Patents by Inventor Hiromu Toba

Hiromu Toba 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).

  • Publication number: 20080226298
    Abstract: The present invention has been achieved to provide a novel optical transmission system realizing high-speed optical transmission over greater distance by suppressing waveform degradation caused by mode dispersion and mode transition in a multimode optical transmission line. The optical transmission system of the present invention includes: an optical transmitter for transmitting incoherent light; an excitation mechanism for exciting a predetermined mode in the incoherent light transmitted from the optical transmitter; a multimode optical transmission line for transmitting the incoherent light transmitted from the excitation mechanism; a transmission mechanism for transmitting a predetermined mode in the incoherent light transmitted from the excitation mechanism; and an optical receiver for receiving the incoherent light transmitted from the transmission mechanism or the incoherent light transmitted from the transmission mechanism.
    Type: Application
    Filed: September 16, 2004
    Publication date: September 18, 2008
    Applicants: Nippon Telegraph and Telephone Corporation, NTT Electronics Corporation
    Inventors: Hiroyuki Fukuyama, Toshihiro Itoh, Satoshi Tunashima, Kimikazu Sano, Koichi Murata, Yohtaro Umeda, Yasuo Tazoh, Hirohiko Sugahara, Hiromu Toba, Masahiro Muraguchi, Senichi Suzuki, Seiji Fukushima, Yoshinori Hibino, Tadashi Sakamoto, Yoshiaki Yamabayashi, Eiji Yoshida, Ryuichi Iwamoto
  • Patent number: 7002968
    Abstract: A signal transport system and a transport method are provided. A whole lowspeed signal containing a client overhead received from a client network is transparently subjected to time division multiplexing and an additional overhead is inserted in the whole signal and further subjected to wavelength division multiplexing, so that the digital signal having the addition overhead is transported in the wavelength division mode represented by one wavelength to a receiving equipment.
    Type: Grant
    Filed: September 18, 2000
    Date of Patent: February 21, 2006
    Assignee: Nippon Telegraph and Telephone Corporation
    Inventors: Masahito Tomizawa, Yoshiaki Kisaka, Yutaka Miyamoto, Takashi Ono, Hiromu Toba
  • Patent number: 6865348
    Abstract: A system which improves wavelength tolerance, compensates dispersion in a simple way, reduces limitation of the fiber input power is disclosed. The operation includes receiving a clock signal from a system clock source; modulating a single mode optical signal based on the clock signal and generating an optical pulse signal having two longitudinal modes, the frequency interval thereof being n×B, n being a natural number and B being a transmission speed; generating a partial response signal by converting a binary NRZ signal from a digital signal source in synchronism with the system clock source; and modulating the optical pulse signal based on the partial response signal, and outputting a binary RZ modulated signal. The binary RZ modulated signal is input into a receiver, where two partial response components in the optical spectra of the input signal are divided, and one or both of the components are received.
    Type: Grant
    Filed: February 28, 2001
    Date of Patent: March 8, 2005
    Assignee: Nippon Telegraph and Telephone Corporation
    Inventors: Yutaka Miyamoto, Akira Hirano, Kazushige Yonenaga, Kenji Sato, Hiromu Toba, Akihiko Matsuura
  • Publication number: 20010017724
    Abstract: A system which improves wavelength tolerance, compensates dispersion in a simple way, reduces limitation of the fiber input power is disclosed. The operation includes receiving a clock signal from a system clock source; modulating a single mode optical signal based on the clock signal and generating an optical pulse signal having two longitudinal modes, the frequency interval thereof being n×B, n being a natural number and B being a transmission speed; generating a partial response signal by converting a binary NRZ signal from a digital signal source in synchronism with the system clock source; and modulating the optical pulse signal based on the partial response signal, and outputting a binary RZ modulated signal. The binary RZ modulated signal is input into a receiver, where two partial response components in the optical spectra of the input signal are divided, and one or both of the components are received.
    Type: Application
    Filed: February 28, 2001
    Publication date: August 30, 2001
    Inventors: Yutaka Miyamoto, Akira Hirano, Kazushige Yonenaga, Kenji Sato, Hiromu Toba, Akihiko Matsuura