Development and Development and Implementation of a FPGA-based Implementation of a FPGA-based

digital beamformerdigital beamformer

Supervisors:Supervisors: Nandita BhattacharjeeNandita Bhattacharjee Dr. Andrew PaplinskiDr. Andrew Paplinski

Dale Harders

Presentation OutlinePresentation Outline

– An Ultrasonic Imaging System OverviewAn Ultrasonic Imaging System Overview

– Beamforming FundamentalsBeamforming Fundamentals

– Significance of studySignificance of study

– Simulator role within this projectSimulator role within this project

– ImplementationImplementation

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Ultrasonic Imaging System OverviewUltrasonic Imaging System Overview

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Spatial FilterSpatial Filter- Only extract desired Only extract desired directionaldirectional data data- Remaining signals are attenuatedRemaining signals are attenuated

Beamforming FundamentalsBeamforming Fundamentals

What is a beamformer?What is a beamformer?

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Focussing subsystemFocussing subsystem- Electronic vs. MechanicalElectronic vs. Mechanical- Sharper images are producedSharper images are produced

Beamforming FundamentalsBeamforming Fundamentals

Consider how an ultrasonic imaging system operatesConsider how an ultrasonic imaging system operates

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How is this focussing achieved digitally?How is this focussing achieved digitally?

Beamforming FundamentalsBeamforming Fundamentals

Possible SolutionPossible Solution:: Delay in time Delay in time

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DisadvantagesDisadvantages:: Large storage requirements Large storage requirements High clock rates required for fine delaysHigh clock rates required for fine delays

A rotation of complex data in the frequency A rotation of complex data in the frequency domain is equivalent to a time delay in the time domain is equivalent to a time delay in the time domain.domain.

Beamforming FundamentalsBeamforming Fundamentals

Better SolutionBetter Solution:: Phase-shiftPhase-shift via complex vector rotation via complex vector rotation

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Process data in a different DomainProcess data in a different Domain- requires Quadrature sampling (Re, Im)requires Quadrature sampling (Re, Im)

AdvantagesAdvantages:: Relatively small digital circuitry required Relatively small digital circuitry required Lower sampling rates requiredLower sampling rates required

Significance of StudySignificance of Study

Increase Image ResolutionIncrease Image Resolution - Improve Signal-to-noise ratio- Improve Signal-to-noise ratio

Maintain fast frame-ratesMaintain fast frame-rates - Real-time imaging- Real-time imaging

Develop 3D-imaging techniquesDevelop 3D-imaging techniques

Ultimate GoalsUltimate Goals

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Continuation of Previous Research @ MonashContinuation of Previous Research @ Monash- (Hampson G, 1998), (Bhattacharjee et al, 2000)(Hampson G, 1998), (Bhattacharjee et al, 2000)

- (Prain R, 2001)(Prain R, 2001)

Simulator role within this projectSimulator role within this project

Ultrasound simulation programUltrasound simulation program - Developed by Joergen Jensen, DenmarkDeveloped by Joergen Jensen, Denmark - Running under MatlabRunning under Matlab

Capable of emulating Capable of emulating allall sub-systems sub-systems

Field IIField II

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(Jensen, 1996)

Simulator role within this projectSimulator role within this project

Field II ExampleField II Example Origin

0-x +x0

+z

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Simulator role within this projectSimulator role within this project

Field II ExampleField II Example

Dale Harders

Simulator role within this projectSimulator role within this project

Field II ExampleField II ExampleOrigin

Dale HardersDale Harders

ImplementationImplementation

Dale HardersDale Harders

Hardware systemHardware system- Two word-parallel, fully pipelined, CORDIC vector rotators Two word-parallel, fully pipelined, CORDIC vector rotators

operating in paralleloperating in parallel- Summing performed on chipSumming performed on chip

Design implemented on a Design implemented on a XilinxXilinx Spartan IISpartan II FPGA FPGA

Device DriverDevice Driver- Interfaced PCI communications API to MatlabInterfaced PCI communications API to Matlab

Developed System - Block Schematic Next Slide…

Beamformer SystemBeamformer System

ACCUMULATOR

ConclusionConclusion

Dale HardersDale Harders

Stable Development Platform builtStable Development Platform built- Easy to use interface for new design test-benchingEasy to use interface for new design test-benching

PCI communicationsPCI communications - Developed a PCI communications interface between Matlab Developed a PCI communications interface between Matlab

and the Hardware for design verification and future and the Hardware for design verification and future

development accelerationdevelopment acceleration

Project deliverables satisfiedProject deliverables satisfied- Successfully implemented a hardware digital beamformerSuccessfully implemented a hardware digital beamformer

References

Bhattacharjee N, Paplinski A and Hampson G, "Phase-shift Beamforming", TR 2000/53, CSSE , Monash

University, Clayton, 2000

Hampson G.A, "Implementing Multi-Dimensional Digital Hardware

Beamformers", PhD thesis, Faculty of Computing andInformation Technology. Monash University, Clayton,1998.

Jensen J.A, "Field: A program for simulating ultrasound systems",

10th Nordic-Baltic Conference on Biomedical Imaging,vol 4, pg 351-353, 1996.

Prain R, “Parallel CORDIC implementation for hardware

beamformers”, Honours Thesis, Department of CSSE, Monash University, Clayton, 2001. Dale Harders