U.S. Philips Corporation

Other

Alphons A Bruekers

Jozef L Kessels

Renatus Josephus Van Der Vleuten

Raymond N Veldhuis

Gerardus C Gielis

Petrus A Nuijten

Arnoldus W Oomen

Geert F Depovere

Yves F Dehery

Jean Y Roudaut

Johan R Brandsma

Jean B Rault

Method of embedding watermarks in a signal encoded by an encoder having a feedback loop, for example, a sigma-delta modulator (21,22,23). A digital watermark pattern (w) is embedded in the signal (z) by modifying selected samples (for example, replacing every 100th bit) of the encoded signal (y) by samples of the watermark pattern. The circuit (24) for modifying the samples is located inside the loop of the encoder. The effect of watermarking is thus compensated in subsequent encoding steps and the signal-to-noise ratio is only slightly affected.

Embedding supplemental data in an encoded signal, such as audio / video

The invention relates to the coding of digital information signal blocks comprising representation symbols, such as sampled values, by means of an adaptive variable-length coding, such as Huffman coding. The JPEG Standard also utilizes adaptive Huffman coding but the coding in accordance with this standard is inefficient when a comparatively large number of Huffman coding tables are to be transmitted. According to the invention, in the case of a small number of representation symbols per information signal block, the probabilities of occurrence of each of the representation symbols are transmitted together with the variable-length-coded representation symbols, a similar (de)coding table being generated both in the encoder and in the decoder on the basis of said probabilities. In the case of a larger number of representation symbols per information signal block information about the number of code words of each length and/or the maximum code length in each series of variable-length-coded representation symbols is added to this series. By means of this information the decoder can unambiguously generate a coding table. The invention provides a substantial reduction of the number of bits required for specifying the Huffman code tables.

Method of and device for coding a digital information signal

Data compression/expansion using a rice encoder/decoder

A disc-shaped information carrier with a substrate and an information layer which includes optically readable elementary marks having a substantially uniform density. The information layer includes a first portion suitable for being read out at a first read-out speed and a second portion suitable for being read out at a second read-out speed higher than the first read-out speed. According to the invention, the second portion of the information layer is at a greater distance to a center of the disc-shaped information carrier than is the first portion of the information layer. A range of rotational speeds which an optical read-out unit must have for a full and correct read-out of the information carrier is reduced in this manner. In a special embodiment, the first portion of the information layer includes a first version of an audio recording provided on the information layer by the DSD transformation method, whereas the second portion of the information layer includes a second version of this same audio recording provided on the information layer by the PCM transformation method.

Disc-shaped information carrier provided with two portions having

In a the receiver, a reception signal is digitized (5) with a relatively high sampling frequency. Analog filters (2, 4) prevent aliasing. The digitized reception signal is applied via a splitter (100) to a quadrature digital signal processor (9, 10, 11, 12). In this processor, a desired carrier is selected and demodulated. The splitter (100) transforms the digitized reception signal in accordance with a first and a second transform function (H.sub.1, H.sub.2) to obtain in-phase and quadrature components (xi, yi), respectively. The sampling frequency is reduced (130, 140) in the splitter. A specific relation between the phase and magnitude of the transform functions (H.sub.1, H.sub.2) prevents aliasing. Such a relation can be achieved with relatively simple digital filters (110, 120).

Receiver with quadrature decimation stage, method of processing digital

A digital transmission system is disclosed having a transmitter (3,6,9) and a receiver (13,16,19) for transmitting a digital signal, such as a digital audio signal, having a given sampling rate F.sub.S. The digital signal is subband coded into M subbands with sampling rate reduction. To that purpose the transmitter includes a first unit (3) for splitting up the digital signal into M signals having a sampling rate F.sub.S /M. These signals are available at the outputs (4.1 to 4.M) of the first unit (3), and are applied to M analysis filters (6.1 to 6.M), each filter (6.m) having one input (5.m) and two outputs (7.ma and 7.mb). The 2M filter outputs are coupled to 2M inputs (8.1 to 8.2M) of a signal processing unit 9 which has M outputs (10.1 to 10M) for supplying the M subband signals (S.sub.1 to S.sub.M). Each filter (6.m) is adapted to apply two different filterings on the signal applied to its input and to supply the two different filtered versions of the input signal to its two outputs. The signal processing unit 9 is adapted to supply output signals on each of the M outputs, an output signal being a combination of at least a number of input signals applied to its 2M inputs. On the receiver side a signal processing is carried out which is largely inverse to the signal processing on the transmitter side, in order to realize a signal at the output (21) that is a nearly perfect reconstruction of the input signal.

Digital transmission system using subband coding of a digital signal

A time switching method and apparatus for exchanging data words from a sequence of time slots in an incoming time-division multiplex frame to any other sequence of time slots an outgoing time-division multiplex frame. A data word in a given time slot s in an incoming frame is stored in a memory at an address A(s) which is equal to the number of time slots D.sub.j in an outgoing frame for which j is less than s and for which D.sub.j exceeds D(s). The data word already in the memory location address A(s) and the data words in addresses higher than that address are each shifted to the next higher address. Data words at memory addresses lower than A(s) are maintained at such addresses.

Method of switching time slots in a TDM-signal and arrangement for

The invention relates to a broad-band, time-division multiplex, token-passing, ring local area network, with which both circuit-switched and packet-switched traffic, namely data, text, picture and speech traffic can be supported. The invention has for its object to provide a method of transmitting digital information in a ring having a comparatively high transmission capacity with which rapid access to the common ring transmission means can be obtained, without however high requirements being imposed on the processing speed of the stations. According to the invention this is in principle achieved by means of a method which guarantees that per time-division multiplex frame only one time slot, which is known to the station, needs to be accessed.

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Eindhoven, Netherlands

Alphons A Bruekers