475 research outputs found
An ECG-on-Chip with QRS Detection & Lossless Compression for Low Power Wireless Sensors
IEEE Transactions on Circuits and Systems II: Express BriefsPP991-
Efficient QRS complex detection algorithm implementation on SOC-based embedded system
This paper studies two different Electrocardiography ( ECG ) preprocessing algorithms , namely Pan and Tompkins (PT) and Derivative Based (DB) algorithm, which is crucial of QRS complex detection in cardiovascular disease detection . Both algorithms are compared in terms of QRS detection accuracy and computation timing performance , with implementation on System - on - C hip (SoC) based embedded system that prototype on Altera DE2 - 115 Field Programmable Gate Array (FPGA) platform as embedded software . Both algorithm s are tested with 30 minutes ECG data from each of 48 different patient records obtain from MIT - BIH arrhythmia database. Results show that PT algorithm achieve 98.15% accuracy with 56. 33 seconds computation while DB algorithm achieve 96.74% with only 22. 14 seconds processing time. Based on the study, an optimized PT algorithm with improvement on Moving Windows Integrator (MWI) has been proposed to accelerate its computation. Result show s that the proposed optimized Moving Windows Integrator algorithm achieve s 9.5 times speed up than original MWI while retaining its QRS detection accuracy
Data Conversion Within Energy Constrained Environments
Within scientific research, engineering, and consumer electronics, there is a multitude of new discrete sensor-interfaced devices. Maintaining high accuracy in signal quantization while staying within the strict power-budget of these devices is a very challenging problem. Traditional paths to solving this problem include researching more energy-efficient digital topologies as well as digital scaling.;This work offers an alternative path to lower-energy expenditure in the quantization stage --- content-dependent sampling of a signal. Instead of sampling at a constant rate, this work explores techniques which allow sampling based upon features of the signal itself through the use of application-dependent analog processing. This work presents an asynchronous sampling paradigm, based off the use of floating-gate-enabled analog circuitry. The basis of this work is developed through the mathematical models necessary for asynchronous sampling, as well the SPICE-compatible models necessary for simulating floating-gate enabled analog circuitry. These base techniques and circuitry are then extended to systems and applications utilizing novel analog-to-digital converter topologies capable of leveraging the non-constant sampling rates for significant sample and power savings
An Error-Based Approximation Sensing Circuit for Event-Triggered, Low Power Wearable Sensors
Event-based sensors have the potential to optimize energy consumption at
every stage in the signal processing pipeline, including data acquisition,
transmission, processing and storage. However, almost all state-of-the-art
systems are still built upon the classical Nyquist-based periodic signal
acquisition. In this work, we design and validate the Polygonal Approximation
Sampler (PAS), a novel circuit to implement a general-purpose event-based
sampler using a polygonal approximation algorithm as the underlying sampling
trigger. The circuit can be dynamically reconfigured to produce a coarse or a
detailed reconstruction of the analog input, by adjusting the error threshold
of the approximation. The proposed circuit is designed at the Register Transfer
Level and processes each input sample received from the ADC in a single clock
cycle. The PAS has been tested with three different types of archetypal signals
captured by wearable devices (electrocardiogram, accelerometer and respiration
data) and compared with a standard periodic ADC. These tests show that
single-channel signals, with slow variations and constant segments (like the
used single-lead ECG and the respiration signals) take great advantage from the
used sampling technique, reducing the amount of data used up to 99% without
significant performance degradation. At the same time, multi-channel signals
(like the six-dimensional accelerometer signal) can still benefit from the
designed circuit, achieving a reduction factor up to 80% with minor performance
degradation. These results open the door to new types of wearable sensors with
reduced size and higher battery lifetime
An analogue approach for the processing of biomedical signals
Constant device scaling has signifcantly boosted electronic systems design in the digital domain enabling incorporation of more functionality within small silicon area and at the same time allows high-speed computation. This trend has been exploited for developing high-performance miniaturised systems in a number of application areas like communication, sensor network, main frame computers, biomedical information processing etc. Although successful, the associated cost comes in the form of high leakage power dissipation and systems reliability. With the increase of customer demands for smarter and faster technologies and with the advent of pervasive information processing, these issues may prove to be limiting factors for application of traditional digital design techniques. Furthermore, as the limit of device scaling is nearing, performance enhancement for the conventional digital system design methodology cannot be achieved any further unless innovations in new materials and new transistor design are made. To this end, an alternative design methodology that may enable performance enhancement without depending on device scaling is much sought today.Analogue design technique is one of these alternative techniques that have recently gained considerable interests. Although it is well understood that there are several roadblocks still to be overcome for making analogue-based system design for information processing as the main-stream design technique (e.g., lack of automated design tool, noise performance, efficient passive components implementation on silicon etc.), it may offer a faster way of realising a system with very few components and therefore may have a positive implication on systems performance enhancement. The main aim of this thesis is to explore possible ways of information processing using analogue design techniques in particular in the field of biomedical systems
Adaptive signal processing techniques to detect time-varying late potentials on a beat-to-beat basis
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