Now showing 1 - 10 of 91
  • Publication
    Fast Mode Decision With Early Termination For H.264/AVC Video Coding
    (The Institute of Engineering and Technology (IET), 2006-10-28) ;
    In this paper a fast mode decision algorithm based on an early termination procedure is proposed for H.264/AVC video encoding. Unlike previous methods, the termination decision is based on the rate distortion cost function. A statistical analysis of the spatio-temporal characteristics of the rate distortion cost function and of the probability of mode transition is given for test sequences. Experimental results show that the new algorithm provides a 38% reduction in total computational complexity with a negligible increase in the bit rate and negligible reduction in visual quality when compared to conventional encoding.
  • Publication
    Low Power Real-Time Seizure Detection for Ambulatory EEG
    Ambulatory Electroencephalograph (AEEG) technology is becoming popular because it facilitates the continuous monitoring of epilepsy patients without interrupting their routine life. As long term monitoring requires low power processing on the device, a low power real time seizure detection algorithm suitable for AEEG devices is proposed herein. The performance of various classifiers was tested and the most effective was found to be the Linear Discriminant Analysis classifier (LDA). The algorithm presented in this paper provides 87.7 (100–70.2)% accuracy with 94.2 (100–78)% sensitivity and 77.9 (100–52.1)% specificity in patient dependent experiments. It provides 76.5 (79.0–73.3)% accuracy with 90.9 (96.2–85.8)% sensitivity and 59.5 (70.9–52.6)% specificity in patient independent experiments. We also suggest how power can be saved at the lost of a small amount of accuracy by applying different techniques. The algorithm was simulated on a DSP processor and on an ASIC and the power estimation results for both implementations are presented. Seizure detection using the presented algorithm is approximately 100% more power efficient than other AEEG processing methods. The implementation using an ASIC can reduce power consumption by 25% relative to the implementation on a DSP processor with reduction of only 1% of accuracy.
  • Publication
    Acute ankle sprain injury alters kinematic and centre of pressure measures of postural control during single limb stance
    Background: Upright single-limb stance (SLS) is maintained via integration of visual, vestibular and somatosensory afferents. The presence of redundancies between these afferents allows the sensorimotor system to simplify a specific task within a number of strategies. Musculoskeletal injury challenges the somatosensory system to reweight distorted sensory afferents. No current investigation has supplemented kinetic analysis of eyes-open and eyes-closed SLS tasks with a kinematic profile of lower limb postural orientation in an acute lateral ankle sprain (LAS) group to assess the adaptive capacity of the sensorimotor system to injury. Objective: To compare centre of pressure (COP) and lower limb postural orientation characteristics of participants with acute LAS to non-injured participants during a SLS task. Design Cross-sectional: Setting University biomechanics laboratory. Participants: 66 participants with acute LAS completed a task of eyes-open SLS on their injured and non-injured limbs (task 1). 23 of these participants successfully completed the SLS task with their eyes closed (task 2). A non-injured control group of nineteen participants completed task 1, with 16 completing task 2. Main outcome measures: 3D kinematics of the hip, knee and ankle joints as well as associated fractal dimension (FD) of the COP path. Results: Between trial analyses of groups revealed significant differences in lower limb kinematics and FD of the COP path for task 2. Post-hoc testing revealed that non-injured control group bilaterally assumed a position of greater hip flexion compared to LAS participants (injured limb=7.41±6.1◦ vs 1.44±4.8◦; non-injured limb=9.59±8.5◦ vs 2.16±5.6◦), with a corollary of greater FD of the COP path (injured limb=1.39±0.16 vs 1.25±0.14; non-injured limb=1.37±0.21 vs 1.23±0.14). Conclusion: Acute LAS causes bilateral impairment in postural control strategies.
  • Publication
    Overview of Software Level Power Consumption Models and Power Saving Techniques for Embedded DSP Processors
    Unlike DSP compilation for high performance, research for low power optimisation has received little attention, although power dissipation is a critical issue for mobile devices. This paper presents an overview of power consumption models and power saving techniques for embedded DSP processors applications and evaluates their application to the Texas Instruments TMS320VC5510 Digital Signal Processor. Software level power consumption models introduced in the literatureare presented, along with their advantages and disadvantages. Several power saving techniques are presented, discussing their relevance for the VC5510 processor architecture. The significance of various instruction components with respect to consumption are considered in detail.
  • Publication
    Adapting and Parameterising Auditory Icons for use in a Synthetic Musical Instrument
    (The Institution of Engineering and Technology., 2009-06-10) ; ;
    In this paper we describe the adaptation and parameterization of environmental auditory event structures for use in a real-time musical synthesizer. In doing so, we have developed a new software musical instrument based on the parametric representation of ecological sound structures, and which facilitates the application of typically non-musical auditory events in a musical context. Since this approach is to be realised within a low-latency, performance oriented synthesizer, our aim is not the development of computationally expensive physical models, but rather to effectively convey complex auditory events using arrays of simple sinusoidal components, while still retaining the key perceptual features of those events. By offering a performer ecologically-derived parameter control, we aim to encourage an Everyday Listening approach to electronic music performance, while also allowing the user to combine and develop typically unrelated elements of environmental auditory events.
  • Publication
    Non-Line of Sight Mitigation using a Measurement and Positioning Filtering Algorithm
    In recent years, research interest in location systems has increased due to the emergence of mobile computing devices and the promise of Ubiquitous Computing. This paper considers the problem arising in ultrasonic location systems of Non-Line of Sight (NLOS) between Base Stations and Mobile Devices, which can give significant location errors. Herein, a Dual Kalman Filtering method is proposed to mitigate NLOS effects, using an a-priori partial knowledge of the ultrasonic signals. The main advantage of this method is that the first filter provides a set of filtered ranges that mitigates the NLOS ranging error, while the second filter, by taking these measurements, provides a second positioning filtering that mitigates the overall positioning error. The method is shown to reduce location errors providing a maximum error in location of 9cm.
  • Publication
    WLAN Indoor Ranging Dataset for Evaluation of Time of Arrival Estimation Algorithms
    This paper describes a dataset of WLAN (Wireless Local Area Network, WiFi, IEEE 802.11g/n) ranging signals recorded in an indoor environment for the purposes of time of arrival (TOA) estimation. The dataset contains signals captured in four experimental configurations, with two different clocking techniques, at ranges from 0.5 m to 25 m, and using two different symbols - the 802.11 standard long training sequence and an impulsive symbol. It is expected that the dataset will facilitate development and benchmarking of improved algorithms for TOA estimation in WLAN systems.
  • Publication
    Diverse Double Modular Redundancy: A New Direction for Soft Error Detection and Correction
    Soft errors are becoming an important issue for deep submicron technologies. To protect circuits against soft errors, designers routinely introduce modular redundancy to detect and correct these errors. A commonly used technique, Double Modular Redundancy (DMR) involves duplication of the basic module. Conventionally, DMR only allows error detection since voting cannot be used to determine the module in error. Recently, however, it has been found that DMR can, for some circuits, be enhanced to provide soft error correction as well as detection. The general approach, DDMR (Diverse DMR), relies on introducing design diversity between the original and redundant modules so that they produce different error patterns when a soft error occurs. The module in error can be found by examining these patterns. Herein, the generalized approach is described. A number of techniques for producing diverse designs with distinct error patterns are identified and illustrated with examples. New DDMR solutions are presented and finally, the future direction of DDMR research is discussed.
      396Scopus© Citations 24
  • Publication
    Accuracy of Spread Spectrum Techniques for Ultrasonic Indoor Location
    This paper presents an assessment of the accuracy of impulsive and spread spectrum based algorithms for indoor ultrasonic location. Ultrasonic location systems have been proposed for pervasive computing applications. Previous systems have focused on the use of impulsive and Direct Sequence Spread Spectrum (DSSS) signalling. The use of Frequency Hopped Spread Spectrum (FHSS) signalling has not been previously studied for ultrasonic location. It is shown herein that FHSS outperforms DSSS and impulsive signalling under conditions of noise and reverberation. The accuracy of location for FHSS is shown to be twice that of DSSS under typical conditions. FHSS also provides opportunities for simplified transducer construction.
      545Scopus© Citations 21
  • Publication
    Extending the Lifetime of Sensor Networks Using Prediction and Scheduling
    Power consumption in wireless sensor networks (WSNs) is a very important issue. Using measured sensor network data, this paper shows that it is possible to conserve a significant amount of energy through the proper use of data prediction and node scheduling without a significant loss in accuracy. Results show that it is possible to increase lifetime by up to 2600% at the cost of increasing average error by 0.5degC for temperature or 1.5% for humidity measurements. The four main design issues tackled are clustering, prediction, scheduling, and spike errors.
      245Scopus© Citations 6