摘要:
An optical channel monitor is described, the optical channel monitor includes an optical input port, a photodetector disposed in an optical path communicating at least intermittently with the optical input port, an optical filter disposed in the optical path between the optical input port and the photodetector, and an optical band splitter disposed in the optical path between the optical filter and the photodetector. The optical filter is a multibandpass filter, such as a scanning Fabry-Perot filter. The optical channel monitor also comprises a reference light system for providing a calibration standard against which an optical signal input through the input port may be compared. The channel monitor finds application in optical transmission systems including wavelength division multiplexed (WDM) optical communication systems.
摘要:
A new optical sensing device containing fiber Bragg gratings, a scanning bandpass filter, an interferometer and multiple photodetectors is disclosed. The present invention also describes a new system and method for fibre Bragg grating (FBG) sensor interrogation and multiplexing. The new system combines a scanning Fabry-Perot (SFP) bandpass filter used to wavelength-multiplex multiple gratings in a single fiber, and an unbalanced Mach-Zehnder fibre interferometer made with a 3×3 coupler to detect strain-induced wavelength shifts. A passive technique for interferometer drift compensation using non-sensing FBGs is included in the system. A complete prototype system interrogates four gratings in a single fiber at a Nyquist sampling rate up to 10 kHz, with a noise floor measured near 4 n&egr; Hz−1/2 above 0.1 Hz. The inclusion of the interferometer drift compensation technique is shown to make quasi-static measurements feasible.
摘要:
A passive, temperature compensated tunable filter calibration device for a Bragg grating interrogation system. In a first system, a dual-substrate Bragg grating calibration system, the temperature of an array of gratings is estimated using an array of gratings bonded to a common host substrate and a single grating bonded to a material with a different coefficient of thermal expansion. Changes in a common temperature of the substrates is measured by monitoring the difference between shifts of grating wavelength. As a filter voltage is scanned from its lowest to its highest voltage, the voltages are recorded. The second lowest wavelength corresponds to the grating attached to the differing substrate. The voltages are used to calculate a voltage-to-wavelength function for the scanning range of the filter. To compensate for variations in a calibration curve and temperature variations of the calibration array, the temperature is estimated and function re-calculated at every pass of the scanning filter. In a second system, a hydrogen-cyanide wavelength reference absorption cell that absorbs light at discrete wavelengths corresponding to the molecular vibrational mode frequencies of the gas. With a broadband optical light input to the cell, the output displays the spectrum of the input with several narrow dips in the spectra corresponding to the absorption lines of the cell. A first photodetector sees the transmission spectrum and a second sees the reflections from Bragg gratings in a sensing array. The filter drive voltages that coincide with the dips of the transmission spectrum are used to calibrate the voltage-to-wavelength function of the scanning filter. In this system there is no temperature compensation step as the absorption lines are not sensitive to temperature.
摘要:
A passive, temperature compensated tunable filter calibration device in a Bragg-grating interrogation system. The invention comprises two systems: 1) a dual substrate Bragg grating calibration system, the temperature of an array of gratings is estimated using an array of gratings bonded to a common host substrate and a single grating bonded to a material with a different coefficient of thermal expansion; 2) a hydrogen cyanide wavelength reference absorption cell that absorbs light at discrete wavelengths corresponding to the molecular vibration mode frequencies of the gas. A first photodetector sees the transmission spectrum and a second sees the reflections from Bragg gratings in a sensing array. In this system there is no temperature compensation step as the absorption lines are not sensitive to temperature.
摘要:
The invention includes a method and apparatus for monitoring wavelength of an optical channel. A tunable optical bandpass filter is used to correlate a signal from an optical transmission line with a signal from a reference light source. The signal from the reference light source passes through a reference gas cell. The absorption lines of the reference gas provide a known calibration standard against which measured values may be compared. The invention finds applications in optical transmission systems, including wavelength division multiplexed and dense wavelength division multiplexed (WDM and DWDM) optical communication systems.
摘要:
According to a preferred embodiment of the present invention, there is provided a mobile telephone handset construction, which is adapted to be attached removably in an inverted manner to a support element, such as a strap, loop or ring attached to a back-pack or other article of wearing apparel, or any other suitable support element used for supporting the handset construction. The construction of an embodiment of the invention can be quickly retrieved and responded to in a convenient manner when a call is being received. The construction includes a display mounted at a top front face portion of a housing to present information to the user when the display is viewed in a position adapted to be read by the user. A carabiner latch is connected to the housing for attaching to the support element to suspend the construction therefrom in an inverted manner for storage purposes. The latch is secured to a bottom portion of the housing at a substantial distance from the display to enable the handset construction to be suspended in an inverted substantially vertical position from the support element and able to be moved pivotally from the inverted position by the hand of the user in a quick and convenient manner to a position where the user is permitted to read the information contained on the display. All of this can be accomplished while the construction remains attached to the support element.
摘要:
A mobile telephone handset includes an elongated housing having a carabiner latch pivotally attached at a battery door on the rear side of the housing. The carabiner latch includes a hook portion having a spring-biased latch pivotally attached thereto for attaching the latch to a support element, such as a strap, loop or ring attached to a back-pack or other article of wearing apparel. The latch is stored within a door recess that receives the latch for storage purposes. The latch can be swung outwardly away from the housing to a variety of positions. A cylindrical projection is disposed within the door recess for frictionally receiving a central opening of the latch. A finger grip recess disposed within the door facilitates the grasping of the latch when it is disposed within the recess to facilitate swinging it away from the housing and out of the recess.
摘要:
A multi-panel device is disclosed. In a particular embodiment, the device includes a first hinge coupled to a first panel and coupled to a second panel. The first panel includes a first display surface and the second panel includes a second display surface. The second hinge is coupled to the second panel and coupled to a third panel that includes a third display surface. The device also includes a sensor coupled to the first hinge to detect a relative orientation of the first panel to the second panel. The device includes a processor responsive to the sensor to detect a device configuration. The processor is configured to adjust a user interface displayed at the first display surface, the second display surface, and the third display surface based on the detected device configuration.
摘要:
A multi-panel device with a configurable interface is disclosed. In a particular embodiment, the device includes a hinge rotatably coupled to a first panel of the device via a first pin and rotatably coupled to a second panel of the device via a second pin. The first pin is engaged within a slot of the first panel to enable a lateral movement of the first panel relative to the second panel such that the first panel has a first range of motion relative to the second panel when the hinge is in an extended configuration and a second range of motion when the hinge is in a retracted configuration. The first range of motion is larger than the second range of motion.
摘要:
A system for synchronizing chaotic transmitters and receivers that is less sensitive to channel effects than other known chaotic communication methods. The system employs duplicate transmitter and receiving modules and in addition to the chaotic output a synchronizing signal which occupies a reduced bandwidth. The small bandwidth affords the system a greater resistance to the affects of frequency dependent channel distortion and noise. The broad band chaotic signal is transmitted and appears to be noise to an unauthorized listener. The receiving unit employs band pass filtering, and when the signal is received the receiver filters the chaotic signal through band pass filters which eliminate channel noise and make gain control easier to implement.