Ultrasonic Locationing Dual Phase Pulse Noise Rejection
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Ultrasonic locationing systems face challenges due to noise interference and short pulse duration, which complicates accurate signal detection and location measurement, particularly in environments with broadband noise events.
Innovation Solution
The implementation of dual phase pulses in ultrasonic emissions, where two consecutive frequency bursts with the same frequency but different phases are used, allowing for phase-based validation of pulses and correction for Doppler effects through motion vector analysis.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If ultrasonic pulses are made very short in duration to prevent reflections from arriving before the direct signal, then measurement precision is improved, but reliability deteriorates due to susceptibility to impact noise and poor frequency selectivity
Solution Approach 1:
The ultrasonic pulse is segmented into two distinct phases: a first phase with a first frequency and a second phase with a second frequency. This segmentation allows the receiver to distinguish valid pulses from noise by detecting the specific two-phase structure, thereby improving reliability while maintaining the short duration needed for precise location measurement.
Solution Approach 2:
The invention changes the frequency parameter within the pulse by using two different frequencies in two consecutive phases. This parameter change creates a distinctive signature that enables reliable pulse detection through frequency discrimination, solving the problem of noise susceptibility in short-duration pulses.
2Loss of time
If ultrasonic pulses are made very short in duration, then loss of time is reduced, but loss of information increases due to limited information that can be added to the burst
Solution Approach 1:
By segmenting the pulse into two frequency phases, the invention encodes additional information (frequency sequence pattern) within the short duration. This allows the pulse to carry distinctive identification information without extending the overall transmission time, thus resolving the contradiction between time efficiency and information content.
Solution Approach 2:
The invention uses frequency parameter changes between two phases to encode information. By varying the frequency parameter rather than extending pulse duration, the system embeds additional information about the pulse source while maintaining short transmission time.
3Object-affected harmful factors
If broadband noise filtering is applied to remove impact noise, then object-affected harmful factors are reduced, but measurement precision deteriorates because the desired signal is also filtered out
Solution Approach 1:
Instead of applying broad filtering that affects the entire frequency band, the invention uses local quality discrimination by detecting the specific two-phase frequency structure. The receiver is tuned to recognize this local pattern, allowing it to distinguish valid signals from broadband noise without filtering out the desired signal.
Solution Approach 2:
The invention changes from amplitude-based detection to frequency-based detection by using two distinct frequencies in two phases. This parameter change enables the system to reject broadband noise that does not match the expected frequency sequence, improving signal detection accuracy without losing the desired signal.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach enhances the accuracy of time difference of arrival measurements and effectively distinguishes valid pulses from noise, improving locationing performance while maintaining signal quality and reducing false triggers.
Implementation Method 1
The ultrasonic emitter can transmit ultrasonic energy in a short burst which can be received by an ultrasonic transducer (microphone) in the ultrasonic receiver
Implementation Method 2
correcting for Doppler effects using vector information derived from a position history of the mobile device
Data Source
AI summary
An ultrasonic locationing system using a dual phase pulse includes an emitter emitting two consecutive frequency bursts, each having a different phase, within one ultrasonic pulse. A receiver microphone receives the ultrasonic pulse, and a processor runs an amplitude-based detection algorithm on the pulse for a band of frequencies of interest and detects a first burst of the pulse within the proper frequency band and having an amplitude exceeding a threshold. Whereupon, the processor determines a relative phase difference between the first burst and a second burst of the pulse and determines whether the relative phase difference is within a predetermined acceptance window, indicating that the pulse is valid for use in locationing the emitter and associated mobile device.