Abstract: The present invention has an object to provide a technology for monitoring the quality of a WDM signal light, capable of quickly and accurately judging an occurrence of quality deterioration of signal light and a deterioration factor thereof. To this end, according to a quality monitoring apparatus of WDM signal light of the present invention, a part of the WDM signal light being propagated through an optical transmission path is branched as a monitor light, a signal light of one wavelength contained in the monitor light is selected as a channel to be measured.

Abstract: A plurality of pump light sources generate plural variations of pump light having different frequencies. A modulation circuit intensity-modulates the plural variations of pump light in the predetermined periods, respectively. A pump light pair whose frequency difference equals a Raman shift frequency are modulated such that they cannot simultaneously enters an emission state. A wavelength-multiplexer wavelength-multiplexes the plural variations of pump light modulated by the modulation circuit. A optical guide device guides the plural variations of pump light wavelength-multiplexed by the wavelength-multiplexer to an optical fiber.

Abstract: It is an object of the present invention to provide a Raman amplifier capable of easily reducing the wavelength deviation of a Raman gain while suppressing system performance degradation, and an optical transmission system using such a Raman amplifier.

Abstract: A wavelength converter which employs an optical fiber and has high converter efficiency. The polarization planes of a signal light and an exciting light outputted from a laser diode (LD) (103) are respectively controlled by polarization controllers (PC's) (101 and 104) and the phases of the lights are respectively modulated by phase modulators (PM's) (102 and 105) in accordance with modulation signals outputted form an oscillator (110). Then, the output lights form the PM's (102 and 105) are multiplexed by a coupler (106). After the multiplexed signal light and exciting light are amplified by an optical amplifier (EDFA) (107), they are imputed to a dispersion shift fiber (DSP) (108). After wavelength transformation (four light waves mixing (FWM) is practiced in the DSP, and FWM light is outputted through a band-pass filter (BPF) (109).

Abstract: A plurality of pump light sources generate plural variations of pump light having different frequencies. A modulation circuit intensity-modulates the plural variations of pump light in the predetermined periods, respectively. A pump light pair whose frequency difference equals a Raman shift frequency are modulated such that they cannot simultaneously enters an emission state. A wavelength-multiplexer wavelength-multiplexes the plural variations of pump light modulated by the modulation circuit. A optical guide device guides the plural variations of pump light wavelength-multiplexed by the wavelength-multiplexer to an optical fiber.

Abstract: It is an object of the present invention to provide a Raman amplifier capable of easily reducing the wavelength deviation of a Raman gain while suppressing system performance degradation, and an optical transmission system using such a Raman amplifier.

Abstract: The present invention has an object to provide a technology for monitoring the quality of a WDM signal light, capable of quickly and accurately judging an occurrence of quality deterioration of signal light and a deterioration factor thereof. To this end, according to a quality monitoring apparatus of WDM signal light of the present invention, a part of the WDM signal light being propagated through an optical transmission path is branched as a monitor light, a signal light of one wavelength contained in the monitor light is selected as a channel to be measured.

Abstract: A span between an optical transmitting end station and an optical repeater node, a span between optical repeater nodes, a span between an optical repeater node and a receiving end station, and a span between an optical repeater node and a CN/OADM/HUB node are set as first dispersion compensation sections. Additionally, a span between the optical transmitting end station and a CN/OADM/HUB node, a span between CN/OADM/HUB nodes, and a span between a CN/OADM/HUB node and the receiving end station are set as second dispersion compensation sections. In the first dispersion compensation sections, dispersion compensation is made so that residual dispersion becomes a predetermined negative value. In the second dispersion compensation sections, dispersion compensation is made so that residual dispersion becomes a positive value.

Abstract: The present invention aims at providing a Raman amplifier and an optical transmission system, capable of reducing characteristic deterioration to be caused by excitation lights mixedly existing within a wavelength band of signal lights. To this end, the Raman amplifier of the present invention comprises an excitation light source that generates excitation lights having a wavelength band overlapped with a wavelength band of the signal lights, a multiplexing unit that supplies the excitation lights to an optical transmission path, and an optical filter that suppresses optical components which are included in lights propagated through an optical transmission path and are of the same wavelengths as those of the excitation lights.

Abstract: The present invention aims at providing a Raman amplifier and an optical transmission system, capable of reducing characteristic deterioration to be caused by excitation lights mixedly existing within a wavelength band of signal lights. To this end, the Raman amplifier of the present invention comprises an excitation light source that generates excitation lights having a wavelength band overlapped with a wavelength band of the signal lights, a multiplexing unit that supplies the excitation lights to an optical transmission path, and an optical filter that suppresses optical components which are included in lights propagated through an optical transmission path and are of the same wavelengths as those of the excitation lights.

Abstract: A heating apparatus includes a heater 6 which includes a first heating conductor pattern 1, a second heating conductor patterns 2 and an elongated plate-shaped member 3 made of heat-resistive and insulated material. The first heating conductor pattern 1 is disposed in the central portion in a longitudinal direction of the plate-shaped member 3. The second heating conductor patterns are disposed in both end portions of the plate-shaped member in the longitudinal direction. The first heating conductor pattern 1 and the second heating conductor patterns 2 are independently controlled their temperature. Current is first fed to the first heating conductor pattern 1, and the current feeding is stopped, and current is then fed to the second heating conductor patterns 2. Accordingly, the protective member placed on and along the heater 6 is gradually heated from the center to both ends.

Abstract: A heating apparatus includes a heater 6 which includes a first heating conductor pattern 1, a second heating conductor patterns 2 and an elongated plate-shaped member 3 made of heat-resistive and insulated material. The first heating conductor pattern 1 is disposed in the central portion in a longitudinal direction of the plate-shaped member 3. The second heating conductor patterns are disposed in both end portions of the plate-shaped member in the longitudinal direction. The first heating conductor pattern 1 and the second heating conductor patterns 2 are independently controlled their temperature. Current is first fed to the first heating conductor pattern 1, and the current feeding is stopped, and current is then fed to the second heating conductor patterns 2. Accordingly, the protective member placed on and along the heater 6 is gradually heated from the center to both ends.

Abstract: A heating apparatus includes a heater 6 which includes a first heating conductor pattern 1, a second heating conductor patterns 2 and an elongated plate-shaped member 3 made of heat-resistive and insulated material. The first heating conductor pattern 1 is disposed in the central portion in a longitudinal direction of the plate-shaped member 3. The second heating conductor patterns are disposed in both end portions of the plate-shaped member in the longitudinal direction. The first heating conductor pattern 1 and the second heating conductor patterns 2 are independently controlled their temperature. Current is first fed to the first heating conductor pattern 1, and the current feeding is stopped, and current is then fed to the second heating conductor patterns 2. Accordingly, the protective member placed on and along the heater 6 is gradually heated from the center to both ends.

Abstract: In radiocommunication apparatus, two downconverters (41, 42) for use in reception system each heterodyne their respective received RF signal to an intermediate frequency. One of the downconverters employs a local signal generated by a synthesizer (19), and the other employs a signal obtained by dividing the frequency of the local signal by a factor of N. Two upconverters (161, 162) for use in transmission system each convert their respective input transmit signal to a transmit RF signal. One of the upconverters employs a local signal generated by the synthesizer (19) and the other employs a signal obtained by dividing the frequency of the local signal by a factor of N.

Abstract: A radio communication apparatus comprises an analog I/Q signal generator, a digital demodulator, and an interference wave suppression control block. The interference wave suppression block detects a gain difference between an in-phase component and a double quadrature component, based on an input and output signals of a low pass filter in the digital demodulator and the output of the double quadrature mixer, and controls a reference voltage of an A/D converter in the digital demodulator. Therefore, it is possible to reduce the gain difference of the in-phase component and the quadrature component, and to effectively eliminate an interference wave mixed in a base band signal. Furthermore, a radio communication apparatus according to the present invention comprises an antenna input block, a reception block, a transmission block, and an in/out block. Because a frequency when sending data is equal to the frequency when receiving data, it is possible to quickly change transmission and reception.

Abstract: A first local signal required for a downconverter of a reception system and an upconverter of a transmission system in a first band is generated by a synthesizer for generating a variable high frequency local signal. A second local signal required for a downconverter of a reception system and an upconverter of a transmission system in a second band is generated by mixing a signal generated by an oscillator for generating a signal at a relatively low fixed frequency with the first local signal using a mixer and filtering the result using a high-pass filter.

Abstract: There is provided a radio communication apparatus wherein a band-pass filter and a variable attenuator of a radio high-frequency circuit are designed such that these can be commonly used by transmitter and receiver systems. In a base-band circuit system, analog low-pass filters for smoothing a base-band signal and roll-off filters for removing unnecessary frequency components by digital filtering processing are designed such that these can be commonly used by the transmitter system and receiver system. In the demodulation system adopted in the orthogonal circuit system, orthogonal detection is followed by delay detection, and multipliers for orthogonal modulation are also used as multipliers for orthogonal demodulation. Further, for common use of the circuit elements by the transmitter system and receiver system, switches for connecting the signal line to the transmitter system or the receiver system in the transmission/reception mode are provided at one end or both ends of each of these circuits.

Abstract: In one embodiment, a resonant circuit comprising a ground-contacting conductive member, a dielectric layer provided on the ground-contacting conductive layer, a ground-contacting member provided on the dielectric layer and electrically connected to the ground-contacting conductive member, and a U-shaped microstrip line formed on the dielectric layer. Both ends of the U-shaped microstrip line face the ground-contacting member. One of them is connected to the ground-contacting member through a lumped capacitor, and the other end is directly connected to the ground-contacting member.

Abstract: An electronically controllable tuning device includes a voltage controlled oscillator adapted to have an oscillation frequency controlled by a control voltage and simultaneously generate a fundamental wave of a predetermined frequency, a programmable frequency divider for dividing the fundamental wave frequency at a frequency division ratio corresponding to the control of a channel selection means and a phase locked loop adapted to compare the fundamental wave phase with the phase of the output of the programmable divider to generate a comparison output and feeding the comparison output back to the voltage controlled oscillator to control the output frequency of the voltage controlled oscillator. The tuning device further includes means for supplying as a local oscillation signal to an intermediate frequency generating mixer one of higher harmonic wave components of the fundamental wave.

Abstract: A channel-selecting apparatus in which is designed to determine the oscillation frequencies of a local oscillator and/or the tuning frequencies of a radio-frequency amplifier for all channels by varying analogue dc voltages being applied to a frequency control element such as a variable capacitance diode included in the oscillator and/or the amplifier in accordance with channel selective operation. Digital memory devices are provided each of which previously stores digital information representing the different predetermined analogue voltages assigned to all the channels being applied to the frequency control element. Digital information stored in the memory devices is read out upon selective operation of any of channel selection switches each coupled with the corresponding one of bistable multivibrators.