Contributions to adaptive equalization and timing recovery for optical storage systems

no abstrac

Available Techniques for Magnetic Hard Disk Drive Read Channel Equalization

This paper presents an extensive, non-exhaustive, study of available hard disk drive read channel equalization techniques used in the storage and readback of magnetically stored information. The physical elements and basic principles of the storage processes are introduced together with the basic theoretical definitions and models. Both read and write processes in magnetic storage are explained along with the definition of simple key concepts such as user bit density, intersymbol interference, linear and areal density, read head pulse response models, and coding algorithm

A review of the processes and effects of droughts and summer floods in rivers and threats due to climate change on current adaptive strategies

Europe is expected to experience a greater frequency of floods and droughts as precipitation and evapotranspiration patterns are modified by climate change in future. Several large scale drought and flooding events have occurred in Europe since 2000. Studies of drought are rare but indicate important impacts on freshwater habitats, water quality, plants and animals, which may have wider consequences for ecosystem functioning. The main factors determining the impacts of droughts and floods are event duration and seasonality of the event. A diverse habitat distribution and the presence of refugia at the reach scale confer the most resilience against droughts and floods. Management measures will also be impacted particularly with regard to riparian zones, channel morphology, flow and floodplain connectivity. However there is a conflict between management actions that target the effects of drought, and those that target floods. This report reviews information on droughts and aseasonal floods (summer floods) published since 2000 with a principal focus on small lowland rivers. Using several recent (post 2000) reviews on these topics, we describe abiotic and biotic effects of droughts and floods, providing recent European examples where possible. We explain the current status of droughts and summer floods in Europe, and where the main sources of data can be found. We highlight the threats posed by these phenomena to some of the most common current adaptive management strategies in place in the EU. To this end we use measures already described within REFRESH under Deliverables 1.1 and 1.2, and we focused solely on adaptive measures relating to riparian zones, channel morphology, flow and floodplain connectivity

RAPID CLOCK RECOVERY ALGORITHMS FOR DIGITAL MAGNETIC RECORDING AND DATA COMMUNICATIONS

SIGLEAvailable from British Library Document Supply Centre-DSC:DXN024293 / BLDSC - British Library Document Supply CentreGBUnited Kingdo

Enhanced coding, clock recovery and detection for a magnetic credit card

Merged with duplicate record 10026.1/2299 on 03.04.2017 by CS (TIS)This thesis describes the background, investigation and construction of a system for storing data on the magnetic stripe of a standard three-inch plastic credit in: inch card. Investigation shows that the information storage limit within a 3.375 in by 0.11 in rectangle of the stripe is bounded to about 20 kBytes. Practical issues limit the data storage to around 300 Bytes with a low raw error rate: a four-fold density increase over the standard. Removal of the timing jitter (that is prob-' ably caused by the magnetic medium particle size) would increase the limit to 1500 Bytes with no other system changes. This is enough capacity for either a small digital passport photograph or a digitized signature: making it possible to remove printed versions from the surface of the card. To achieve even these modest gains has required the development of a new variable rate code that is more resilient to timing errors than other codes in its efficiency class. The tabulation of the effects of timing errors required the construction of a new code metric and self-recovering decoders. In addition, a new method of timing recovery, based on the signal 'snatches' has been invented to increase the rapidity with which a Bayesian decoder can track the changing velocity of a hand-swiped card. The timing recovery and Bayesian detector have been integrated into one computation (software) unit that is self-contained and can decode a general class of (d, k) constrained codes. Additionally, the unit has a signal truncation mechanism to alleviate some of the effects of non-linear distortion that are present when a magnetic card is read with a magneto-resistive magnetic sensor that has been driven beyond its bias magnetization. While the storage density is low and the total storage capacity is meagre in comparison with contemporary storage devices, the high density card may still have a niche role to play in society. Nevertheless, in the face of the Smart card its long term outlook is uncertain. However, several areas of coding and detection under short-duration extreme conditions have brought new decoding methods to light. The scope of these methods is not limited just to the credit card