Patents by Inventor Rolf Heidemann

Rolf Heidemann has filed for patents to protect the following inventions. This listing includes patent applications that are pending as well as patents that have already been granted by the United States Patent and Trademark Office (USPTO).

  • Patent number: 6026116
    Abstract: Stationary interference signals from radio stations, for example, enter a transmission network (NET), e.g., a coaxial cable network with return channel, and impair the transmission of broadband signals, e.g., data, in the upstream frequency band, since they lie in the same frequency range. The transmitting/receiving unit (SE1) of a terminal (END) contains a receiving unit (EMP1) for receiving frequency values of stationary interference signals induced in the transmission link, a memory (MEMO1) for storing the received frequency values, a generator (SG1, NG1) for generating a spreading function with spectral zeros at frequency values which are determined from the stored frequency values, and a multiplier (MUL1) for multiplying the broadband signals to be transmitted by the generated spreading function with spectral zeros.
    Type: Grant
    Filed: November 26, 1997
    Date of Patent: February 15, 2000
    Assignee: Alcatel
    Inventors: Rolf Heidemann, Heinz Krimmel
  • Patent number: 5748348
    Abstract: In an optical communication system in which cable-television signals and subscriber-assigned tele-communication signals are transmitted over a passive optical network (4, 5) to at least one optical network termination (6), each optical network termination (6) requires two optical-to-electrical transducers. An optical network termination (6) is disclosed which requires only one optical-to-electrical transducer (24). The system has two transmitting devices (1, 2) which each transmit a respective optical signal (O.sub.TV, O.sub.D). In the second transmitting device (2), a second electric signal (S.sub.D), whose energy occupies a second frequency band (FB2), is processed in such a way that the energy is concentrated in a subband lying outside the first frequency band (FB1) of a first electric signal (S.sub.TV). The optical-to-electrical transducer (24) in the optical network termination (6) converts the received optical signals (O.sub.TV, O.sub.D) to an electric multiplex signal (E.sub.
    Type: Grant
    Filed: November 6, 1995
    Date of Patent: May 5, 1998
    Assignee: Alcatel N.V.
    Inventors: Rolf Heidemann, Gustav Veith, Jurgen Otterbach
  • Patent number: 5719874
    Abstract: In known optical distribution systems, a signal intended for the subscribers is distributed from a transmitting point to all network terminations (point-to-multipoint transmission). The receivers, which are connected to a passive optical network, are adapted to a common bit rate. If a need for a higher data rate arises at a network termination, this need can only be satisfied in the prior art by converting all receivers. This is not possible without interrupting the service. Furthermore, the conversion entails great expense, since the receivers of these network terminations where the need for information is unchanged have to be converted as well. By a time-division-multiplexing method, a time-division multiplex signal is generated which has a frame whose duration is equal to one bit period (T) of a digital signal, and which is divided into k time slots (ZS). At least two time slots (ZS) are used for one digital signal, and one respective time slot (ZS) is used for each of the remaining digital signals.
    Type: Grant
    Filed: October 19, 1995
    Date of Patent: February 17, 1998
    Assignee: Alcatel Sel A.G.
    Inventors: Rolf Heidemann, Heinz Krimmel, Jurgen Otterbach
  • Patent number: 5631760
    Abstract: The invention relates to a heterodyne receiver, preferably for multichannel reception, especially for the reception of optical signals, in which the received signal is mixed with an oscillator signal of an oscillator in a mixing stage, to generate an intermediate frequency in an intermediate frequency stage (IF stage). According to the invention, the frequency (f.sub.LO) of the oscillator is tuneable discontinuously in jumps (Sp1, Sp2), and the intermediate frequency stage is tuneable continuously.
    Type: Grant
    Filed: November 15, 1991
    Date of Patent: May 20, 1997
    Assignee: Alcatel N.V.
    Inventor: Rolf Heidemann
  • Patent number: 5550667
    Abstract: A laser (2) of an optical transmitter (1) for the transmission of an analog broadband signal for CATV in particular, can be amplitude-modulated in two different manners with an intelligence signal (N). Direct modulation can lead to an undesired additional frequency modulation. With indirect modulation by means of an optical intensity modulator (3), Brillouin scattering occurs at powers of approximately 10 mW in an optical fiber of the transmission path connected to the optical transmitter (1). Both modulations lead to distortions of the transmitted signal. In order to avoid the disadvantages of both modulations in a technically simple fashion, the carrier emitted from a laser (2) is indirectly modulated with an intelligence signal (N) and the laser (2) also faintly directly modulated with an energy-dispersing signal (V).
    Type: Grant
    Filed: August 18, 1993
    Date of Patent: August 27, 1996
    Assignee: Alcatel N.V.
    Inventors: Heinz Krimmel, Henning Bulow, Rolf Heidemann, Jurgen Otterbach
  • Patent number: 5521752
    Abstract: The input light in fiber-optic amplifiers is monitored in order to turn off the system in which it is contained, or individual components of the system, e.g. the fiber-optic amplifier itself, when input light is lacking. To that effect, in known fiber-optic amplifiers, a portion of the input light is coupled out by a coupler. However, this coupler has disadvantages; e.g. the signal-to-noise ratio deteriorates. To monitor the input light, the fiber-optic amplifier of the present invention uses a device (4), which couples out and evaluates the pump light that was not absorbed by the section of the optical waveguide (2).
    Type: Grant
    Filed: March 24, 1994
    Date of Patent: May 28, 1996
    Assignee: Alcatel N.V.
    Inventors: Rolf Heidemann, Bernhard Junginger
  • Patent number: 5517232
    Abstract: It is desirable to offer the subscribers of a cable television distribution network, in addition to the cable TV service, a video-on-demand service. Since, in the foreseeable future, the fiber-optic portion of the cable television distribution networks will not extend to the subscribers (111) but will terminate in optical network terminations (ONT.sub.i) from which a respective optical access network (108-110) will extend to the subscribers, the problem arises how to transmit the entirety of subscriber-assigned video signals to the subscribers so that the latter can receive the requested video signals. According to the invention, the transmission from the center (100) through the fiber-optic distribution network (101-107) to the optical network terminations (ONT.sub.i) is digital, using time- and wavelength-division multiplexing.
    Type: Grant
    Filed: July 7, 1994
    Date of Patent: May 14, 1996
    Assignee: Alcatel SEL Aktiengesellschaft
    Inventors: Rolf Heidemann, Heinz Krimmel
  • Patent number: 5499135
    Abstract: Known optical amplifiers, which are used in a light transmission path to amplify the light signals to be transmitted, have the disadvantage that the semiconductor lasers, used as pump lasers therein, are very sensitive to feedback.According to the invention, the operating current of such pump lasers (4) is modulated at a high frequency, which causes the pump laser to operate in a multi-mode, thereby making it insensitive to feedback. For example, the operating current is DC, on which AC is superimposed.In the event the optical amplifier has two pump lasers, their operating current is also modulated. Both pump lasers are then advantageously alternately switched on and off at a sufficiently high switching frequency, which also prevents reciprocal interference.
    Type: Grant
    Filed: October 14, 1994
    Date of Patent: March 12, 1996
    Assignees: Alcatel N.V.
    Inventors: Rolf Heidemann, Thomas Pfeiffer, Manfred Kaiser
  • Patent number: 5475521
    Abstract: If, in optical communication systems using fiber-optic amplifiers, the optical isolator at the input is omitted on cost grounds and because of the deterioration of the noise characteristics caused by the insertion loss, a giant pulse may be developed when a fiber-optic connector at the input is being separated. To avoid this occurrence, use is made of a monitoring device (7) which, when the power input to the fiber-optic amplifier (4, 5, 3, 6) drops below a given threshold, quickly turns off the current of the pump laser (4) or interrupts the light path of the pump laser (4).
    Type: Grant
    Filed: May 6, 1993
    Date of Patent: December 12, 1995
    Assignee: Alcatel SEL Aktiengesellschaft
    Inventor: Rolf Heidemann
  • Patent number: 5473286
    Abstract: A microwave generator has its microwave frequency optically phase-locked by means of a reference frequency of a reference signal, wherein at least one portion of an electronic circuit arrangement is supplied with an optical reference carrier signal modulated with the reference frequency. The circuit arrangement (16) includes two components (Q1 to Q6; Q10, Q11) based on different semiconductor types which are chosen so that one of them, the first component, which is of a first semiconductor type, optically responds to the reference carrier signal (3) and, thus, to the reference frequency (f.sub.1 Mod1. . . Modn) for achieving synchronization, and that--independently of the response of the first component--the other, second component, which is of a second semiconductor type, responds to an optical control carrier signal (6) differing in frequency from the reference carrier signal (3).
    Type: Grant
    Filed: February 18, 1994
    Date of Patent: December 5, 1995
    Assignee: Alcatel N.V.
    Inventor: Rolf Heidemann
  • Patent number: 5453872
    Abstract: An optical system includes a fiber-optic amplifier having a section of optical waveguide doped with a rare-earth element and a pump-light source for emitting pump light, the fiber-optic amplifier receiving signal light of a first wavelength and outputting at least signal light of a second wavelength. An optical-to-electrical transducer receives the signal light of the second wavelength from the fiber-optic amplifier and produces an electrical output signal. The signal light of the second wavelength is pump light which is unabsorbed in the section of optical waveguide.
    Type: Grant
    Filed: July 26, 1994
    Date of Patent: September 26, 1995
    Assignee: Alcatel N.V.
    Inventors: Rolf Heidemann, Henning Bulow, Thomas Pfeiffer
  • Patent number: 5412746
    Abstract: A coupler (1) made of optical fibers is provided with a device for detecting the light that is carried in one of the fibers at the coupler output in operation. For that purpose, the coupler (1) embedded in an enclosure (2) has at the coupler output a lens body (8) enclosing the optical fiber (pigtail 6) and a detector (9) aimed at the lens body (8). With the detector, during coupler operation, lost light dissipated via the primary coating of the optical fiber is received by the lens body (8 ) and carried by the detector (9) to an electrical evaluator.
    Type: Grant
    Filed: March 22, 1994
    Date of Patent: May 2, 1995
    Assignee: Alcatel N.V.
    Inventors: Rolf Rossberg, Rainer Fritschi, Jurgen Otterbach, Rolf Heidemann
  • Patent number: 5378937
    Abstract: To compensate for nonlinear signal distortions in analog optical communication transmission systems, caused by laser chirps and the chromatic dispersion of the optical fiber, an equalizer in the form of an LC component is known, whose capacitance is formed by a variable capacitance diode. However, the known equalizer functions only when the capacitance has the proper polarity, which cannot be predicted because of possible polarity inversion during signal transmission. According to the invention, the variable capacitance diode (C.sub.a) has another variable capacitance diode (C.sub.b), with the opposite polarity, connected in parallel, and is equally biased in the high-resistance direction. By adjusting the bias voltage of both capacitances, it can be achieved that one of the two variable capacitance diodes takes over the equalization function, and the other is practically inoperative.
    Type: Grant
    Filed: June 29, 1992
    Date of Patent: January 3, 1995
    Assignee: Alcatel N.V.
    Inventors: Rolf Heidemann, Heinz Krimmel, Bernhard Junginger
  • Patent number: 5363385
    Abstract: A fiber-optic amplifier for use with optical communications systems includes a light waveguide piece for amplifying an optical input signal. A pump light source is coupled to the amplifying light waveguide piece and includes a semiconductor laser for generating pump light for the amplifying light waveguide piece. A control device regulates the wavelength of the pump light generated by the semiconductor laser to be within a desired wavelength range so that the pump light is maximally absorbed in the amplifying light waveguide piece.
    Type: Grant
    Filed: February 19, 1993
    Date of Patent: November 8, 1994
    Assignee: Alcatel N.V.
    Inventor: Rolf Heidemann
  • Patent number: 5337175
    Abstract: Optical communications system for the subscriber area with optical amplifiers.The system according to the invention is used to distribute information signals, particularly telephone signals, from a center to a plurality of subscribers and to make possible a bidirectional transmission of telephone and data signals between the center and the subscribers. According to the invention, the network used for this purpose is a multistar fiber-optic network in which fiber-optic amplifiers (10, 11) are present between successive branch points. The information signals to be distributed are transmitted via the fiber-optic network with a first wavelength (.lambda..sub.1) to the subscribers, and the subscriber-specific information signals to be transmitted from the center (1) to the subscribers (T.sub.i) are converted by frequency modulation to a different frequency band (FB.sub.
    Type: Grant
    Filed: February 11, 1992
    Date of Patent: August 9, 1994
    Assignee: Alcatel N.V.
    Inventors: Horst Ohnsorge, Adolf Weygang, Rolf Heidemann
  • Patent number: 5335109
    Abstract: An optical amplifier is provided through which an incoming optical signal passes before entering an optical-to-electric transducer. The level of the optical signal output by the optical amplifier is controlled by a controller based on the electrical signal output by the transducer.
    Type: Grant
    Filed: February 19, 1993
    Date of Patent: August 2, 1994
    Assignee: Alcatel N.V.
    Inventor: Rolf Heidemann
  • Patent number: 5333089
    Abstract: An optical communications system includes an optical transmitter equipped with a semiconductor laser for generating a light signal and a light waveguide path for transmitting the generated light signal to an optical receiver in whose light waveguide path at least one fiber-optic amplifier is included. The fiber-optic amplifier is equipped with an amplifying light waveguide piece. The optical transmitter includes a control device having a reference waveguide piece, which regulates an emission wavelength of the semiconductor laser in dependence on absorption of the light signal in the reference light waveguide piece. The reference waveguide piece has a maximum in absorption at a wavelength at which the amplifying light waveguide piece of the at least one fiber-optic amplifier has a maximum in emission.
    Type: Grant
    Filed: February 19, 1993
    Date of Patent: July 26, 1994
    Assignee: ALCATEL N.V.
    Inventor: Rolf Heidemann
  • Patent number: 5302922
    Abstract: To compensate for nonlinear distortions in analog optical communication transmission systems, caused by laser chirps and the chromatic dispersion of the optical fiber, an equalizer in the form of an LC component is known, whose capacitance is formed by a variable capacitance diode. If this equalizer is to be adjusted for considerable signal distortions (long transmission path length), it must operate at great capacitance, which reduces its bandwidth. In order to be able to equalize large bandwidth signals (e.g. 600 MHz) containing considerable distortions, the invention indicates an LC chain circuit with LC components of the known type, as the equalizer. Further developments of this solution concern the appropriate polarizing of the variable capacitance diode and maintaining the frequency response constant, when adjusting the equalization.
    Type: Grant
    Filed: June 29, 1992
    Date of Patent: April 12, 1994
    Assignee: Alcatel N.V.
    Inventors: Rolf Heidemann, Heinz Krimmel, Bernhard Junginger
  • Patent number: 5297154
    Abstract: Prior art fiber-optic amplifiers which are used in a fiber-optic link to amplify the light signals to be transmitted have the disadvantage that the semiconductor lasers employed as pump lasers are highly sensitive to feedback, so that the stability of the light-signal transmission is impaired by pump light reflected back into the pump lasers.According to the invention, the operating current for such pump lasers (4) contains a noise current, so that the pump laser emits its pump light in many modes, which makes it insensitive to feedback.To prevent the noise component of the pump light which is caused by the noise current from affecting the amplification of the light signals to be transmitted, the noise current is filtered in such a way that its spectral components have frequencies which lie above the reciprocal lifetime of that energy level of the active laser medium which causes the amplification of the light signals.
    Type: Grant
    Filed: April 30, 1993
    Date of Patent: March 22, 1994
    Assignee: Alcatel SEL A.G.
    Inventors: Rolf Heidemann, Jurgen Otterbach
  • Patent number: 5291326
    Abstract: A system for optically transmitting a useful signal (S.sub.1) from a transmitter (1) over a transmission link which includes either an optical waveguide (3) or a fiber-optic network coupled to a receiver (2). The transmitter (1) transmits the useful signal (S.sub.1) and an auxiliary signal (S.sub.2) over the transmission link toward the receiver (2) at different wavelengths. Circuits (4a, 4b, 5, 6, 7) at a desired point in the transmission link and analyze the auxiliary signal (S.sub.2) and provide a response signal (S.sub.3) containing information for monitoring the useful signal. The transmitter (1) receives the response signal (S.sub.3) and controls the further transmission of the useful signal (S.sub.1) and the auxiliary signal (S.sub.2) in accordance with the information in the response signal (S.sub.3).
    Type: Grant
    Filed: March 20, 1992
    Date of Patent: March 1, 1994
    Assignee: Alcatel N.V.
    Inventor: Rolf Heidemann