Look-ahead seek correction in high-performance CD-Rom drives

As the performance of CD-ROM drives continues to increase, special attention should be paid to any element in the system that disturbs the desired specifications. When very low access times are considered, it is mandatory to reach the target track within only one seek action, i.e. without any consequent retry or correction seek. Many CD-ROM drives count the tracks crossed during seeking and, by comparing this count with the pre-calculated seek length, the exact target location can be detected. This paper considers the error that affects the track-counting mechanism due to the rotating disc spiral. It is shown that, for a given seek length, the number of crossed tracks differs between outside- and inside-oriented seeks. The involved equations are derived and an algorithm proposed for determining the correct number of tracks to be crossed during a seek action. The proposed algorithm, which is optimized for microprocessor implementation, relies on two look-up tables and a learning scheme that allows look-ahead seek correction for both spiral rotation and system tolerance

Look-ahead seek correction in high-performance CD-Rom drives

As the performance of CD-ROM drives continues to increase, special attention should be paid to any element in the system that disturbs the desired specifications. When very low access times are considered, it is mandatory to reach the target track within only one seek action, i.e. without any consequent retry or correction seek. Many CD-ROM drives count the tracks crossed during seeking and, by comparing this count with the pre-calculated seek length, the exact target location can be detected. This paper considers the error that affects the track-counting mechanism due to the rotating disc spiral. It is shown that, for a given seek length, the number of crossed tracks differs between outside- and inside-oriented seeks. The involved equations are derived and an algorithm proposed for determining the correct number of tracks to be crossed during a seek action. The proposed algorithm, which is optimized for microprocessor implementation, relies on two look-up tables and a learning scheme that allows look-ahead seek correction for both spiral rotation and system tolerance

<title>Privacy-protected biometric templates: acoustic ear identification</title>

Unique Biometric Identiers oer a very convenient way for human identication and authentication. In contrast to passwords they have hence the advantage that they can not be forgotten or lost. In order to set-up a biometric identication/authentication system, reference data have t

Privacy protected biometric templates: acoustic ear identification

Unique Biometric Identifiers offer a very convenient way for human identification and authentication. In contrast to passwords they have hence the advantage that they can not be forgotten or lost. In order to set-up a biometric identification/authentication system, reference data have to be stored in a central database. As biometric identifiers are unique for a human being, the derived templates comprise unique, sensitive and therefore private information about a person. This is why many people are reluctant to accept a system based on biometric identification. Consequently, the stored templates have to be handled with care and protected against misuse [1, 2, 3, 4, 5, 6]. It is clear that techniques from cryptography can be used to achieve privacy. However, as biometric data are noisy, and cryptographic functions are by construction very sensitive to small changes in their input, and hence one can not apply those crypto techniques straightforwardly. In this paper we show the feasibility of the techniques developed in [5], [6] by applying them to experimental biometric data. As biometric identifier we have choosen the shape of the inner ear-canal, which is obtained by measuring the headphone-to-ear-canal Transfer Functions (HpTFs) which are known to be person dependent [7]