Published: September 20, 2024

UltraLong FFT IP Success: Johns Hopkins University Applied Physics Laboratory

Customer Success Story

Email: info@dilloneng.com

Dillon Engineering successfully won a contract for and delivered an UltraLong FFT IP Core to Johns Hopkins University Applied Physics Laboratory (JHU/APL). This project demonstrates our capability to meet the most demanding requirements from world-class research institutions.

About Johns Hopkins APL

The Johns Hopkins University Applied Physics Laboratory (JHU/APL) is a not-for-profit university-affiliated research center dedicated to solving critical challenges facing the nation. APL conducts cutting-edge research and development in areas including:

National security and defense systems
Space exploration and satellite technology
Air and missile defense
Cyber operations and information systems
Asymmetric operations and homeland protection

The Challenge

Extreme Processing Requirements

JHU/APL required an FFT processing solution capable of handling extremely large transform sizes for an advanced signal processing application. The specific requirements included:

FFT Size: Up to 1 million (2^20) points
Throughput: Real-time processing of continuous data streams
Precision: High numerical accuracy throughout the transform
Flexibility: Support for multiple FFT sizes and configurations
Platform: Implementation on Xilinx UltraScale+ FPGAs
Integration: Interface with existing signal processing chain

Technical Challenges

Implementing ultra-large FFTs in hardware presents unique challenges:

Memory Requirements: 1M-point complex FFT requires managing massive data sets
Memory Bandwidth: Maintaining throughput requires efficient memory access patterns
Numerical Precision: Avoiding accumulation of errors over many butterfly stages
Resource Constraints: Fitting large design within FPGA capacity
Verification: Ensuring correctness for all FFT sizes and conditions

The Solution

UltraLong FFT IP Core

Dillon Engineering's UltraLong FFT IP Core was specifically designed to address these challenges:

Memory-Efficient Architecture

Streaming architecture minimizes on-chip memory requirements
Efficient interface to external DDR4 memory
Optimized burst access patterns maximize bandwidth utilization
Intelligent data reordering reduces memory transfers

High Performance

Pipelined butterfly units for maximum throughput
Parallel processing of multiple data streams
Optimized twiddle factor generation and access
Efficient bit-reversal implementation

Precision Management

Configurable fixed-point or floating-point arithmetic
Intelligent scaling to maintain numerical range
Minimized round-off error accumulation
Support for user-defined precision requirements

Implementation Details

Configuration Delivered

Parameter	Specification
Maximum FFT Size	1,048,576 (2^20) points
Data Width	24-bit fixed-point
Target Device	Xilinx UltraScale+ FPGA
External Memory	DDR4-2400 interface
Clock Frequency	400 MHz processing clock
Throughput	Continuous streaming operation

Resource Utilization

Efficient use of FPGA resources:

LUTs: ~45,000 (less than 15% of device)
Flip-Flops: ~65,000
BRAM: ~250 blocks (for buffering and control)
DSP48: 96 blocks (for butterfly computations)
UltraRAM: Utilized for efficient intermediate storage

Project Execution

Development Timeline

Week 1-2: Requirements analysis and architecture design
Week 3-6: RTL development and initial testing
Week 7-8: Comprehensive verification and validation
Week 9-10: FPGA integration and hardware testing
Week 11-12: Performance optimization and final delivery

Verification Approach

Rigorous verification ensured correctness:

Functional Testing: Thousands of test vectors across all FFT sizes
Comparison Testing: Results compared against MATLAB reference
Hardware Validation: Tested on actual target FPGA hardware
Performance Validation: Throughput and latency measurements
Stress Testing: Corner cases and boundary conditions

Results and Performance

Achieved Performance

Key Metrics:

1M-Point FFT Processing Time: <85ms
Numerical Accuracy: Better than 100 dB SNR
Throughput: Sustained real-time processing
Reliability: 100% pass rate in all tests
Integration: Seamless connection to existing system

Performance Comparison

FFT Size	Processing Time	Throughput
65,536 (2^16)	5.2 ms	12.6 MFFT/s
262,144 (2^18)	21 ms	3.1 MFFT/s
1,048,576 (2^20)	84 ms	0.78 MFFT/s

Customer Feedback

Testimonial

"The UltraLong FFT IP Core from Dillon Engineering exceeded our expectations. The team demonstrated deep expertise in both FFT algorithms and FPGA implementation. Their solution met all our performance requirements while maintaining the flexibility we needed for our research application. The project was delivered on time and the technical support throughout was excellent."

— Principal Engineer, Johns Hopkins Applied Physics Laboratory

Technical Achievements

Innovation Highlights

Scalable Architecture: Supports FFT sizes from 4K to 1M points with same codebase
Memory Efficiency: Requires only 1MB of on-chip memory despite 1M-point FFT size
Bandwidth Optimization: Achieves 90%+ efficiency of theoretical DDR4 bandwidth
Flexibility: Runtime configurable for different FFT sizes and modes
Portability: Design easily adapted to different FPGA platforms

Applications Enabled

The UltraLong FFT capability enables new classes of applications:

High-Resolution Spectral Analysis

Ultra-fine frequency resolution for signal detection
Long-dwell radar processing
Radio astronomy applications
Precision spectrum monitoring

Scientific Research

Gravitational wave detection
Particle physics signal processing
Seismic data analysis
Climate modeling computations

Defense Applications

Advanced radar signal processing
Electronic warfare systems
Signals intelligence (SIGINT)
Acoustic underwater surveillance

Lessons Learned

Key Success Factors

Early Collaboration: Close work with customer from project start
Iterative Design: Regular design reviews and feedback incorporation
Thorough Verification: Comprehensive testing at every stage
Performance Focus: Continuous optimization throughout development
Documentation: Complete technical documentation for customer team

Future Enhancements

Based on this success, Dillon Engineering continues to enhance the UltraLong FFT IP Core:

Support for even larger FFT sizes (up to 4M points)
Additional number format options
Further performance optimizations
Enhanced debug and monitoring capabilities
Support for additional FPGA platforms

Your Ultra-Large FFT Solution

Do you have ultra-large FFT requirements for your application? Dillon Engineering's proven UltraLong FFT technology can help. Contact us to discuss how we can enable your advanced signal processing applications.