Showing papers by "Deutsche Telekom published in 1996"

Analysis of OH absorption bands in synthetic silica

Abstract: The presence of bound hydroxyl (SiOH) in silica is well known to produce an optical fundamental absorption band at about 2.7 μm. For optical fiber applications the influence of the corresponding overtones and combination modes on the absorption spectrum are of significant importance. A literature review is presented which reveals uncertainties regarding the correct absorption band intensities as well as their spectral positions. We present precise data on spectral position and relative intensities of OH absorption bands in state of the art synthetic silica. Our investigations cover the influence of different manufacturing techniques, OH content, and a comparison of bulk and fiber data. With the knowledge of the conversion factors between the intensities of different OH absorption bands it is possible to predict the entire OH related transmission performance of an optical component by measurement of a single absorption band, e.g., the fundamental mode at 2.7 μm or the 1.38 μm band in the low loss range of optical fibers.

Adaptive OFDM for wideband radio channels

Abstract: An OFDM (orthogonal frequency division multiplexing) transmission system is simulated with time-variant transfer functions measured with a wideband channel sounder. The individual subcarriers are modulated with fixed and adaptive signal alphabets. Furthermore, a frequency-independent as well as the optimum power distribution are used. The simulations show that with adaptive OFDM, the required signal power for an error probability of 10/sup -3/ can be reduced by 5...15 dB compared with fixed OFDM. The fraction of channel capacity which can be achieved with adaptive OFDM depends on the average signal-to-noise ratio and the propagation scenario.

The dependence of EM energy absorption upon human head modeling at 900 MHz

Abstract: The dependence of electromagnetic energy absorption at 900 MHz in the human head on its anatomy and its modeling are investigated for RF-sources operating in the very close proximity of the head. Different numerical head phantoms based on MRI scans of 3 different adults were used with voxel sizes down to 1 mm/sup 3/. Simulations of the absorption were performed by distinguishing the electrical properties of up to 13 tissue types. In addition simulations with modified electric parameters and reduced degrees of complexity were performed. Thus, the phantoms greatly differ from each other in terms of shape, size, and internal anatomy. The numerical results are compared with those of measurements in a multitissue phantom and 2 homogeneous phantoms of different shapes and sizes. The results demonstrate that size and shape are of minor importance, Although local SAR values depend significantly on local inhomogeneities and electric properties, the volume-averaged spatial peak SAR obtained with the homogeneous phantoms only slightly overestimates that of the worst-case exposure in the inhomogeneous phantoms.

A Universal Predictive Equation for the Inelastic Mean Free Pathlengths of X‐ray Photoelectrons and Auger Electrons

Abstract: A new universal inelastic mean free pathlength (IMFP)-predictive equation (the G1 equation) has been formulated for use in the analytical electron spectroscopies XPS and AES which essentially states that the IMFP of an electron traversing matter is inversely proportional to the atomic density. The equation is based on a concept of matter in which the latter consists of clusters of interaction-prone regions (identified with the orbitals of an atom) in an otherwise interaction-free space. The energy dependence and best values for two fitting parameters were obtained from a large set of IMFPs, derived by Tanuma, Powell and Penn (TPP) from published optical data. The G1 equation has been developed to allow the IMFPs to be predicted not only for regular phases of elements and compounds (a common restriction on existing IMFP-predictive equations), but also for any sub- and non-stoichiometric arrangement of atoms found at technological surfaces. Evidence is presented which substantiates the claim of universal applicability of the G1 equation.

Method and system for determining dynamic traffic information

Abstract: Described are a method and system for the determination of dynamic traffic information or traffic events. Relevant data from vehicle-mounted terminals are recorded automatically, by remote interrogation or manually and transmitted directly, together with a location identifier, via a wide-coverage mobile-telephone network, e.g. GSM, to other mobile-telephone subscribers and/or a higher level exchange. In the exchange, the incoming data are processed and fed to selected terminals and/or third parties. In addition, the results of interrogation, e.g. braking behaviour, can be pre-defined by a traffic-control centre and transmitted by radio broadcast or mobile telephone to the terminals of road users in a geographically limited area who can then "observe" the flow of traffic directly and immediately report incoming interrogation results by mobile telephone back to the exchange.

TROLL: a language for object-oriented specification of information systems

Abstract: TROLL is a language particularly suited for the early stages of information system development, when the universe of discourse must be described. In TROLL the descriptions of the static and dynamic aspects of entities are integrated into object descriptions. Sublanguages for data terms, for first-order and temporal assertions, and for processes, are used to describe respectively the static properties, the behavior, and the evolution over time of objects. TROLL organizes system design through object-orientation and the support of abstractions such as classification, specialization, roles, and aggregation. Language features for state interactions and dependencies among components support the composition of the system from smaller modules, as does the facility of defining interfaces on top of object descriptions.

Verfahren und einrichtung zur ermittlung von dynamischen verkehrsinformationen

Abstract: Beschrieben wird ein Verfahren und eine Einrichtung zur Ermittlung von dynamischen Verkehrsinformationen bzw Verkehrsereignissen Dabei werden verkehrsrelevante Daten von Endgeraten im Fahrzeug automatisch, per Fernabfrage oder manuell aufgenommen und zusammen mit einer Ortsinformation uber ein verbreitetes, mobiles Telekommunikationsnetz, zB GSM, direkt an weitere Mobilfunkteilnehmer und/oder eine ubergeordnete Dienstezentrale ubermittelt In der Dienstezentrale werden die eingehenden Daten weiterverarbeitet und an ausgewahlte Endgerate und/oder Dritte weitergegeben Zum anderen konnen von einer Verkehrsleitzentrale auch Abfrageereignisse vordefiniert werden, zB Bremsverhalten, und per Broadcast uber Mobilfunk in regional beschrankte Bereiche an Verkehrsteilnehmer bzw deren Endgerate ubermittelt werden, die dann unmittelbar den Verkehrsflus 'beobachten' und eintretende Abfrageereignisse sofort wieder per Mobilfunk an die Dienstezentrale zuruckmelden

Verfahren und Anordnung zur Verkehrsinformation

Abstract: Beschrieben wird ein Verfahren zur Verkehrsinformation, wobei auf Anfrage und/oder automatisch Daten zwischen einer Zentraleinheit und einer mobilen Teilnehmereinheit ubertragen werden. Weiter wird eine Anordnung zur Verkehrsinformation beschrieben, wobei mindestens eine Zentraleinheit sowie mindestens mehrere mobile Teilnehmereinheiten vorgesehen sind.

Increase in specific absorption rate in human heads arising from implantations

Abstract: The effect of metallic implantations on the absorbed power distribution within a human head is studied numerically using a lossy dielectric sphere containing conducting elements excited by the near field of a dipole antenna.

Process for a vehicle control and information system

Abstract: A process for a vehicle control and information system in which data and traffic-related information are transmitted by means of at least one radio-transmission system between a vehicle and a central unit. A data-processing unit in the central unit and/or a data-processing unit in the vehicle are used to calculate at least one route, and the route data is transmitted by means of the data-transmission system between the vehicle and the central unit. The data-processing unit in the central unit and/or the data-processing unit in the vehicle simulate in real time the motion of the vehicle, the real-time simulation being carried out both in the vehicle-mounted data-processing unit and in the data-processing unit in the central unit using signals which are it transmitted over the radio transmission system. The vehicle position in the real-time simulation of the motion of the vehicle is displayed in the vehicle together with additional information relevant to the traffic.

Antenna device for mobile communication terminals

Abstract: The antenna system includes several antennas (1a-1j) which are attached to or integrated in the housing (2-7) of the mobile telephone. The high frequency power emitted from each antenna is individually controllable. The antennas are pref. formed as planar antennas and the resistance of each antenna is measured by an impedance sensor. The power emitted from each antenna is regulated by an associated damping element. Alternatively, the power may be regulated by associated switch elements. The power is regulated depending on the measured resistance. A control unit is pref. provided to carry out all necessary measuring and control functions.

Photonic crystals built by three-dimensional additive lithography enable integrated optics of high density

Abstract: Photonic crystals were investigated experimentally in a scaled setup with microwaves in the form of 2D arrays of dielectric rods of high permittivity surrounded by air and are reported in the literature. These crystals render perfect mirrors for a band of wavelengths. Having an impurity built into the structure, transmission filters with a specific narrow bandwidth can be generated. The predominant feature of these structures is, that devices of high finesses are obtained with as few as 6 planes of dielectric rods. The grid constant of the rods is 80 nm diameter and micrometers dimensions with a surface roughness below 3 nm. It offers the freedom to taylor the refractive index of the material by selecting precursor materials, deposition conditions, and exposure mode. A scanning electron microscope with VIDAS-beam control system is used for this lithography. A custom designed lithography function allows to control position, dwelltime, and sequence of the pixels. Using a program generated database, which contains all pixel and time information required, 3D structures are generated with the deposition process. The devices are placed with nm precision in waveguide patterns. Macro-controlled construction of arrays of dielectric rods of high aspect ratios is presented, which resemble perfect or imperfect photonic crystals. Using specialized crystals, filters and tunable filters dense devices for routing of light or optical metrology can be fabricated.© (1996) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

Theoretical bit error rate for uncoded and coded data transmission in digital audio broadcasting

Abstract: In this paper we analyze the bit error rate of an OFDM multicarrier transmission system with DQPSK modulation and differential phase detection both for uncoded and convolutionally coded data. Formulas are derived which take into account the influence of the fast Rician fading channel, but they are valid for multipath Rayleigh fading and the additive Gaussian noise channel as well. Theoretical bit error rates are given for system parameters and channel models proposed for digital audio broadcasting (DAB) in Europe. A comparison with results obtained by a DAB software simulation tool (developed by the same authors) shows good agreement and demonstrates the applicability of the derived set of formulas as a powerful tool for DAB network planning.

Ionizing radiation for fabrication of optical waveguides in polymers

Abstract: Ionizing radiation (light ions up to 200 keV and UV radiation with λ Compaction of the irradiated areas leads to diffractive structures. Changes in the chemical structures of the irradiated samples are reported. The physical properties like mode spectra and attenuation were measured. Passive components with fibers coupled to the devices were fabricated.

A statistical simulation model for the directional mobile radio channel and its configuration

Abstract: Currently new base station concepts are under investigation that take advantage of the directionality of the mobile radio channel either by utilizing antenna beam diversity or adaptive array reception techniques. Unfortunately, the Gaussian (wide sense) stationary uncorrelated scattering (GWSSUS) simulation concept which is most wide-spread adopted in fading simulators neglects any directional anisotropy of the propagation mechanism. In this paper a directional channel simulation model is introduced which is an extension to GWSSUS. Due to its relatively low structural complexity, this directional Gaussian scattering (DGS) concept is applicable not only to soft- but also to hardware fading simulators. The most important advantage of the DGS simulator is that it can easily be configured to match the properties of real-world propagation scenarios. This is achieved based on the information available from echo estimation, a method which recently was introduced for configuring statistical GWSSUS channel models directly from the results of wide-band channel sounding.

Photonic highway switches based on ring resonators used as frequency-selective components.

Abstract: A new concept for a highway switch, which can be used to connect different optical wavelength division multiplexing data highways for data exchange, is proposed and the system relevant properties are outlined. For the required add–drop filter elements we used ring resonators. Typical characteristics of channel bandwidth, channel spacing, free spectral range, amplification, and cross-talk behavior of a highway switch with double-cavity ring resonators are basically examined and to some extent compared with solutions that were obtained with standard single-ring resonators. A signal flow chart transformation for evaluating filter transfer functions is presented.

Process for dynamic channel allocation in mobile radio networks

Abstract: The invention concerns a process for dynamic channel allocation in mobile radio networks, wherein priorities which are increased or decreased in dependence on interference occurring in the channel concerned are established for the individual channels. When the propagation conditions are satisfactory, channels with low priority can be allocated. The mean of values dependent on the extent of interference can be formed in order to increase and decrease the priority. In addition, various priority lists can be established for various interference and/or load situations.

Authorised user control method for telecommunications device

Abstract: The control method involves using a memory device associated with the telecommunications device (10). This is used for holding a reference identification, obtained via a detector (30) with a biometric sensor (32), for scanning a body part of the authorised user, such as the finger tip. The reference identification is compared with the digital identification information subsequently provided by the detector, for verifying the identity of the user, before the telecommunications device can be used. The detector unit with biometric senors may use infrared heat detection for constructing body part outlines

Verfahren zur Speicherung oder Übertragung von stereoskopischen Videosignalen

Abstract: Bei einem Verfahren zur Speicherung oder Ubertragung von stereoskopischen Videosignalen, die ein linkes Videosignal und ein rechtes Videosignal enthalten, ist vorgesehen, das das linke und das rechte Videosignal nach einer Vorfilterung unterabgetastet und miteinander nach einem Zeitmultiplexverfahren kombiniert werden, das das kombinierte Signal datenreduzierend codiert und nach der Ubertragung oder Speicherung decodiert wird, das das decodierte kombinierte Signal wieder in ein linkes und ein rechtes Videosignal aufgeteilt wird und das die durch die Unterabtastung verlorenen Abtastwerte durch interpolierte Abtastwerte ersetzt werden. Zur Datenreduktion kommt vorgzugsweise eine Codierung nach dem MPEG-Verfahren in Frage.

Variable-subframe-length speech-coding classes derived from wavelet-transform parameters

Abstract: A method and a device are described for classifying speech on the basis of the wavelet transformation for low-bit-rate speech coding processes. The method and the device permit a more robust classifier of speech signals for signal-matched control of speech coding processes in order to reduce the bit rate without affecting the speech quality or to increase the quality at the same bit rate. The method provides that, after segmenting the speech signal, a wavelet transformation is calculated for each frame, from which a set of parameters is determined with the help of adaptive thresholds. The parameters control a finite-state model, which subdivides the frames into shorter subframes if required, and classifies each subframe into one of several classes typical for speech coding. The speech signal is classified on the basis of the wavelet transformation for each time frame. Thus both a high time resolution (location of pulses) and frequency resolution (good mean values) can be achieved. This method and the classifier are therefore especially well suited for the control and selection of code books in a low-bit-rate speech coder. They also have a low sensitivity to background noise and low complexity.

Method and device for protecting stored data

Abstract: Generic information storage devices (magnetic, optical, biological/organic devices) are well-suited for storing, processing, archiving or transporting large amounts of information; they can, however, only be secured against unauthorized access using cryptographic methods. Undetected physical copying and manipulation of the information remains, however, possible. Disclosed is a process and device for combining non-intelligent generic information storage devices with intelligent storage devices and linking their information. The process compresses the stored data from a generic storage device and counts a signature count of the stored data. An ID is then provided to the stored data from a permanently assigned intelligent programmable memory chip. At least part of the compressed data is encrypted using an asymmetric key and transferred to a memory area of the permanently assigned intelligent programmable memory chip.

Robust classification of speech based on the dyadic wavelet transform with application to CELP coding

Abstract: This paper describes a new algorithm for the classification of telephone-bandwidth speech that is designed for efficient control of bit allocation in low bit-rate speech coders. The algorithm is based on the dyadic wavelet transform (D/sub y/WT) and classifies each unit subframe into one of the three categories background noise/unvoiced, transients/voicing onsets, periodic/voiced. A set of three parameters is derived from the D/sub y/WT coefficients, each giving a decision score that the associated class is active. Taking the history into account, a finite-state model controlled by these parameters computes the classifier's decision. The proposed algorithm is robust to various types of background noise. In comparison with a classifier based on the long-term autocorrelation function, the D/sub y/WT classifier proves to be superior. To evaluate its performance in CELP-type speech coders, a variety of excitation coding schemes with bit rates between 2200 and 4800 bit/s is investigated.

Traffic data acquisition method especially for vehicle

Abstract: The method involves evaluating operation parameters of a mobile radio network. The parameters include information of operating sequences and conditions in the network. Traffic conditions are determined in at least a part of the road system which is covered by the mobile radio network using specific algorithms. Preferably, types of operation outlines are formed which represent characteristic traffic conditions and which are recorded as reference outlines with further parameters which characterise the traffic condition. Current determined operation parameters and current determined parameters characterising the traffic condition are set in relation to the reference outlines. If variations in the reference outline are detected, the road sections with incidents are identified using specific algorithms.

Multiple channel sound transmission method

Abstract: A method wherein an auralization is performed, in that a plurality of spatial pulse responses are incited from various locations in the same room, and are received via a multi-channel receiving apparatus, for example, a directional microphone or a plurality of directional microphones at one location, and are recorded For the reproduction, a multi-channel loudspeaker arrangement of vertically configured loudspeakers and of horizontally configured loudspeakers is used, at least two loudspeakers being required to reproduce sources in one line from point to point that are able to be localized, at least three loudspeakers for reproduction in one plane, and at least four loudspeakers in one room A convolution processing takes place with a plurality of directly received sound signals, conforming at least in number to the spatial pulse responses, so that the convolved signals are locally distributed between the locations of the reproduction loudspeakers or at the boundaries of a binaural signal, when the sound is reproduced via headphones

Note on decoding binary goppa codes

Abstract: The author gives a simple expression for the polynomial y(x) which solves the polynomial equation y(x)/sup 2//spl equiv/t(x) mod G(x), where t(x), y(x) and G(x) are polynomials over the field GF(2/sup m/). The solution of such an equation is a step in the so called Patterson algorithm for decoding binary Goppa codes. The result may also be useful for other applications.

A 10 Gb/s silicon bipolar IC for PRBS testing

Abstract: A 10 Gb/s silicon bipolar IC for pseudorandom binary sequence (PRBS) testing was fabricated and tested. The IC features PRBS generation of the sequences of length 2/sup 15/-1 and 2/sup 23/-1 b up to 10 Gb/s according to CCITT recommendations. Furthermore, the IC is capable of analyzing PRB sequences of the same length and generation polynomials so that a full test of components is possible. In addition, a new PRBS test word synchronization can be provided between two chips for external multiplexing of the sequences up to 40 Gb/s. The IC can be connected to a standard PC, so evaluation of the error test data can be performed in a flexible way. The IC was fabricated with the HP25 process of Hewlett Packard company, the chip size is 32 mm/sup 2/, and it consumes 6.2 W at the nominal supply voltage of -5 V.

Method for generating and distributing unpersonalised and confidential electronic keys

Abstract: Key carriers are generated by an appropriate authority in a secure environment and personalized and included secret and producer seal. You should be able to be produced in unlimited number in advance and distributed without the certificates in the personalization to write with the mystery together in one key carrier and without the identity of the owner or later use known or defined. The key handles with a visible reference identification, a manufacturer's PIN and a key pre-produced one kept secret component in the especially protected area, and a generator seal and a reference information in the less protected area contains. The fixed associated public key component is stored with a second unequal reference information at the output instance. Only when assigning the key to a user changes the manufacturer PIN in an individual PIN and has its identity to the personalization instance from which manages both references, personalized public key component, sealed, enters into the key directory and confirms the user. The key produced by this process are universally applicable.

Efficient spot-size transformation using spatially separated tapered InP/InGaAsP twin waveguides

Abstract: A tapered twin waveguide structure for low-loss chip-fiber coupling with a large spatial separation between the waveguides was fabricated, providing better optical properties than conventional taper structures together with relaxed fabrication tolerances. The mode transformation losses and coupling losses for different taper geometries were investigated theoretically and experimentally. For a double taper structure with a length of 280 /spl mu/m for a single taper, the total measured insertion loss between two single-mode fibers at a wavelength of 1550 nm using fiber matched refractive index liquid, however, without any antireflection coating, was 3.2 dB.

Mechanical stabilisation and tuning method for photon crystal filter used in optical fibre communications

Abstract: The method involves filling the hollow spaces in the filter, e.g. which is structured as a photon crystal, with optically transparent material of adjustable refractive index. The filled filter is subjected to an electrical field of variable field strength. The optical characteristics, e.g. the refractive index for transmitted and reflected light in the crystal's hollow chamber, fine tuning of the transmitter amplitude and fine tuning of the light phase shift are adjusted by varying the field strength of the electric field.