1902 results about "Chirp" patented technology

A dynamic equalization system 12 for use in audio reproduction systems. The apparatus includes a chirp tone generator 38 which produces a tone having multiple frequencies. The chirp tone is broadcast into the listening space 10 from a transducer 14. The broadcast chirp tone is monitored by a second transducer 22 at the listening position to produce a received chirp tone. The received tone and the original tone are compared in a coefficient computer 44 connected to a programmable equalizer 42. The equalizer 42 uses the signal from the coefficient computer to compensate for irregularities 47 in listening space 10 and transducer 14 to produce a substantially undistorted listening experience from source 28 in listening space 10. The first step of the method of the invention is generation of a chirp tone. The chirp tone includes multiple frequencies. The chirp tone is broadcast into the listening space from a transducer placed at the selected transducer position. The broadcast chirp tone is next monitored by a transducer at the listening position to produce a received chirp tone. The received tone is then compared to the generated chirp tone and differences noted. The differences are used to program an equalizer for correction of sound. The process is done for each position where a transducer is located. Finally, sound from a program source is routed through the equalizer to the transducers for a corrected sound.

A fiber optic transmitter comprising a digital driver adapted to adjust the crossing point of a digital base signal, an optical source adapted to receive the digital base signal and produce a frequency modulated optical signal, and an optical spectrum reshaper adapted to convert the frequency modulated optical signal to an amplitude modulated optical signal. A method for transmitting a signal, comprising: adjusting the crossing point of a digital base signal; providing the adjusted signal to an optical source to produce a frequency modulated optical signal; and providing the frequency modulated optical signal to an optical spectrum reshaper to convert the frequency modulated optical signal to an amplitude modulated optical signal.

An optical transmission system has a directly modulated laser for modulating data directly on an optical signal, and a narrow band optical filter having a band center frequency offset from a central optical frequency of the optical signal, to reduce the phase difference between FM and AM of the modulated optical signal, the filter having a bandwidth sufficiently narrow to substantially remove frequencies outside a spectrum of adiabatic frequency chirp resulting from the modulation, combined with Fourier broadening caused by the data modulation. This is a cost effective way of improving the dispersion tolerance to give greatly improved system reach and to make it practical to use directly modulated lasers with existing NDSF. The narrow band filter can be located at the transmitter or the receiver, and can have a center frequency locked to a feature in the frequency spectrum of the laser.

The transmission system includes a first electro-optical modulator adapted to supply in response to an input electrical signal a controlled phase optical signal having an optical power modulated between low levels and high levels and a phase shift within each time cell that contains a low power level. To make it more flexible to use, the system includes a second electro-optical modulator controlled by the input signal and optically coupled to the first electro-optical modulator to apply to said controlled phase optical signal complementary power and/or phase modulation so as respectively to modify its extinction ratio and/or to apply a transient "chirp" to it.

To reduce a delay between a time that a user of an originating mobile station (MS) requests to set up a Push-To-Talk (PTT) call and the time that the user may begin to speak, a communication system provides a ‘wake up list’ of other mobile stations (MSs) that may be awakened prior to the originating MS requesting to set up a PTT call. To further reduce the delay, the user may begin speaking prior to completion of the call setup. The speech is stored and is conveyed to a called MS when the call is setup. If the call does not get setup or a user of the called MS is not present, the stored speech may be conveyed to the called MS as a voice message. The stored speech, or new speech, may also be used as an announcement of a call instead of the typical “beep” or “chirp.”

A network combining wireless and wired elements is described, using a multi-slot modular mesh node to house diverse transceiver elements (e.g. IR, Wi-Fi, Powerline). A radio agnostic tree based mesh network is formed, based on what type of wireless links are formed on the uplink and downlink of the backhaul and what type of radios are used for the Access Points AP. In addition to servicing IP based clients (e.g. Wi-Fi, WiMax, Bluetooth), the modular mesh nodes APs may also serve as receivers/collectors for low cost chirp devices. The method of transport is standard IP based packets yet security is inherent in this chirp-based implementation: only mesh nodes are privy to the routing tables that indicate that packet addresses are not IP. Multiple methods to obfuscate packet flow are presented. An organic approach to providing category/class based form of data type identification is proposed, to support a (dynamic) M2M Social Network Applications in-device discovery, registration and control are presented.

The present invention relates to a method for optical fiber transmission which can increase a transmission distance. A first optical fiber having dispersion is first provided. An optical signal is next supplied to the first optical fiber so that the optical signal is compressed on the time axis as propagating in the first optical fiber. In the case that the dispersion is normal dispersion, for example, prechirping is performed so that the optical signal has down-chirp. A compressed optical signal output from the first optical fiber is supplied to an optical device having a saturated gain. According to this method, the transmission distance can be increased by the effective combination of compression of the optical signal and waveform shaping by the optical device.

An optical coherent detector that employs an interleave-chirped arrayed waveguide grating (AWG). The AWG has a periodic chirp pattern that enables the AWG to function as an optical 90-degree hybrid. If the AWG is implemented using a birefringent material, then the AWG can also function as a polarization demultiplexer. In one embodiment, the AWG is designed to simultaneously function as a wavelength demultiplexer, a polarization demultiplexer for each wavelength-division-multiplexed (WDM) signal component, and a 90-degree hybrid for each polarization-division-multiplexed component of each WDM signal component.

This disclosure presents a non-contact precision optical device, including methods for measuring distances to an arbitrary target and various configuration geometries, for using polarization maintaining (PM) optical fiber components in a polarization diplexing scheme to construct a version of a dual chirp coherent laser radar that is immune to environmental effects.

A locator system for tracking the location of individuals in a defined environment is disclosed. The system comprises at least one user identifier, at least one reader, at least one locator station and an identification server. The user identifier includes a long-range transmitter adapted to transmit an identification signal and a short-range passive component having identification information. The reader is adapted to receive the identification signal from the long-range transmitter. The locator station is adapted to read the identification information from the short-range passive component. The identification server is adapted to communicate with the reader and the locator, and has a database associating the identification signal of the long-range transmitter and the identification information of the short-range passive component with a particular user. The identification signal from the long-range transmitter may be an intermittent chirp. The long-range transmitter and the short-range passive component may be mounted on an identification tag, which may be attached to a wrist strap for securing the identification tag to a user's wrist.

In accordance with the invention, an optical communication system is provided with one or more automatic dispersion compensation modules. Each module has an adjustable dispersion element, a data integrity monitor and a feedback network whereby the monitor adjusts the dispersion element to optimize system performance. In a preferred embodiment the dispersion compensating modules comprise chirped fiber Bragg gratings in which the chirp is induced in the grating by passing a current along distributed thin film heaters deposited along the length of the fiber. The magnitude of the applied current determines the dispersion of the grating. A data integrity monitor is configured to sense the integrity of transmitted data and to provide electrical feedback for controlling the current applied to the grating.

A tree-shaped mesh network is discussed which uses a mesh of wireless nodes that form a tree shaped network with one root node having a connection to an external network; chirp clients; and wireless network clients. Chirp clients comprise low cost chirp devices wherein said low cost chirp devices transmit short duration messages wherein transmission of said short duration messages are scheduled at preset transmission intervals. At least one wireless node of the mesh of wireless nodes is a designated chirp-aware node wherein said chirp-aware node sets the preset transmission intervals for chirp client communication by broadcasting a beacon prior to transmission by chirp clients and said chirp-aware node further comprises a bridge between the short duration messages and IP based devices wherein said bridge includes a wireless receiver to receive the short duration messages and is connected to said external network. The short duration messages are encapsulated into action frames, for onward transmission to other chirp aware routers. Each wireless node further comprises two logical radios and a service radio wherein each wireless node uplink and downlink operates on distinct non-conflicting frequencies. The wireless network clients communicate with the wireless nodes using node service radios.

A method for forming planar-waveguide Bragg grating in a curved waveguide comprises: forming a long chirped planar-waveguide Bragg grating in an Archimedes' spiral such that a long length of the waveguide can fit in a small chip area where the grating is formed in the curved waveguide; using periodic width modulation to form the planar-waveguide Bragg grating on the curved waveguide, and where the formation of the periodic width modulation occurs during the etching of the waveguide core; using rectangular width modulation to create Bragg gratings with a higher order than 1^st order to allow a larger grating period and larger modulation depth, using waveguide width tapering while keeping the width modulation period constant to introduce chirp to the planar-waveguide Bragg grating where the index of refraction is a function of waveguide width, by applying a specific width tapering to create a desired arbitrary chirp profile.