Abstract: Disclosed is a frequency hopping modulation method in a communication system. The method includes: generating a frequency hopping pattern according to a hopping frequency's level; generating a hopping frequency through use of the frequency hopping pattern; modulating an original signal to a frequency hopping spread signal by multiplying the original signal by the hopping frequency; generating a chirp pulse code for diversifying the frequency hopping spread signal; and modulating the frequency hopping spread signal to a chirp pulse signal by multiplying the frequency hopping spread signal by the chirp pulse code.

Abstract: Provided is a location measurement method of a mobile node using a predictive filter is provided for improving the location measurement accuracy of the mobile node. The location measurement method of a mobile node detects change of movement pattern of the mobile node, corrects weights of a location measurement period and a predictive filter depending on the change of movement pattern, and compensates a location of the mobile node using the corrected weights of the location measurement period and predictive filter.

Abstract: A method and apparatus for measuring a distance in a wireless environment are provided, in which a first device transmits a distance measurement signal to a second device and receives at least one response signal for the distance measurement signal from the second device, matches the received response signal with a reference signal to detect an earliest response signal, and calculates a time taken from the transmission of the distance measurement signal to the second device and the reception of the response signal from the second device using a peak value of the matched reference signal.

Abstract: An indoor location system having a sensor and a method for checking an indoor location using the indoor location system are disclosed. The method includes: calculating a current location coordinate by using nodes; calculating a first movement distance by comparing the current location coordinate and a stored previous location coordinate; calculating a second movement distance through a sensor; and storing the current location coordinate instead of the previous location coordinate when the distance between the first movement distance and the second movement distance is smaller than a predetermined threshold value. Accordingly, an accurate location of an object can be recognized indoors and an error can be prevented from being caused when the location of the object is recognized.

Abstract: Disclosed is a broadband light source (BLS) necessary to implement wavelength-locked Fabry-Perot (FP) laser diodes (LDs) applicable to an optical subscriber network The BLS is based on a method using mutual injection of low-cost FP LDs and a method using FP LDs undergoing chirping. A power level of a light emitting diodes (LED), an erbium-doped fiber amplifier (EDFA), or a super luminescent diode (SLD) used as the conventional BLS is low and its cost is high, such that the conventional BLS is inefficient. However, the present invention can easily implement a low-cost BLS using proposed FP LDs.

Abstract: The present invention relates to a passive optical network, which inexpensively improves the spectral efficiency of an access network and is capable of increasing the number of subscribers per channel by using WDM in combination with Time Division Multiplexing (TDM) or SubCarrier Multiple Access (SCMA) to expand a conventional WDM passive optical network.

Abstract: Disclosed is a frequency hopping modulation method in a communication system. The method includes: generating a frequency hopping pattern according to a hopping frequency's level; generating a hopping frequency through use of the frequency hopping pattern; modulating an original signal to a frequency hopping spread signal by multiplying the original signal by the hopping frequency; generating a chirp pulse code for diversifying the frequency hopping spread signal; and modulating the frequency hopping spread signal to a chirp pulse signal by multiplying the frequency hopping spread signal by the chirp pulse code.

Abstract: Provided is a location measurement method of a mobile node using a predictive filter is provided for improving the location measurement accuracy of the mobile node. The location measurement method of a mobile node detects change of movement pattern of the mobile node, corrects weights of a location measurement period and a predictive filter depending on the change of movement pattern, and compensates a location of the mobile node using the corrected weights of the location measurement period and predictive filter.

Abstract: A method and apparatus for measuring a distance in a wireless environment are provided, in which a first device transmits a distance measurement signal to a second device and receives at least one response signal for the distance measurement signal from the second device, matches the received response signal with a reference signal to detect an earliest response signal, and calculates a time taken from the transmission of the distance measurement signal to the second device and the reception of the response signal from the second device using a peak value of the matched reference signal.

Abstract: An indoor location system having a sensor and a method for checking an indoor location using the indoor location system are disclosed. The method includes: calculating a current location coordinate by using nodes; calculating a first movement distance by comparing the current location coordinate and a stored previous location coordinate; calculating a second movement distance through a sensor; and storing the current location coordinate instead of the previous location coordinate when the distance between the first movement distance and the second movement distance is smaller than a predetermined threshold value. Accordingly, an accurate location of an object can be recognized indoors and an error can be prevented from being caused when the location of the object is recognized.

Abstract: Disclosed is a broadband light source (BLS) necessary to implement wavelength-locked Fabry-Perot (FP) laser diodes (LDs) applicable to an optical subscriber network The BLS is based on a method using mutual injection of low-cost FP LDs and a method using FP LDs undergoing chirping. A power level of a light emitting diodes (LED), an erbium-doped fiber amplifier (EDFA), or a super luminescent diode (SLD) used as the conventional BLS is low and its cost is high, such that the conventional BLS is inefficient. However, the present invention can easily implement a low-cost BLS using proposed FP LDs.

Abstract: An optical network terminator of the present invention includes an optical wavelength division multiplexer for receiving an optical signal and incoherent light. An optical detection unit converts a downstream high speed and low speed optical signals into electrical signals. A laser diode converts an upstream signal into an optical signal. A high speed driving unit is supplied with power from a power supply unit to drive a forward-biased laser diode and establish a data and video channel. A high speed reception unit is supplied with the power to receive a downstream data and video channel. A charging unit outputs charged power at the time of a power failure. A low speed driving unit is supplied with the charged power to reverse-bias the laser diode to establish a voice channel. A low speed reception unit is supplied with the charged power to receive a voice channel.

Abstract: An optical amplifier comprises a wavelength tunable filter, one or more optical gain stages, and a controller for controlling a spectral profile of the wavelength tunable filter in response to a measured spectral characteristic of the amplifier. The controller may also control gain of the gain stage(s). The controller determines the filter spectral profile necessary to obtain a desired amplifier spectral characteristic. The spectral characteristic may, for example, be a power spectral output of the amplifier or a gain profile of the amplifier. The amplifier may incorporate a dispersion compensator. The controller may control a spectral profile of the wavelength tunable filter and gain of the dispersion compensator. A tunable fiber light source is also described.

Abstract: An optical amplifier comprises a wavelength tunable filter, one or more optical gain stages, and a controller for controlling a spectral profile of the wavelength tunable filter in response to a measured spectral characteristic of the amplifier. The controller may also control gain of the gain stage(s). The controller determines the filter spectral profile necessary to obtain a desired amplifier spectral characteristic. The spectral characteristic may, for example, be a power spectral output of the amplifier or a gain profile of the amplifier. The amplifier may incorporate a dispersion compensator. The controller may control a spectral profile of the wavelength tunable filter and gain of the dispersion compensator. A tunable fiber light source is also described.