Abstract: Hashes are short summaries or signatures of data files which can be used to identify the file. The disclosed method generates robust hashes for multimedia content, for example, audio clips. The audio clip is divided into successive (preferably overlapping) frames. For each frame, the frequency spectrum is divided into bands. A robust property of each band (e.g. energy) is computed and represented by a respective hash bit. An audio clip is thus represented by a concatenation of binary hash words, one for each frame. To identify a possibly compressed audio signal, a block of hash words derived therefrom is matched by a computer with a large database. Such matching strategies are also disclosed. In an advantageous embodiment, the extraction process also provides information as to which of the hash bits are the least reliable. Flipping these bits considerably improves the speed and performance of the matching process.

Abstract: There is provided a fall detection system, comprising a passive vibration sensor; one or more other sensors for detecting respective characteristics of a fall; and a processor for analyzing measurements from the one or more other sensors to determine if a fall has occurred; wherein the system is configured to selectively provide power to the one or more other sensors and/or processor in response to the passive vibration sensor detecting motion of a user of the fall detection system.

Abstract: A method for driving a light source (11, 12, 13) is described, wherein the light source is alternately switched ON and OFF in an ON/OFF pattern, wherein the duty cycle of the ON/OFF pattern is varied to vary the average light intensity of the light source, and wherein the shape of the ON/OFF pattern is varied to transmit data. Thus, a control signal for the light source comprises data information as well as duty cycle information. The duty cycle is varied within a range from almost zero to almost 100%, and data is varied and transmitted without affecting the duty cycle.

Abstract: In order to efficiently prevent the save-and-restore attack on usage rights associated with digital work, these usage rights are protected by a hidden channel. In order to make it a difficult or expensive to manipulate the hidden channel, a device is proposed comprising: writing means (34) for writing on a record carrier (20) said digital work (DW) and attached usage right information (22) defining one or more conditions to be satisfied in order for the usage right to be exercised,—fingerprint extraction means (23) for deriving fingerprint data (24) from physically uncontrollable, changeable non-uniformities on said record carrier (20), and authentication means (25) for generating authentication data (26) from said fingerprint data (24) and said usage right information (22), said authentication data being provided for authenticating said usage right information, said writing means (34) being adapted for writing said authentication data (25) on said record carrier (20).

Abstract: Hashes are short summaries or signatures of data files which can be used to identify the file. Hashing multimedia content (audio, video, images) is difficult because the hash of original content and processed (e.g. compressed) content may differ significantly. The disclosed method generates robust hashes for multimedia content, for example, audio clips. The audio clip is divided (12) into successive (preferably overlapping) frames. For each frame, the frequency spectrum is divided (15) into bands. A robust property of each band (e.g. energy) is computed (16) and represented (17) by a respective hash bit. An audio clip is thus represented by a concatenation of binary hash words, one for each frame. To identify a possibly compressed audio signal, a block of hash words derived therefrom is matched by a computer (20) with a large database (21). Such matching strategies are also disclosed.

Abstract: In a receiver for processing OFDM encoded signals, wherein the OFDM encoded digital signals are transmitted by means of a symbol in each of subcarrier frequency channels, with at least some of said subcarriers containing user data symbols, an initial estimate of a channel frequency response is formed from magnitudes of user data symbols received in those subcarriers. Then, a correlation function of a channel impulse response is estimated by performing an inverse Fourier transform on the initial estimate of the channel frequency response, and the length of the channel impulse response is estimated by examining peaks in the estimated correlation function of the channel impulse response.

Abstract: A method of decoding possibly mutilated codewords (r) of a code (C) into information words (m?) including information symbols (m?1, m?2, . . . , m?k), the information words (m) being encoded into codewords (c) of the code (C). In order not to considerably deviate from the standard method and apparatus for decoding a standard Reed-Solomon code, a method of decoding is proposed including decoding the possibly mutilated codewords (r) into codewords (r?), reconstructing information symbols (m?1, m?2, . . . , m?k) from the codewords (r?), comparing the reconstruct information symbols (m?1, m?2, . . . , m?k) with information symbols (m1) known a priori before decoding, and verifying decoding errors based on the result of the comparison.

Abstract: In an OFDM mobile communications system, an algorithm for forming a preliminary estimate of the channel on pilot subcarriers is carried out. Based on this preliminary estimate, a channel property is estimated. This channel property is then used to decide whether to enter a mobile receiver mode or a stationary receiver mode. For example, in the mobile mode channel estimation is performed using only pilot symbols from the current symbol period, while in the static mode channel estimation is performed using pilot symbols from the current symbol period and pilot symbols from other symbol periods.

Abstract: In a method for encoding at least two data streams (p1 . . . pn), a bit sequence of each one of the at least two data streams (p1 . . . pn) is mapped onto a symbol in a predefined order which is part of one of at least two subsets (I, II, Ia, Ib, IIa, IIb) of a modulation constellation. The one of at least two subset (I, II, Ia, Ib, IIa, IIb) is determined by an encoding rule that is having regard to the symbols (s1 . . . s16) that already have been used for encoding bit sequences of preceding data streams (p1 . . .

Abstract: Hashes are short summaries or signatures of data files which can be used to identify the file. Hashing multimedia content (audio, video, images) is difficult because the hash of original content and processed (e.g. compressed) content may differ significantly. The disclosed method generates robust hashes for multimedia content, for example, audio clips. The audio clip is divided (12) into successive (preferably overlapping) frames. For each frame, the frequency spectrum is divided (15) into bands. A robust property of each band (e.g. energy) is computed (16) and represented (17) by a respective hash bit. An audio clip is thus represented by a concatenation of binary hash words, one for each frame. To identify a possibly compressed audio signal, a block of hash words derived therefrom is matched by a computer (20) with a large database (21). Such matching strategies are also disclosed.

Abstract: In a lithographic apparatus, a feedforward transfer function of a control system, is determined by: a) iteratively learning a feedforward output signal of the control system by iterative learning control for a given setpoint signal; b) determining a relation between the learned feedforward output signal and the setpoint signal; and c) applying the relation as the feedforward transfer function of the control system. A learned feedforward, which has been learned for one or more specific setpoint signals only, can be adapted to provide a setpoint signal dependent feedforward output signal. The learned feedforward can be made more robust against setpoint variations.

Abstract: Detection means for detecting information in a signal, comprising integration means for integrating the signal over time such that the integration means is periodically reset at about the start time reference of a periodic time interval; and a sample&hold circuit for periodically sampling and holding the integrated signal (int) at about an end time reference of the periodic time interval and thereby delivering a further signal (fs). The detection means further comprises a chain (CHDL) of signal time delay elements, an input of the chain (CHDL) being coupled to receive the further signal (fs); and combining means (CBMNS) having combining inputs coupled to signal taps of the chain (CHDL), such that the number of the combining inputs and the position of coupling the combining inputs to the signal taps of the chain (CHDL) correspond to the information in the signal.

Abstract: A record carrier has a servo track indicating an information track intended for recording information blocks, which servo track has a variation of a physical parameter, referred to as wobble. The wobble is modulated for encoding record carrier information, such as addresses. The servo track is subdivided in non-modulated and parts modulated parts in which the frequency and/or phase of the variation deviates from the wobble frequency. The slope of the wobble is substantially continuous at transitions between the modulated and non-modulated parts by using wobbles starting at the maxima or minima of the wobble.

Abstract: Receivers (1) for receiving encoded block signals and comprising processor systems (2) decode block signals by using Viterbi algorithms for finding a first candidate/path in a trellis (18) and by generating cost signals for finding further candidates/paths in said trellis (18). To reduce storage capacity, cost signals are combined for series of branches and cumulated cost is compared with thresholds. While searching for said further paths, a search for a further path is made in view of cumulated cost exceeding a threshold or not. The insight of indirectly constructing a list of candidates and the basic idea of more directly constructing said list brings more control. These receivers are less complex, and are further improved by introducing increasing thresholds per trellis and successive combining and different trellis directions for generating and cumulating cost signals and combining in a lexicographical order, and using a check sum for list reduction and by making error detections.

Abstract: A method of decoding possibly mutilated code words (r) of a code (C) includes decoding the differences (D) of a number (L?1) of pairs of possibly mutilated code words (rib, ri+1) to obtain estimates (u, v) for the differences of the corresponding pairs of code words (ci, ci+1), combining the estimates (u, v) to obtain a number (L) of at least two corrupted versions (wj) of a particular code word (c), forming a code vector (z) from the number (L) of corrupted versions (wj) of the particular code word (c) in each coordinate, decoding the code vector (z) to a decoded code word (c?) in the code (C), and using the generator matrix (G) to obtain the information word (m) and the address word (a) embedded in the decoded code word (c?).

Abstract: The invention relates to a method of storing a number of data bits of a secondary channel (30) in the frame of a main channel (20) and to a method of decoding a stream of bits relating to a secondary channel (30) embedded in the frames of a main channel (20) into a stream of data bits (62). In order to enable a certain synchronization and to guarantee a fixed amount of storage capacity in the secondary channel as well as to be able to correct deletions or insertions of bits in the secondary channel it is proposed according to the invention to form a secondary frame (11) having a fixed number of frame bits, to fill a fixed part of the secondary frame (11) with data bits (113), an end-bit (114) set to a first bit-value and, if necessary, with filling bits (115) set to a second bit-value, to encode the secondary frame (11) producing encoded data bits (113) and parity bits (112), which are finally embedded in the frame of the main channel (20).

Abstract: A record carrier has a servo track (4) indicating an information track (9) intended for recording information blocks. The servo track (4) has a periodic variation of a physical parameter at a predetermined frequency and modulated parts for encoding position information at regular intervals. The modulated parts start with a bit sync element and are of a data type having a data bit element or of a word sync type having a word sync element. The bit sync element, word sync element and the data bit element being modulated according to a same predetermined type of modulation of the periodic variation. All distances between two adjacent of the elements constituting the modulated parts are unique.

Abstract: A method of selecting a generator matrix (G) for encoding information words (m) including information symbols (m1, m2, mk) into codewords (c) of a code (C) provides an enhanced error correction capability if at least one information symbol (m1, m2, m3) is known a priori to a decoder decoding received, possibly mutilated codewords (r). In order to design a code of which the correction power is enhanced if some information symbols are known to the decoder prior to decoding, the generator matrix (G) is selected such that the minimum Hamming distance of at least one subcode (C?) of the code (C) is larger than the minimum Hamming distance of the code (C), and that a subcode generator matrix (G?) of the at least one subcode (C?) is derived from the generator matrix (G) of the code (C) by omitting the at least one row from the generator matrix (G) corresponding to the at least one a priori known information symbol (m1, m2, m3).

Abstract: The invention relates to method of encoding address words (a) comprising address symbols (a0, a1, . . . ak?1) into codewords (c) of a code (C) for providing an enhanced error correction capability if at least one information symbol (m1) of information words (m) is known a priori to a decoder decoding received, possibly mutilated codewords (r). The invention relates further to a method of decoding possibly mutilated codewords (r).

Abstract: A record carrier (1) is described which has a servo track (4) indicating an information track (9) intended for recording information blocks, which servo track (4) has a variation of a physical parameter, a so called wobble. The wobble is modulated for encoding record carrier information, such as addresses. The servo track is subdivided in modulated parts in which the frequency and/or phase of the variation deviates from the wobble frequency, and non-modulated parts. The slope of the wobble is substantially continuous at transitions between the modulated and non-modulated parts by using wobbles (25,26,27,28) starting at the maxima or minima of the wobble in the first part of the modulated parts.