290 results about "Offset calibration" patented technology

A personal base station configured to connect to the Internet and establish a small area of wireless coverage including means for controlling interference with neighboring personal base stations using a timeslot management mechanism. Timeslot management mechanisms include timeslot interference detection, timeslot power reduction, timeslot allocation, timeslot offset calibration, and timeslot synchronization management that minimizes the number of frequencies required to control inter-cell interference between neighboring personal base stations.

A multi-dimensional sensor, a magnetometer or accelerometer, is calibrated based on the raw data provided by the sensor. Raw data is collected and may be used to generate ellipse or ellipsoid parameters, for a two-dimensional or three-dimensional sensor, respectively. An offset calibration factor is calculated based on the raw data, e.g., the determined ellipse or ellipsoid parameters. A sensitivity calibration factor is then calculated based on the offset calibration factor and the raw data. A non-orthogonality calibration factor can then be calculated based on the calculated offset and sensitivity calibration factors. Using the offset, sensitivity and non-orthogonality calibration factors, the raw data can be corrected to produce calibrated data.

The invention provides a signal processing semiconductor integrated circuit of the direct conversion system, which includes a dummy amplifier having the same circuit configuration as a low noise amplifier being the first stage amplifier, in which the DC offset calibrations on the subsequent stage amplifiers are carried out during shifting into the reception mode in a state that the low noise amplifier is deactivated and the dummy amplifier is activated. Thereby, the invention achieves to suppress generation of the DC offsets resulting from the leakage noises of the local oscillator during shifting into the reception mode, and to enhance the reception sensitivity.

A novel method and apparatus for calibrating DC offsets in a direct conversion receiver. The present DC offset calibration method and apparatus comprises a direct conversion receiver equipped with a frequency shifter means and a DC offset measurement and correction technique. In accordance with the present invention, DC offsets are calibrated in direct conversion receivers through an inventive method including two steps: a DC offset measurement step and a DC offset correction step. In the DC offset measurement step the frequency of a local oscillation signal (typically generated by a voltage-controlled oscillator (VCO)) is shifted by a selected frequency shift value during the inactive time intervals of the receiver. DC offsets are measured while the frequency of the down-conversion oscillation signal is shifted by the frequency shift value. Before the inactive time interval expires, the frequency of the down-conversion oscillator signal is shifted back to its original value. In the DC offset correction step of the present invention incoming signals are corrected using a correction means that removes the DC offset measured during the DC offset measurement step.

A calibration algorithm is provided for calibrating a machine vision system including a color camera, a framegrabber and an illumination source wherein subsequently acquired images are processed on a pixel-by-pixel basis. After framegrabber offsets are measured to obtain initial or offset calibration data, the camera is pointed at a target monotone patch of known reflectance such as pure white and the camera outputs for red, green and blue are determined while observing the monotone patch to obtain spatial calibration data. The gain for each of the output channels of the color camera is automatically determined from the initial calibration data. Applying the three gain factors to a subsequent image on the pixel-by-pixel basis allows one to end up with a color-corrected image without incurring any time performance penalty. At any time during an inspection process, a small area of white reflectance can be observed. The resulting dynamic white calibration data is used to correct for any medium to long term temporal variation in imaging conditions.

System and method of calibrating the DC offsets of alternate comparators in an ADC in the background based on the digital outputs of the ADC. In parallel with A/D conversion of a plurality of samples, the calibration logic uses two counters to count the occurrences of the ADC outputs that represent samples falling in a first analog range and a second analog range, respectively. The two ranges are symmetric about the MSB reference voltage and in combination cover the nominal voltage range of the bit. The DC offset is derived based on a ratio of the difference between the two counts and a sum of the two counts. The calibration logic may alternately calibrate the comparators. Each comparator may be calibrated successively based on various bits associated therewith.

A system and method for testing and calibrating integrated sensor devices that improves the manufacturing test throughput of the devices. The system includes a tester, a temperature controller, and at least one probe station including a thermal chuck. The chuck can be heated to specified temperatures to achieve variable heating of a wafer, PCB, or pallet disposed thereon. The temperature controller adjusts the temperature of the chuck to a first specified level. The tester performs at least one first measurement of the output offset of each integrated sensor embodied as a die on the wafer, or as a device on the PCB or pallet. Next, the temperature controller adjusts the temperature of the chuck to a second specified level, and the tester performs at least one second measurement of the output offset of each integrated sensor at the second temperature level. The offset temperature coefficient (OTC) of each sensor is calculated based upon the output offset measurements performed at the first and second temperature levels, and optimal settings for calibrating the respective sensors are determined based upon the calculated OTC values. After the temperature of the chuck is brought back down to the first specified level, the tester programs the output offset calibration settings into each sensor.

The invention relates to an infrared two-point non-uniform calibrating method based on a frame black body field diaphragm, belonging to the field of infrared thermal imaging. The method comprises the following steps of: arranging an automatically-telescopic frame black body field diaphragm on a diaphragm of an infrared thermal imager and performing two-point calibration under a frame to obtain a gain calibration factor and an offset calibration factor of a detection unit under the coverage of a frame black body; acquiring f frames of initially-calibrated images respectively on two scenes to obtain f-1 groups of inter-frame displacement parameters on every scene; and acquiring calibration parameters of f-1 groups of images with inter-frame displacement on an internal detection unit by adopting an algebraic method, and averaging the frames to obtain finial calibration matrixes G and 0 for calibrating the entire field of a subsequent infrared video. The method has the advantages of rapidness, self-adaption and system miniaturization, and can be applied to the fields of designing, production and manufacturing of refrigerating and non-refrigerating infrared focal plane detector thermalimaging systems, satellite infrared thermal imaging systems, infrared alarm systems, scientific researches and the like.

A limit-cycle oscillation (LCO) based switch-mode power supply (SMPS) response evaluation provides an effective mechanism for determining the characteristic response of an SMPS during normal operation of the SMPS. LCOs are induced in the SMPS loop by introducing a non-linearity in the loop, for example, decreasing the resolution of a pulse-width modulator that controls the SMPS switching circuit. The frequency and amplitude of the LCOs are determined and used to evaluate the characteristic response of the SMPS. In order to produce symmetric LCOs, which are more easily modeled, a zero-offset calibration circuit adjusts values provided to the pulse-width modulator, so that each value introduced during calibration is at the midpoint of a resolution cell. The frequency can be measured by counting between zero-crossings of the LCOs and the amplitude measured by capturing the LCO values immediately prior to each zero-crossing of a first difference of the LCO samples.

The invention provides a method and a dehvice for the zero point calibration of a gas pressure sensor, which comprises the steps that: when a brake cylinder is released, the pressure value of the brake cylinder is obtained; the releasing process is judged to be normal or abnormal according to the time the pressure value is obtained and according to the pressure value; when the releasing process isnormal, the pressure value of the brake value is judged to whether reach zero or not; when the pressure value of the brake reaches zero, the pressure value obtained currently is compared with a pre-stored composite error nominal value; when the pressure value obtained currently is smaller than or equal to the composite error nominal value, the pressure value obtained currently is regarded as a zero point correct value; and the zero point of the gas pressure sensor is calibrated according to the zero point correct value. The method and the device can solve the problem of zero point drift and have simple operation and lowered workload and calibration cost.

Systems, processes, and techniques for calibrating an onboard sensor of a vehicle are presented here. The vehicle has a control system that is capable of performing at least some of the tasks related to the calibration procedure. An exemplary methodology collects vehicle status data and obtains navigation map data during operation of the vehicle. A current calibration factor is calculated for the onboard sensor, based on the collected vehicle status data and the obtained navigation map data. More specifically, the vehicle status and navigation map data can be used to determine when the current conditions are suitable for performing calibration. When the current conditions are satisfactory, the calibration factor is calculated. Thereafter, the onboard sensor can be calibrated in response to the current calibration factor.

A process of data calibration and correction is disclosed that utilizes feedback from a temperature sensor of an x-ray detector to isolate or otherwise select an appropriate calibration or correction map that is specific to the temperature of the x-ray detector during data acquisition. The method is also designed to take into account changes in power transients of an x-ray detector between the acquisition of imaging data and the acquisition of offset data. The method is particularly applicable in optimally selecting and applying gain correction, conversion factor, bad pixel, and offset calibrations.

The invention relates to an ATM self-service business hall behavior analysis method based on depth information. Behavior analysis based on common two-dimensional cameras is adopted in the prior art, and the situation that targets cannot be accurately positioned exists. According to the ATM self-service business hall behavior analysis method, firstly, binocular cameras are adopted for serving as acquisition equipment for the depth information, background modeling is carried out on depth maps, a Gaussian mixture model of each pixel is learned and updated, and background distribution is determined; secondly, the probability value of each pixel in each new depth map is worked out, and clustering segmentation is carried out on a front depth map according to the DENCLUE algorithm; finally, pixels in each human body region in each camera are projected onto the ground, association of projected targets is carried out by using multi-camera offset calibration, and therefore target detection under the multiple cameras is achieved under a global coordinate system. The depth information is used and background modeling of RGB information is combined, so that the stability of target detection is greatly improved, and a good basis is provided for following behavior analysis.

A mixer for a radio transceiver includes a commutating mixer switch having a first differential input port coupled to a DC offset cancellation path. The first differential input port of the mixer switch includes a first terminal coupled to a first end of a first resistor and a second terminal coupled to a first end of a second resistor. Second ends of the first and second resistors are configured to receive a differential input signal. The DC offset cancellation path may provide a resistively coupled DC calibration signal for reducing the magnitude of DC offsets that may be present at the input of the mixer switch. The concept can be used for either image or non-image reject mixers.

A background-calibrated comparator and a background-calibrated flash analog-to-digital converter are disclosed for using in mixed-signal integrated circuit design in particular on the high-speed analog-to-digital converter circuit. Without affecting the operation of the comparator, the disclosure is directed at reducing the unpredictable input offset voltage originated from the variation of process parameters and environmental factors. The background-calibrated comparator includes a random chopping comparator, a calibration processor, and a random sequence generator. The background-calibrated flash analog-to-digital converter (ADC) includes a background-calibrated comparator array together with a reference voltage generator, a thermometer code edge detector, and a set of digital encoders.

DC offset is compensated for in an analog front end (AFE) circuit having an amplifier and an analog-to-digital converter (ADC). First data processed by the ADC are low pass filtered and estimated DC offset data of the ADC are obtained in ADC DC offset calibration mode. Second data processed by the ADC and the amplifier are low pass filtered, and a first DC offset of the ADC are substantially removed from the filtered second data by subtracting the estimated DC offset data from the filtered second data, thereby obtaining second compensated DC offset data of the amplifier in an amplifier DC offset calibration mode. The second compensated DC offset data is iteratively improved and first compensated DC offset data of the amplifier are obtained. The first compensated DC offset data are transformed into an analog signal, and the analog signal is subtracted from an input signal of the amplifier during operation mode.

The invention discloses a dynamic comparator with high speed and low kick noise, which belongs to the field of analog integrated circuits. Its structure includes: pre-amplification stage, current compensation branch for suppressing kickback noise, positive feedback regeneration stage composed of N-channel transistor and P-channel transistor cross-coupling unit, current between pre-amplification stage and positive feedback regeneration stage A control unit, a reset control unit, an offset calibration unit, and an inverter output driver stage. The two current compensation branches that suppress the kickback noise compensate the current attenuation of the main channel to ensure a constant working current of the input pair tube, thereby suppressing the influence of the kickback noise on the input signal, thereby increasing the size of the input pair tube and reducing offset voltage, increasing the response speed. Compared with the traditional comparator, the invention satisfies the requirement of high speed and low power consumption, and exhibits excellent kickback noise suppression ability.

An embodiment of the invention relates to the technical field of automatic driving, and discloses a vehicle, and a method and a system for automatically calibrating zero offset of a steering wheel ofthe vehicle. The method includes judging whether the vehicle is in straight driving states in current sampling time intervals or not; determining that the current sampling time intervals are current calibration time intervals if the vehicle is in the straight driving states, and acquiring steering angles of the steering wheel of the vehicle when the vehicle is in the straight driving states; acquiring historical zero offset calibration results; calculating real-time zero offset calibration results of the steering wheel of the vehicle according to the historical zero offset calibration resultsand zero offset calibration results, which correspond to the current calibration time intervals, of the steering wheel of the vehicle. The steering angles are used as the zero offset calibration results, which correspond to the current calibration time intervals, of the steering wheel of the vehicle. The vehicle, the method and the system in the embodiment of the invention have the advantages thatthe zero offset of the steering wheel of the vehicle which is currently automatically driven can be automatically calibrated by the aid of the method and the system, and the zero offset measurement accuracy of the steering wheel of the vehicle can be improved.

A new method for determining an actual steering wheel angle is provided that does not require re-calculation of a steering center upon each ignition of the vehicle. Accordingly, the vehicle dynamic controller may be activated very quickly after ignition, while a less costly relative steering wheel angle sensor may be employed.

The present technique provides for the spectral calibration of the detector elements of a CT detector using one or more offset calibration phantoms. The offset phantoms provide greater coverage of the detector elements as well as spectral response data associated with penetration lengths ranging in length from a minimum chord of the phantom to the diameter of the phantom. The spectral response as a function of penetration length can be obtained for each detector element by comparing the fitting of each projection view to the corresponding measured projection view over all view angles. The fitting information may then be employed to derive the coefficients of the spectral response curve for each detector element, which may in turn be employed to provide rapid correction of the spectral response for each element.