Patents Assigned to Koninklijke PTT Nederland N.V.
  • Patent number: 5581546
    Abstract: Apparatus for monitoring a flow of ATM cells in which a measured value is calculated in all cases. A `leaky bucket` mechanism known for this purpose has too few degrees of freedom to be able to monitor the flow of cells accurately enough for it to be possible to deduce from cell flow variations whether a (temporary) cell rate increase is the consequence of an unavoidable variation induced by the transmission system or of an unduly high cell rate (which is in fact avoidable) on the part of the system users. The operation of the apparatus can be adjusted better to the cell flow characteristics if the measured value (CV.sub.n) is a function of a previously calculated reference arrival time (RAT.sub.n) and the actual arrival time (AT.sub.n) of the arriving cell. The reference arrival time is, in turn, a function of the reference arrival times (RAT.sub.n-p, RAT.sub.n-q, . . . ) of one or more preceding cells (n-p, n-q, . . . ) and of the actual arrival times (AT.sub.n-p, AT.sub.n-q, . . .
    Type: Grant
    Filed: February 14, 1995
    Date of Patent: December 3, 1996
    Assignee: Koninklijke PTT Nederland N.V.
    Inventors: Andre H. Roosma, Jacob C. Van Der Wal, Wilhelmina M. Ten Wolde
  • Patent number: 5574808
    Abstract: An integrated optical switching device for switchably converting a fraction of a first guided mode signal into a second guided mode signal of different order is provided. Added to a passive mode converter (c) provided with a bimodal waveguide, in which the conversion can take place by a periodic coupling in coupling surfaces 1-N as a consequence of a specific geometry (f, g), are electrodes (10, 14) for switchably disrupting the coupling, as a consequence of which the conversion does or does not take place. Preferably, the optical switching device is constructed on semiconductor material and the modification is carried out by charge carrier injection. On/off and directional switches based on this are provided. As a result, the advantages of the present system are very good integrability, short length, no critical parameters in the manufacture, and operation at low control currents.
    Type: Grant
    Filed: September 12, 1994
    Date of Patent: November 12, 1996
    Assignee: Koninklijke PTT Nederland N.V.
    Inventor: Johannes J. G. M. van der Tol
  • Patent number: 5574929
    Abstract: Personal computers, a first processor and a second processor belonging to a processor circuit such as a PC card, communicate with one another via a quasi dual-port RAM. The first processor and the second processor alternately read data out of the RAM and write other data into the RAM. Furthermore, the second processor communicates directly with an associated peripheral device. By offering the possibility of, in a first mode, communication between the first processor and the RAM, and communication among the second processor, the peripheral device and the RAM and, in a second mode, communication between the first processor and the peripheral device without using the RAM and without the intervention of the second processor, the PC card becomes sufficient for test purposes and permits backup possibilities. By storing a synchronization protocol into the first processor and into the second processor, the first processor and the second processor can be easily synchronized with each other.
    Type: Grant
    Filed: June 3, 1994
    Date of Patent: November 12, 1996
    Assignee: Koninklijke PTT Nederland N.V.
    Inventors: Rob Pieterse, Wing K. Cheung, Dirk J. J. Van Bruchem
  • Patent number: 5570217
    Abstract: In a branched optical fibre network in which an optical signal (I) modulated with a data signal is distributed by a transmitter connected to the network, OTDR based on correlation is applied independently of position by uncoupling both a signal part (I.sub.1) of the distributed signal (I) in the forward direction and a signal part (R.sub.1) of the reflected signal (R) in the return direction at an arbitrarily chosen uncoupling point P in a fibre connection (46) of the network, detecting them and correlating them with one another. A device for performing such a positionally independent correlation OTDR is provided with uncoupling means (60) having a first signal output (68) and a second signal output (66), via which outputs the signal part (I.sub.1) and the signal part (R.sub.1), respectively, are fed to optical receivers (70 and 71).
    Type: Grant
    Filed: October 28, 1994
    Date of Patent: October 29, 1996
    Assignee: Koninklijke PTT Nederland N.V.
    Inventor: Franciscus H. Fleuren
  • Patent number: 5561700
    Abstract: A device, for digitally measuring in real-time analog telephony signals appearing on a subscriber line during a telephone call thereover, having a converter for converting analog subscriber line voltages into corresponding digital samples, a memory for storing a number of these samples and a processor which resides in any one of various states. For each such state, the processor generates at least one different mask condition, the condition being a limit value of a pre-defined characteristic of at least a particular one of the stored digital samples relative to other such samples. The processor occupies various states with the selection of any one of these states depending upon a particular previous and/or subsequent history of the line voltages with respect to that call, i.e. the state of the call. The processor checks whether some of the stored digital samples satisfies the mask condition.
    Type: Grant
    Filed: June 16, 1994
    Date of Patent: October 1, 1996
    Assignee: Koninklijke PTT Nederland N.V.
    Inventor: Lodewijk M. Van Breda
  • Patent number: 5560031
    Abstract: Processor circuit having two communication paths suitable for modem applications is described. The card includes a receiving/transmitting (R/T) circuit and a first processor. The R/T circuit is coupled to a second processor, e.g., the processor of a personal computer. It is also coupled to a network via the first processor. Data to and from the network is routed by the first processor to the second processor via the R/T circuit. A dual access memory device is also used to couple the first and second processors together. Use of the dual access memory device simplifies error diagnosis and the passing of error information between the first and second processors. A new main program is placed in a RAM of the first processor without the need for an expensive emulator or use of an EEPROM through the use of the dual access memory device. By storing an auxiliary program, e.g.
    Type: Grant
    Filed: June 22, 1994
    Date of Patent: September 24, 1996
    Assignee: Koninklijke PTT Nederland N.V.
    Inventors: Franciscus A. G. Vankan, Rob Pieterse
  • Patent number: 5557318
    Abstract: Method and apparatus for providing a receiver a high quality video signal and a plurality of lower quality video signals which can be zapped, i.e., searched through at any given time, via a channel having a limited data capacity. A first set of high quality video signals is present at a transmitter, e.g., fifty programs having a 10 Mbit/s data rate. A second set of video signals which is a subset of the first set of video signals is sent to the receiver in response to a control signal which indicates the programs a viewer has selected to be viewed at high quality, e.g., using the full 10 Mbit/s of data. A third set of video signals is also sent from the transmitter to the receiver. This third set of video signals represents low quality programs, e.g., signals having a 1 Mbit/s data rate, which can be searched.
    Type: Grant
    Filed: July 7, 1995
    Date of Patent: September 17, 1996
    Assignee: Koninklijke PTT Nederland N.V.
    Inventor: Christiaan M. W. Gabri el
  • Patent number: 5544266
    Abstract: Known transcoders for compressed video signals comprise a decoder and a coder coupled thereto, between which a data signal is transmitted. Because compressed video signals comprise so-called difference pictures and normal pictures, both the decoder and the coder should have a feedback loop which is utilized in decoding and coding a difference picture and is not utilized in decoding and coding a normal picture. For example, for the purpose of prediction means (motion compensation and motion estimation) present in the feedback loop of the coder, much computation has to be carried out in the coder. The computation required is considerably reduced by concomitantly transmitting one or more information signals in addition to the data signal in a transcoder according to the invention, and complete decoding and complete coding no longer takes place.
    Type: Grant
    Filed: July 19, 1994
    Date of Patent: August 6, 1996
    Assignee: Koninklijke Ptt Nederland N.V.
    Inventors: Johannes F. A. Koppelmans, Arian Koster, Dolf A. Schinkel
  • Patent number: 5539845
    Abstract: Integrated optical polarization converter provided with a channel-type waveguide (B) defined by a strip-type structure (S.sub.4) supported by a substrate (S) and having a periodic concatenation of two different part strips having side walls which are at different angles with the plane of the substrate. The two part strips have as cross-sections either a trapezium (EFGH with .DELTA..sub.1, .DELTA..sub.2 .noteq.0) and a rectangle (EFGH with .DELTA..sub.1 =.DELTA..sub.2 =0), or both of them a right-angled trapezium with oblique sides situated opposite one another (EFGH with .DELTA..sub.1 0 and .DELTA..sub.2 .noteq.0, and EFGH with .DELTA..sub.1 .noteq.0 and .DELTA..sub.2 =0). Oblique and vertical side walls on such a strip-type structure supported by a substrate are fabricated, in the case of suitable crystal orientation, by means of two mutually complementary mask patterns, using etching steps, employing wet-chemical and dry etchants respectively.
    Type: Grant
    Filed: June 7, 1995
    Date of Patent: July 23, 1996
    Assignee: Koninklijke PTT Nederland N.V.
    Inventor: Johannes J. G. M. van der Tol
  • Patent number: 5539802
    Abstract: Test system for testing a telecommunication system (1) for reliability of the usage billing. A number of simulation units (8) is connected via normal subscriber lines (7). Each includes a control unit (9) which is controlled by a control program (13) with a number of program steps (1 . . . n). Each of these includes a start code (S1 . . . Sn). A program step is executed after the control unit detects a start code signal (SCS) which is identical to the start code valid for that program step. Simultaneously, the corresponding program steps in the other simulation units are executed, which simulates the simultaneous behavior of different subscribers. In all the simulation units, the start code signals and the various start codes are identical to one another. Preferably, the program start codes and the start code signal comprise a time code. The start code signal can be an externally generated radio signal, such as the DCF77 radio time signal.
    Type: Grant
    Filed: December 20, 1993
    Date of Patent: July 23, 1996
    Assignee: Koninklijke Ptt Nederland N. V.
    Inventors: Iwar De Caluwe, Mark A. Hensbergen, Gregorius B. Huitema, Jaap Kleerebezem, Geert J. Meijer, Kornelis E. Pol
  • Patent number: 5528708
    Abstract: An alignment-tolerant fabrication of a waveguide structure having a symmetrical component structure and an asymmetrical component structure such as an asymmetrical X junction, with the aid of the technique of double masking is presented. The entire waveguide structure is defined by two different mask patterns (p.sub.1, p.sub.2) which are applied successively and in a mutually overlapping position. The two mask patterns are aligned with respect to one another according to alignment directions parallel (z-axis) and perpendicular (x-axis) to the axis of symmetry of the symmetrical component structure. Each mask pattern comprises a first asymmetrical component pattern (32;35) and a second asymmetrical component pattern (31,33; 34,36). The first component patterns (32 and 35) each define a separate portion of the asymmetrical component structure.
    Type: Grant
    Filed: February 14, 1995
    Date of Patent: June 18, 1996
    Assignee: Koninklijke PTT Nederland N.V.
    Inventor: Johannes J. G. M. Van Der Tol
  • Patent number: 5528629
    Abstract: Speech signals coded according to the principle of high-resolution long-term prediction (HLTP) have a high accuracy due to the high-resolution which causes a high complexity. The ordinary LTP method is improved by use of oversampling and determining subsegments Cd lying in a preceding segment which precedes a subsegment to be coded, for which it is the case that the number of samples Dd, expressed in the numbers of samples after oversampling, between the initial time instant of the subsegment to be coded and the initial time instant of a subsegment Cd, fulfills the relation Dd=(D*Ob)/d, in which d=2,3,4 . . . n, where n is a positive integer and where Ob and n are chosen in a manner such that Dd is always an integer. Null sample values produced initially for oversampling are given significance by means of an interpolation technique, at predetermined positions which are situated at a spacing Dd from the original samples in the subsegment to be coded.
    Type: Grant
    Filed: March 2, 1995
    Date of Patent: June 18, 1996
    Assignee: Koninklijke PTT Nederland N.V.
    Inventors: Adrianus A. M. van der Krogt, Robertus L. A. van Ravesteiin
  • Patent number: 5524156
    Abstract: An optical waveguide circuit comprises a mode splitter and an input guide (1/4/6.1) and first and second output guides (6.2/2, 6.3/3), and a mode converter (5) incorporated in the input guide for converting a fraction of an optical signal (I.sub.i), entering via the input waveguide, of a first propagation mode into a second propagation mode having mutually different order. The mode converter (5) has a first waveguiding section (5.1) and a second waveguiding section (5.2), which adjoin each other via a single discontinuity (7). The first and second sections (5.1 and 5.2) have propagation modalities, as a result of which, at the discontinuity, a coupling can take place between two propagation modes of different order, whereas the extent (x) of discontinuity determines the fraction of conversion for obtaining a desired splitting ratio in emitting signals (I.sub.o1, I.sub.o2).
    Type: Grant
    Filed: May 31, 1995
    Date of Patent: June 4, 1996
    Assignee: Koninklijke PTT Nederland N.V.
    Inventor: Johannes J. G. M. Van Der Tol
  • Patent number: 5510787
    Abstract: Known systems based on layered coding and decoding do not take account of the greater surface area of an HDTV picture, which is to be coded with high resolution, compared with the smaller surface area of a conventional picture, to be derived therefrom, which is to be coded with low resolution. An improvement in the efficiency of the coding and decoding is achieved by actually taking account of this with the system according to the invention and maintaining the coupling between the two layers in the encoder and the decoder if a picture element is situated in a corresponding section of the two pictures and interrupting the coupling if a picture element is situated outside the corresponding section of the two pictures.
    Type: Grant
    Filed: September 10, 1993
    Date of Patent: April 23, 1996
    Assignee: Koninklijke PTT Nederland N.V.
    Inventor: Arian Koster
  • Patent number: 5500757
    Abstract: Optical receiving system, incoming unipolar pulses being converted into bipolar pulses having a constant top amplitude (elements 2, 3 and 4) which, on the one hand, are used for generating replicas of the original pulses, but having a constant top amplitude (element 5) and, on the other hand, for eliminating mutual phase differences by means of phase comparison with local clock pulses (elements 7..14). The latter is preferably effected by the bipolar pulses being multiplied (element 7) by the clock pulses, and by using the resulting DC signal to control a controllable delay element (8).
    Type: Grant
    Filed: May 31, 1994
    Date of Patent: March 19, 1996
    Assignee: Koninklijke PTT Nederland N.V.
    Inventor: Cornelis M. De Blok
  • Patent number: 5497368
    Abstract: A method and apparatus for selecting routes in a hierarchical communications network wherein a number of mutually isolated areas are provided at a first level, which areas are mutually linked at a second level. In the network, routing devices are provided at both levels. For selecting a route from a first area to a second area, use is made of routing information stored in the routing devices of the first level, relating to the first level and to reaching the nearest routing device of the second level. Use is also made, in the routing devices of the first level, of routing information relating to the second level.
    Type: Grant
    Filed: August 15, 1994
    Date of Patent: March 5, 1996
    Assignee: Koninklijke PTT Nederland N.V.
    Inventors: Adrianus A. L. Reijnierse, Daan D. Velthausz
  • Patent number: 5491763
    Abstract: In known coherent optical receivers comprising two detectors, optical 90.degree. hybrids have a `throughput` .ltoreq.25%. Theoretical analysis reveals that a higher `throughput` of up to a maximum of approximately 29.3% is possible. The invention provides such a 90.degree. hybrid (30) of the coupler type with the aid of a 2.times.2 port which is based on a loss-free 3.times.3 directional coupler having the maximum throughput ratios between two of the inputs (31/39, 32/40) and two of the outputs (39/34, 40/35) and the 90.degree. phase difference between said two outputs, the third input and the third output not being used. An integrated version employing indium phosphide is described.
    Type: Grant
    Filed: May 13, 1993
    Date of Patent: February 13, 1996
    Assignee: Koninklijke PTT Nederland N.V.
    Inventors: Mattijs O. van Deventer, Johannes J. G. M. van Der Tol
  • Patent number: 5485461
    Abstract: Method for detecting data packets, such as ATM data cells. The preamble comprises a bit alignment word (AW) and a unique word (UW). Successively, the Hamming distances, hd's, are calculated from the first detected l-bit, over a length of AW plus UW, then from the next bit over a length of UW, and finally from the second 1-bit, again over a length of AW plus UW. The position of the first bit of the detected data packet is then calculated on the basis of the hd values thus calculated.
    Type: Grant
    Filed: June 23, 1994
    Date of Patent: January 16, 1996
    Assignee: Koninklijke PTT Nederland N.V.
    Inventor: Hamidreza Asgari
  • Patent number: 5479492
    Abstract: Televoting method in which a large number of subscribers (1) connected to a telecommunications network (2) are able to make a call to a subscriber number, referred to as televoting number, of a televoting processor (4) in order then to transmit their vote to said processor. At the calling subscribers' end, the probability of transmission of calls intended for the televoting number are deliberately reduced substantially in a random manner, either directly by `balloting` or indirectly by random time delay. The system for carrying out this method comprises televoting devices (3) at the subscribers' (1) end, said subscribers having a balloting device which substantially reduces the probability of transmission of calls intended for the televoting number and/or a delaying device which postpones the transmission of calls intended for the televoting number by an arbitrary length of time. The system is intended to prevent an explosion of calls to the televoting processor in televoting, for example in TV programs.
    Type: Grant
    Filed: December 1, 1993
    Date of Patent: December 26, 1995
    Assignee: Koninklijke PTT Nederland N.V.
    Inventors: Jan H. E. Hofstee, Petrus W. M. A. Hoogstraten, Ad D. Kruif
  • Patent number: 5474277
    Abstract: A partially leaky pulling plug (10) coupled to the foremost end (8) of a cable (4) which is to be pulled through a tubular cable conduit (6) with the aid of drag forces of a flowing medium, is provided with a suitably dimensioned flow opening (12) for allowing the flow-through of the flowing medium in a manner not reducing the drag forces considerably, however with a certain pressure difference (Px-Px') across the plug (10). This pressure difference imparts thrust to the plug. The thrust of the plug exerts additional tensile forces on the foremost end (8) of the cable. Preferably the plug has a circumferential suction seal with the inside wall (11) of the conduit (6), and the flow opening is dimensioned such that during installation the flow velocity in the flow opening is essentially equal to that of sound in the flowing medium. The flow opening (12) may be fixedly chosen or may vary in a pressure-dependent manner.
    Type: Grant
    Filed: May 24, 1994
    Date of Patent: December 12, 1995
    Assignee: Koninklijke PTT Nederland N.V.
    Inventor: Willem Griffioen