An Ultrasonic Multiple-Access Ranging Core Based on Frequency Shift Keying Towards Indoor Localization

Area of Science:

• Robotics and Automation
• Signal Processing
• Embedded Systems

Background:

• Accurate indoor positioning is crucial for various applications.
• Existing ranging technologies face limitations in real-time, multi-transmitter tracking.
• Ultrasound-based systems offer potential for low-power, embedded solutions.

Purpose of the Study:

• To develop a novel indoor ranging system using ultrasound time difference of arrival.
• To implement a real-time, low-power tracking system for multiple simultaneous transmitters.
• To evaluate the accuracy and precision of the proposed ranging methodology.

Main Methods:

• Utilized code division multiple access (CDMA) with ultrasound signals.
• Developed a field-programmable gate array (FPGA) implementation with finite impulse response (FIR) filters.
• Employed frequency shift keying (FSK) modulation on orthogonal ultrasound signals (24.5 kHz and 26 kHz).
• Implemented an optimized correlation demodulator for signal recovery.

Main Results:

• Achieved centimeter-level accuracy for distance measurements up to 17 meters.
• Demonstrated simultaneous tracking of up to four transmitters.
• FPGA implementation consumed less than 30% of available logic gates on a Spartan-6 device.
• Validated ranging accuracy across single-transmitter, dual-transmitter, and trilateration topologies.

Conclusions:

• The proposed FPGA-based ultrasound ranging system provides a robust solution for real-time indoor positioning.
• The system supports simultaneous tracking of multiple transmitters with high accuracy and low power consumption.
• This methodology enhances possibilities for embedded and low-power tracking applications.