Abstract: This application discloses a voice activity detection method. The method includes receiving speech data, the speech data including a multi-frame speech signal; determining energy and spectral entropy of a frame of speech signal; calculating a square root of the energy of the speech signal and/or calculating a square root of the spectral entropy of the frame of the speech signal; determining a spectral entropy-energy square root of the frame of the speech signal based on at least one of the square root of the energy and the square root of the spectral entropy; and determining that the frame of the speech signal is an unvoiced frame if the spectral entropy-energy square root of the speech signal is less than a first threshold, or that it is a voiced frame if the spectral entropy-energy square root of the speech signal is greater than or equal to the first threshold.

Abstract: This application discloses a voice activity detection method. The method includes receiving speech data, the speech data including a multi-frame speech signal; determining energy and spectral entropy of a frame of speech signal; calculating a square root of the energy of the speech signal and/or calculating a square root of the spectral entropy of the frame of the speech signal; determining a spectral entropy-energy square root of the frame of the speech signal based on at least one of the square root of the energy and the square root of the spectral entropy; and determining that the frame of the speech signal is an unvoiced frame if the spectral entropy-energy square root of the speech signal is less than a first threshold, or that it is a voiced frame if the spectral entropy-energy square root of the speech signal is greater than or equal to the first threshold.

Abstract: An apparatus comprising a laser transmitter having a first side and a second side, a filter coupled to the first side, a detector coupled to the second side, and a temperature controller coupled to the laser transmitter and the detector. Also disclosed is an apparatus comprising at least one processor configured to implement a method comprising receiving a photocurrent of a backward light from a laser, determining a wavelength shift offset between a wavelength of the output light and a filter transmission peak, and adjusting a temperature of the laser to substantially reduce the wavelength shift and align the wavelength of the output light with the filter transmission peak.

Abstract: An optical network transmitter comprising a fractional-bit delay module, an optical modulator coupled to the fractional-bit delay module, and a band-limiting optical filter coupled to the optical modulator. Also disclosed is a transmission system comprising a source configured to generate two complementary binary data streams, a fractional-bit delay module in communication with the source and configured to delay one of the complementary binary data streams, a modulation module in communication with the source and the fractional-bit delay module and configured to convert the undelayed complementary binary data streams and the delayed complementary binary data streams into a fractional-bit delayed optical duobinary signal, and a band-limiting node in communication with the modulation module and configured to filter and transmit the optical duobinary signal.

Abstract: An apparatus comprising a laser transmitter having a first side and a second side, a filter coupled to the first side, a detector coupled to the second side, and a temperature controller coupled to the laser transmitter and the detector. Also disclosed is an apparatus comprising at least one processor configured to implement a method comprising receiving a photocurrent of a backward light from a laser, determining a wavelength shift offset between a wavelength of the output light and a filter transmission peak, and adjusting a temperature of the laser to substantially reduce the wavelength shift and align the wavelength of the output light with the filter transmission peak.

Abstract: An optical network transmitter comprising a fractional-bit delay module, an optical modulator coupled to the fractional-bit delay module, and a band-limiting optical filter coupled to the optical modulator. Also disclosed is a transmission system comprising a source configured to generate two complementary binary data streams, a fractional-bit delay module in communication with the source and configured to delay one of the complementary binary data streams, a modulation module in communication with the source and the fractional-bit delay module and configured to convert the undelayed complementary binary data streams and the delayed complementary binary data streams into a fractional-bit delayed optical duobinary signal, and a band-limiting node in communication with the modulation module and configured to filter and transmit the optical duobinary signal.