Marking a digitally encoded video and/or audio signal

An electronic watermarking scheme is proposed that can significantly increase the security of copy protection mechanisms. The watermarking methods works at high level in the hierarchy of the (MPEG) source signal. This ensures that the watermark is easily detectable, but difficult to erase without significant transcoding effort. Such transcoding is considered a difficult and expensive task that may furthermore lead to loss of quality or increase in bit rate

Biological Rhythm Aware Office Lighting Control

We formulate the lighting control system as a mathematical optimization problem which is highly nonlinear and acts of a longer time interval. To this end we introduce an iterative optimization algorithm to achieve a solution. This method can be used to develop scalable human-centric smart lighting control systems centered towards bringing support to the biological rhythm of individual employees. We test the inter-person variability of the optimum light exposure, and concluded that theory predicts that there is no one-size-fits-all light recipe. In particular, individual differences in late-evening light exposure require differentiation in the late afternoon. Humans are different. Our evaluations show that standard deviations in biological difference (intrinsic period) and social behavior require different light recipes. That is, human centric lighting control based on population averages have much less effect, compared to algorithms that take human variation into account. Possible one-size-fits-all human centric lighting is inadequate to achieve the desired impact or may be counterproductive for specific humans.<br/

Biological Rhythm Aware Office Lighting Control

We formulate the lighting control system as a mathematical optimization problem which is highly nonlinear and acts of a longer time interval. To this end we introduce an iterative optimization algorithm to achieve a solution. This method can be used to develop scalable human-centric smart lighting control systems centered towards bringing support to the biological rhythm of individual employees. We test the inter-person variability of the optimum light exposure, and concluded that theory predicts that there is no one-size-fits-all light recipe. In particular, individual differences in late-evening light exposure require differentiation in the late afternoon. Humans are different. Our evaluations show that standard deviations in biological difference (intrinsic period) and social behavior require different light recipes. That is, human centric lighting control based on population averages have much less effect, compared to algorithms that take human variation into account. Possible one-size-fits-all human centric lighting is inadequate to achieve the desired impact or may be counterproductive for specific humans.<br/

Coded beam searching for bi-directional optical wireless communication system

In a communication system with steerable laser beams, the transmitter must find the direction towards the receiver. This requires a feedback loop such that the receiver can signal that the correct direction has been found. However, the receiver may not be able to instantly give high-resolution feedback if the beam hits its detector. At least during the acquisition phase, thus before transmitter and receiver are aligned in both directions, this feedback channel typically has a wider beam and a much lower bandwidth, thus a (possibly random) latency and a lower time resolution. It is often not practical to adaptively widen the optical beam during acquisition, but even if one designs for an adaptive beam width, it is not evident that this accelerates the search as we argue in this paper. The paper also describes a suitable address coding scheme based on maximum-length Linear Feedback Shift Register sequences, that accelerates the search significantly

Run time acceleration for adaptive algorithm for OFDM bit-loading for OWC channels

Effective power and bit loading strategies are indispensable for mitigating throughput losses attributed to the low-pass frequency response of the light emitting diodes (LED)s and photodiodes (PD)s in optical wireless communication (OWC) systems. To enable the widespread adoption of a high-speed wireless technology using LEDs, the development of precise, computation-friendly algorithms is required. Although expressions for the power allocation in a continuous channel exist, these show to not be the most appropriate in real scenarios as the OWC chipsets are digital devices with finite precision. Moreover, response of the transimpedance amplifiers (TIA)s shows to distort the power spectrum density of the noise, a factor often assumed to be flat in existing expressions. In this research, we delve into the adaptation and acceleration of an iterative algorithm in the past used in radio frequency (RF) systems to optimize performance of LED-based OWC systems. The strategy shows to be efficient, less computationally demanding then commonly used optimization solvers and it intrinsically consider the finite precision of the chipsets

Recordable Storage Medium With Protected Data Area

The invention relates to a method of storing data on a rewritable data storage medium, to a corresponding storage medium, to a corresponding recording apparatus and to a corresponding playback apparatus. Copy-protective measures require that on rewritable storage media some data must be stored which shall not be modifiable or erasable by consumer end products. A practical problem is the storage of large quantities of such data in a fixed data area. Typically the capacity is limited to a few bits. Meanwhile the amount of copy protection data that needs to be stored may well exceed the storage capacity available in the read-only fixed data area. The invention therefore proposes to write the copy protection data as system data in the recordable data area (4), e.g. as part of the formatting of the medium (1). A cryptographic summary is computed and also stored in the recordable data area (32) or in the fixed data area (2) such that a cryptographic relationship between the fixed data area (2) and the system data area (3) is provided. A playback or replay apparatus will only accept a storage medium with a valid combination of copy protection data and fixed data

Recordable Storage Medium With Protected Data Area

The invention relates to a method of storing data on a rewritable data storage medium, to a corresponding storage medium, to a corresponding recording apparatus and to a corresponding playback apparatus. Copy-protective measures require that on rewritable storage media some data must be stored which shall not be modifiable or erasable by consumer end products. A practical problem is the storage of large quantities of such data in a fixed data area. Typically the capacity is limited to a few bits. Meanwhile the amount of copy protection data that needs to be stored may well exceed the storage capacity available in the read-only fixed data area. The invention therefore proposes to write the copy protection data as system data in the recordable data area (4), e.g. as part of the formatting of the medium (1). A cryptographic summary is computed and also stored in the recordable data area (32) or in the fixed data area (2) such that a cryptographic relationship between the fixed data area (2) and the system data area (3) is provided. A playback or replay apparatus will only accept a storage medium with a valid combination of copy protection data and fixed data