinder projects worldwide. We describe
interim results of such work; an heirarchical, frequency-domain beamforming
architecture for synthesising a sky beam from the wideband antenna feeds of
digital aperture arrays.Comment: 4 pages, 6 figure
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