73 results about "Ambiguity problem" patented technology

Common path frequency domain optical coherence reflectometry / tomography devices include a portion of optical fiber with predetermined optical properties adapted for producing two eigen modes of the optical radiation propagating therethrough with a predetermined optical path length difference. The two replicas of the optical radiation outgoing from the portion of the optical fiber are then delivered to an associated sample by an optical fiber probe. The tip of the optical fiber serves as a reference reflector and also serves as a combining element that produces a combination optical radiation by combining an optical radiation returning from the associated sample with a reference optical radiation reflected from the reference reflector. The topology of the devices allows for registering a cross-polarized or a parallel-polarized component of the optical radiation reflected or backscattered from the associated sample. Having the optical path length difference for the two eigen modes of the optical radiation (which is an equivalent of an interferometer offset in previously known devices) differ from the reference offset in the devices of the present invention allows for relieving the requirements to the spectral resolution of the FD OCT engine and / or data acquisition and processing system, and substantially eliminates depth ambiguity problems.

Common path frequency domain optical coherence reflectometry / tomography devices with an additional interferometer are suggested. The additional interferometer offset is adjusted such, that it is ether less than the reference offset, or exceeds the distance from the reference reflector to the distal boundary of the longitudinal range of interest. This adjustment allows for relieving the requirements to the spectral resolution of the frequency domain optical coherence reflectometry / tomography engine and / or speed of the data acquisition and processing system, and eliminates depth ambiguity problems. The new topology allows for including a phase or frequency modulator in an arm of the additional interferometer improving the signal-to-noise ratio of the devices. The modulator is also capable of substantially eliminating mirror ambiguity, DC artifacts, and autocorrelation artifacts. The interference signal is produced either in the interferometer or inside of the optical fiber probe leading to the sample.

Keyboards, keypads and other data entry devices can suffer from a keying ambiguity problem. In a small keyboard, for example, a user's finger is likely to overlap from a desired key to onto adjacent ones. An iterative method of removing keying ambiguity from a keyboard comprising an array of capacitive keys involves measuring a signal strength associated with each key in the array, comparing the measured signal strengths to find a maximum, determining that the key having the maximum signal strength is the unique user-selected key, and maintaining that selection until either the initially selected key's signal strength drops below some threshold level or a second key's signal strength exceeds the first key's signal strength.

A clock recovery circuit and a method for reduced electromagnetic emission (EMI) and increasing an attainable clock frequency includes a spread spectrum clock (SSC) generator that receives an input clock signal and generates a frequency-modulated clock signal, and a zero-delay buffer circuit that receives and buffers said modulated clock frequency signed to generate an output clock signal. The frequency-modulated clock signal and the output clock signal are phase-aligned such that there is no phase difference between the output clock signal and the modulated frequency clock signal. The clock recovery circuit also includes a delay-locked loop (DLL) circuit that reduces related art jitter and skew characteristics, and a phase detector circuit that eliminates phase ambiguity problems of a related art phase detector.

A method for detecting an intruder in a protected space that uses a microwave frequency sensor to determine an accurate distance measurement to the intruder. The accurate distance measurement reduces the false alarms typically associated with microwave frequency sensors due to motion outside the protected space and vibration within the protected space. The motion detector transmits three microwave frequency signals of different frequencies in order to eliminate an ambiguity problem when determining the accurate distance measurement. The accuracy of the intruder distance measurement may be determined with greater resolution by reiteratively transmitting and evaluating microwave frequency signals of different frequencies. The motion detector of the present invention may include a PIR sensor. The accurate distance measurement allows the motion detector to precisely set signal threshold levels for the microwave frequency detector and the passive infrared detector to reliably detect an intruder while discriminating against an animal or other moving object.