Time-Stamped Pressure Sensor Output for Low-Latency Rate Measurement
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Solution Overview
Problem
Current air data sensors in avionics face challenges in providing precise, low-noise, low-latency pressure measurements due to signal aliasing and noise issues, which are exacerbated by discrete sampling and inadequate filtering, leading to reduced accuracy and increased latency in altitude and airspeed control.
Innovation Solution
An integrated sensor system that embeds synchronous time-stamping with pressure measurements, allowing for low-noise rate-of-change calculations with minimal latency by using a sigma-delta A/D converter and internal data acquisition, enabling external computation of precise pressure and rate parameters without the latency penalty of digital filtering.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If prefiltering is applied to minimize aliasing and noise in discrete sampling systems, then measurement precision is improved, but latency increases and system responsiveness decreases
Solution Approach 1:
The patent replaces the traditional mechanical/discrete sampling approach with a continuous sigma-delta modulation system. Instead of using discrete sampling with prefiltering, the system employs continuous modulation that inherently anti-aliases signals, eliminating the need for separate prefiltering stages and reducing latency while maintaining measurement precision.
Solution Approach 2:
The patent changes the fundamental parameter of signal acquisition from discrete sampling to continuous modulation. By using sigma-delta modulation, the system transforms the signal representation method, allowing for inherent anti-aliasing without the latency penalties of traditional prefiltering approaches.
2Measurement precision
If heavy filtering is applied to reduce noise in rate parameter measurements, then measurement precision is improved, but latency increases
Solution Approach 1:
The patent replaces traditional filtering methods with synchronous time-stamping and external computation of rate parameters. By accurately timestamping each measurement and computing derivatives externally, the system avoids the latency inherent in heavy filtering while maintaining precision in rate parameter measurements.
Solution Approach 2:
The patent performs preliminary action by embedding synchronous time-stamps with each measurement at the source. This pre-prepared timing information enables accurate rate calculations to be performed externally without requiring latency-inducing filtering operations, as the precise timing data is already available.
3Device complexity
If discrete sampling is used in air data sensors, then device complexity is reduced, but measurement precision deteriorates due to aliasing and noise
Solution Approach 1:
The patent substitutes discrete sampling with continuous sigma-delta modulation. This replacement maintains relative simplicity while dramatically improving measurement precision by inherently anti-aliasing the signal and reducing noise, eliminating the need for complex prefiltering circuits.
Solution Approach 2:
The patent makes the sensor system multi-functional by integrating both pressure sensing and precise time-stamping capabilities within the same device. This universal approach allows the single sensor to provide both magnitude and timing information, enabling accurate rate parameter computation without requiring additional specialized components.
4Measurement precision
If smart sensors with internal microcomputers are used to perform high accuracy pressure measurements, then measurement precision is improved, but the capability to simultaneously perform high resolution rate measurements with low latency is inadequate
Solution Approach 1:
The patent extracts the time-stamping function from the smart sensor's microcomputer and implements it through dedicated hardware circuitry. This extraction allows the sensor to simultaneously provide high-accuracy pressure measurements with precise timing information, enabling external systems to compute rate parameters at high speeds without being bottlenecked by the sensor's processing capabilities.
Solution Approach 2:
The patent replaces the software-based processing approach of smart sensors with hardware-based synchronous time-stamping. This substitution enables simultaneous high-accuracy magnitude measurements and high-resolution timing data to be provided through the same interface, dramatically improving the system's ability to perform low-latency rate measurements.
Data Source
AI summary
An integrated sensor implementation employs a data acquisition method for producing digital output signals that enables computing low latency, low noise, rate of pressure (or altitude etc.) change measurements. An example sensor includes a self-digitizing pressure and temperature sensor circuit that outputs a serial digital signal that varies with at least one physical parameter to which the sensor circuit is exposed. The sensor incorporates an internal sigma-delta A/D converter and digital data acquisition device that effectively time-stamps all acquired data. This time stamped data is then transmitted to an external processing resource (microprocessor) that is used to convert the self-digitized, time stamped data into low latency, low-noise proportional and rate parameter outputs having the desired engineering units for at least one physical parameter sensed. This low-latency, low noise rate of change signal may be derived without the latency penalty of digital filtering.