170 results about "Time drift" patented technology

A generic navigation satellite system (GNSS) signal receiver having a fast time to first fix by calibrating a low power always-on real time clock (RTC). The receiver includes an RTC calibrator having a fraction calculator and a time expander. Before the receiver is powered off, the fraction calculator uses the fine resolution of GNSS time for determining a time fraction for RTC time. When the receiver is powered back on, the time expander uses an estimate of RTC time drift during the time that GNSS receiver had power off and the time fraction for calibrating and increasing the resolution of the RTC time for an RTC time tick. A signal navigation processor uses the calibrated RTC time for assisting a first fix with code phase search, integration time periods, resolution of epoch integer and / or location-in-space of GPS satellites.

The invention relates to a precise control method of an atom spin SERF (Self-Exchange Relaxation-Free) state for stabilizing an atom spin device, which comprises the following steps that firstly, a precise equation is established for the atom spin SERF state, and a modulation method is adopted to measure the atom spin polarizability to establish a control target; then a control system model as precise as possible is established on the basis of an SERF model, and a parameter identification method is adopted to estimate unknown parameters of the model; and finally, according to the control target, a special structure design control law of the established model is fully used, i.e. the switching time, frequency, orientation and power of laser and the switching time of a modulation magnetic field are optimized, and the atom spin SERF state is precisely controlled in real time in accordance with a quantum control algorithm. By using the precise control method, the atom spin relaxation time is increased, and the problem of instability of scale factors of atom devices such as an atom spin gyroscope and an atom magnetometer based on the atom spin SERF effect is solved. The precise control method can be used for improving the long-time drift precision and the low-frequency sensitivity based on the SERF atom spin device.

The invention relates to a single-shaft rotary type inertial navigation system. The invention further relates to a special error self-compensation method of the single-shaft rotary type inertial navigation system. The single-shaft rotary type inertial navigation system comprises an indexing mechanism and a single-shaft rotary type inertial navigation system inertial measurement unit, wherein the single-shaft rotary type inertial navigation system inertial measurement unit is mounted on an inertial measurement unit mounting plane; the inertial measurement unit mounting plane and the indexing mechanism are connected together; coordinate axes of the single-shaft rotary type inertial navigation system inertial measurement unit are vertical to each other two by two; each coordinate axis is provided with a gyroscope and an accelerometer. According to the single-shaft rotary type inertial navigation system disclosed by the invention, real-time drifting estimation is implemented by adopting a manner of realizing an adjustable inclined angle of an IMU (Inertial Measurement Unit) mounting plane; the inclined angle can be dynamically readjusted at intervals, so as to further improve the compensation effect of the system; a previous process of recalibrating in a laboratory with a high-precision inertial navigation testing rotary table can be finished in field in a use process, and the guarantee and maintenance costs of an operation period of the inertial navigation system are greatly reduced.

A method and apparatus for synchronizing a real time clock of a slave computer with a real time clock of a master computer. The method includes the steps of: calculating a first time drift value between the real time clock of the slave computer and the real time clock of the master computer, calculating a second time drift value between the real time clock of the slave computer and the real time clock of the master computer, calculating an average time drift value between the real time clock of the slave computer and the real time clock of the master computer using the first time drift value and the second time drift value, and adjusting the real time clock of the slave computer using the average time drift value.

The invention discloses a method for improving accuracy of a geomagnetic parking stall detector. The method includes: by collecting sample data of a background magnetic field, calculating and recording benchmark data of the background magnetic field as reference standards; respectively determining calculated weight values in three axial directions according to stability of the sample data, collected by a triaxial magnetoresistive sensor, of the background magnetic field in three axial directions; turning off a wireless communication module when reading data of the triaxial magnetoresistive sensor, and storing the data into a buffer queue; calculating magnetic field changes for the data in the buffer queue, performing median filtering, and performing parking stall state determination according to changes of the magnetic field data; calibrating the benchmark data of the background magnetic field under the condition of free parking stalls; uploading the parking stall information and battery level information through the wireless communication module prior to entering the sleep state; waking through an RTC (real-time clock) in a timed manner, continuing executing from the step 3, and so on. Compared with the prior art, the method has the advantages that influence caused by temperature drift compensation and time drift of the sensor on parking stall determination accuracy can be restrained effectively, and the method is higher in adaptability, lower in cost and the like.

The invention provides a metal-oxide gas sensor array concentration detecting method based on drift compensation. According to the method, the independent component analysis is utilized, the influence of abnormal values caused by the environment temperature, the environment humidity and environment factors to the drifting regulation and the drifting quantity estimation is shielded, the law that a independent concentration component changes along with the time drifting under the condition of base line responses is found out, subsequently, and when the concentration detection treatment on a gas sample is subjected to the concentration detection treatment by a metal-oxide gas sensor array, the drifting quantity of the concentration independent component is estimated by using the law that the independent concentration component changes along with the time drifting under the condition of the base line responses, so as to carry out drifting compensation on the independent concentration component in concentration detection response data; and the prediction calculation is carried out through using a concentration prediction function by virtue of the independent concentration component subjected to the drifting compensation in the concentration detection response data, so as to obtain a sensitive gas concentration detection result. The precision in estimating the drifting law and the drifting amount can be effectively improved, and the accuracy of concentration detection of the metal-oxide gas sensor array is ensured.

A system for measuring differences in a physical variable, such as temperature or voltage, by utilizing predictable behavior in the relative drift over time of reference curves representative of offset, and other measurement parameters for various circuit elements. In an initial calibration mode, the system records several reference curves, correlating ambient condition to offset, and, optionally, other parameter measurements acquired from circuit elements. These reference curves representing drift behavior, among electrical components, can be updated for time drift at a single, current arbitrary ambient temperature, the measurements for which can be obtained quickly and applied as a time drift correction to the reference curves, without interrupting normal system operation, to provide a compensated difference measurement between the different values of the physical variable. Additionally, the system dynamically tracks cumulative system errors, in order to calculate optimal system resolution, based upon current operating conditions.

The invention is suitable for the technical field of audios and videos, and provides a method and a device for processing play abnormality of an audio stream, a computer device and a computer readablestorage medium. The method comprises the steps of obtaining audio frame data in a cache; parsing decoding parameters in the audio frame data to obtain related audio data and recording the time stampof the first frame of the audio frame data; decoding and rendering the parsed audio frame data; obtaining the actual audio rendering time based on the related audio data and the time stamp of the first frame of the audio frame data; obtaining a real-time code stream playback time drift based on the actual audio rendering time; judging whether the audio frame data are abnormal based on the real-time code stream playback time drift; and when the judgment result is affirmative, starting and resetting an audio processing operation. According to the embodiment, the problem of sound interruption andstop caused by factors such as code stream shaking, signal instability or code stream hop can be processed efficiently, the stability of audio play is improved, and the conditions of unsmooth audio play are reduced.

The invention discloses an intelligent pressure transmitter, which is provided with a digital temperature sensor and a pressure sensor. Temperature signals and pressure data can be acquired in real time, the pressure data are converted by an A / D (analog / digital) conversion module and then transmitted to a microcontroller for processing together with the temperature signals, so that temperature compensation, zero drift compensation and nonlinear rectification are realized for the pressure sensor. The intelligent pressure transmitter can overcome the shortcoming of zero drift of a traditional pressure transmitter, and has an excellent zero drift compensation characteristic and a fine time drift suppression characteristic.

The invention discloses a time synchronizing method for a wireless sensor network, and belongs to the technical field of wireless sensor networks. According to the technical scheme of the invention, the network comprises a master node and n slave nodes, the slave nodes perform relative clock drift estimation, and master and slave node clock synchronization is performed between the master node and the slave nodes by exchanging synchronization messages in order to compensate for a clock deviation caused by a crystal oscillator, so that local clocks of the slave nodes are regulated to realize accurate synchronization of a main node clock. By adopting the time synchronizing method, time drift caused by the crystal oscillator can be suppressed effectively, and the clock synchronizing accuracy among network nodes is increased.

The invention discloses an unmanned vehicle navigation positioning precision correcting method based on GNSS and VO combination. The method comprises the steps of (1) lane line detection based on monocular vision; (2) positioning precision optimization of a monocular vision mileometer; and (3) correcting the positioning precision of a GNSS / VO combined navigation system. According to the invention,the lane line auxiliary visual mileometer is used and combined with GNSS positioning to improve the reliability of a vehicle positioning system. The GNSS / VO has strong complementary characteristics,the GNSS can obtain a long-time stable positioning result, and the VO can obtain short-term high-precision positioning data. The difference of the position measurement values is filtered and calculated by utilizing the two sensors. The error of a VO system is corrected by using an estimated value of the VO system error, so that the purpose of limiting the long-time drift of VO data by utilizing the GNSS data is achieved.

The invention discloses a fiber grating demodulating system with real-time reference, which comprises a light path part, a circuit part, an upper computer and a software program. A reference light path with a precise Fabry-Perot cavity is in parallel connected through a coupler and an isolator on the basis of an original demodulating system based on a Fabry-Perot tunable filter demodulation method, and the measurement result of a measured light path can be corrected in real time through the measurement value of the reference light path, so that demodulation accuracy can be enhanced; two photoelectric signals are acquired and encoded by an underlying hardware circuit and then transmitted to the upper computer, a peak value position is extracted by adopting a Gaussian fitting algorithm on the upper computer, and real-time reference is carried out on the measured light path by utilizing the standard value of the reference light path. The method disclosed by the invention effectively solves the problem of demodulating accuracy degradation caused by the principle errors, namely a time-drift error, a temperature drift error, a hysteresis error, and the like, of a Fabry-Perot tunable filter, thereby providing a new exploring direction for the construction of the fiber grating demodulating system disclosed by the invention.

The invention provides a piezoresistive sensor circuit capable of automatically correcting zero-bias. The invention provides an interface circuit capable of automatically correcting the zero point bias voltage of a piezoresistive sensor so that the measuring results can be more precise. When a piezoresistive sensor system is electrified, a successive approximation principle is utilized for automatically correcting the output of the piezoresistive sensor system, the unchanged correction voltage can be maintained for a long time, and in addition, the time drift problem does not exist. The invention overcomes the defects of the existing piezoresistive sensor circuit, and has the characteristic of automatically correcting the output voltage of the sensor.

The invention discloses a transmission cavity frequency regulator capable of carrying out frequency stabilization on multiple beams of laser, and relates to the field of laser frequency stabilization. The abstract attached diagram is a structure diagram of the transmission cavity frequency regulator capable of carrying out frequency stabilization on four beams of laser. The frequency regulator is composed of a transmission cavity (11), a reference laser (1), four lasers to be stabilized with different wave lengths (2, 3, 16 and 17), lenses (4, 5, 6, 18 and 19), reflector mirrors (7, 10, 20 and 21), spectroscopes (8, 9, 22 and 23), a piezoelectric controller (12), a calculation controller (13), a temperature controller (14) and a photoelectric detector (15). The transmission cavity frequency regulator capable of carrying out frequency stabilization on the multiple beams of laser has the advantages of being capable of simultaneously locking the frequencies of the multiple beams of laser, restraining long-time drifting of the frequencies of the multiple beams of laser, being convenient to use, saving space and lowering cost, and can be widely applied to the fields needing laser frequency stabilization such as laser physics, frequency standards and quantum information.

The invention discloses a time synchronization method for a fault indicator of a transient wave record type, and the method comprises the steps that a convergence unit broadcasts a synchronization beacon frame to each collection unit for synchronization; each collection unit transmits a data frame comprising a synchronization byte to other collection units and the convergence unit, and each collection unit monitors the data frames of other collection units, and marks the data frames with the synchronization bytes; two collection units which transmit the data frames at first carry out the synchronization of local time with the collection unit which transmits the data frame at last according to the relative time drift and relative initial time difference; the convergence unit carries out thesynchronization of all data frames according to the obtained time difference. The method achieves the local synchronization of the collection units, and achieves the post-synchronization of the dataframes in the convergence unit.

The invention provides a plant differential metabolite fast-screening method based on UPLC-QTOF. The method comprises acquiring information of chemical constituents in the plant through an UPLC-QTOF modern analytical technology, extracting substance information through a non-target metabolic profile analysis technology, carrying out chromatographic peak extraction and in-source pyrolysis molecular fragment clustering, carrying out between-sample time drifting correction through a dynamic planning method, carrying out between-sample substance registration according to a self-adaptive network link method and screening sample different metabolites through statistical analysis.

A generic navigation satellite system (GNSS) signal receiver having a fast time to first fix by calibrating a low power always-on real time clock (RTC). The receiver includes an RTC calibrator having a fraction calculator. The RTC calibrator may also include a time expander. Before the receiver is powered off, the fraction calculator uses the fine resolution of GNSS time for determining a time fraction for RTC time. When the receiver is powered back on, the time expander uses an estimate of RTC time drift during the time that GNSS receiver had power off and the time fraction for calibrating and increasing the resolution of the RTC time for an RTC time tick. A signal navigation processor uses the calibrated RTC time for assisting a first fix with code phase search, integration time periods, resolution of epoch integer and / or location-in-space of GPS satellites.

The invention provides an apparatus and method for measuring photon time information. The apparatus comprises a current detection circuit and a processing circuit. The current detection circuit is used for connection with a photoelectric sensor for detecting initial signals output by the photoelectric sensor and generating corresponding detection signals. The input end of the processing circuit is connected with the output end of the current detection circuit, and the processing circuit is used for determining arrival time of high-energy photons detected by the photoelectric sensor according to the detection signals, according to the detection signals, estimating a time drift amount and correcting the arrival time based on the time drift amount. According to the method and apparatus provided by the embodiments of the invention, the time drift amount is estimated, the arrival time is corrected based on the time drift amount, a time measurement error caused by a dark event can be corrected in such a way, and a high-precision time measurement result can be simply and conveniently obtained.

A system of measuring pH of a solution having a calibration device to counteract time-drift effect. The calibration device of the system adjusts a compensation voltage to zero a measuring voltage of a first sensor and only respond to time-drift voltage of the first sensor. The calibration device has a differential operation amplifier receiving measuring voltages from the first sensor and a second sensor of the system to eliminate the time-drift voltages of the first and second sensors, thereby achieving calibration of the time-drift effects.

The invention provides an optimization method of software timers. The method includes the steps that a first timer array and a second timer array are created; total run time is defined and recorded as T1, time required for overtime processing of all timer instance objects at every moment is recorded as T2, and T1 and T2 are initialized to be zero; after waiting for a time slice, 1 is added to the total run time T1, and obtained time is recorded as T1'; the timer instance objects are added to chain table array elements of the first timer array according to chain table index numbers, overtime of the timer instance objects is detected, overtime T3 is recorded, and an index moment is generated; the timer instance objects corresponding to the index moment are added to chain table array elements of the second timer array according to the index moment; an overtime callback handler function is executed in the second timer array in a loop mode, and then the corresponding timer instance object is deleted until all the timer instance objects are executed. According to the method, operation efficiency of the timer instance objects is improved, the occupancy rate of a CPU is greatly reduced, time drift compensation is conducted on the timers, and timing accuracy of the timers is improved.

The invention is applied to the technical field of audios / videos, and provides an audio stream flow velocity error processing method and apparatus, a computer apparatus and a computer readable storagemedium. The method comprises the steps of obtaining audio frame data in a cache; analyzing the audio frame data to obtain a timestamp for a first frame of the audio frame data; according to a difference value between the timestamp for the first frame and a timestamp of an audio frame entering to be cached newly when audio playing is started, obtaining an initial bit stream time drift of the audioplaying; performing decoding and rendering on the audio frame data, and calculating a practical audio rendering time; according a difference value between the practical audio rendering time and a timestamp of an audio frame entering to be cached newly at present in an audio frame data decoding process, obtaining a real-time bit stream playing time drift; and when the real-time bit stream playingtime drift is not consistent with an initial code stream time drift, accelerating or lowering an audio playing speed. The problem of cache up-down overflow due to a front-end transmission precision error in the audio playing process is eliminated, and the product stability is improved.

An electronic circuit for ion sensor with the body effect reduction includes a bridge-type floating source circuit provided with an input terminal, an output terminal reflecting the change in the potential dependent on ion concentration, and an ion-sensitive field effect transistor (ISFET) wherein one terminal of the ISFET is coupled with the output terminal; a current mirror for providing a current to the bridge-type circuit; a third transistor for receiving the operating current provided by the current mirror, identical to the current provided to the ISFET; a differential amplifying circuit, wherein one input terminal of the amplifying circuit is input with a reference voltage, and the other input terminal is coupled with the output of the bridge-type readout circuit; and a third amplifier to generate a differential output voltage compensated for the body effect, temperature and time drift effects.

An optical phase modulator having a reduced time drift of an electro-optical response is disclosed. An optical waveguide exhibiting the electro-optic effect includes two serially coupled portions having opposite time drifts of magnitudes of their respective electro-optical responses. As a result, a time drift of an overall electro-optical response of the optical phase modulator is lessened.

The invention discloses a method of controlling a slave station servo driver synchronization master station. The method of controlling a synchronization master station comprises the following steps: after a second core detects a SYNC signal, acquiring the current value of a CNT signal, wherein the CNT signal is the real-time count value of PWM triangular carriers generated in a PWM interrupt processing module; comparing the current value of the CNT signal with K / 2, wherein K is a PWM triangular carrier count value corresponding to a set allowable time drift value between the starting moment of PWM interrupt and the rising edge of the SYNC signal; when the current value of the CNT signal is greater than or equal to K / 2, judging the counting direction, and setting the value of CNT to an interrupt value or an integer value which is a set threshold range from the interrupt value according to the counting direction; and making the PWM interrupt processing module generate PWM interrupt at each starting moment of the PWM triangular carriers. Through the control method of the invention, the problem of abnormal real-time instruction reception caused by non-synchronization is avoided, and a controlled servo motor is jitter-free.

The invention discloses a multi-channel electronic nose detection system and a measuring method thereof. The system consists of a gas detection chamber, a signal processing part, a wireless transmission part, an alarm module and a display module, and can monitor various gases, comprising ammonia gas, hydrogen sulfide, carbon monoxide, ethanol, formaldehyde, acetone, VOC and the like, in real time. According to the measuring method, baseline data measurement is added before gas chamber gas entering and sampling, and a time drift correction algorithm is added for gas data, so that gas data analysis is accurate. The system provided by the invention integrates gas detection, data wireless transmission and data storage, is highly integrated and intelligentized, has good auxiliary effect on industrial application, adapts to environment air monitoring of various industrial parks and air monitoring of remote regions, and has wide application prospect.

The invention discloses an eddy current displacement sensor for a high temperature magnetic bearing in an axial direction, which belongs to the field of eddy current displacement sensors. The sensor is mainly composed of four parts of a working probe, an auxiliary probe, a signal processing circuit and a temperature compensation circuit, wherein the main probe and the auxiliary probe are mainly composed of a high temperature enameled wire, a ceramic coil skeleton, a high temperature adhesive and a high temperature coaxial cable; the signal processing circuit is mainly composed of an oscillating circuit, a detection circuit and a calibration circuit; the temperature compensation circuit is mainly composed of a temperature drift compensation circuit and a time drift compensation circuit, thetemperature drift compensation circuit is mainly composed of a Pt100 three-wire system temperature acquisition circuit, a signal conditioning circuit and a divider; and the time drift compensation circuit is mainly composed of a Pt100 three-wire system temperature acquisition circuit and two probe differential circuits. Uncompensated signals firstly pass through a subtractor to eliminate bias voltage temperature drift errors of temperature drift and then pass through a division circuit to eliminate sensitivity temperature drift errors, and the sensor is mainly applied to the high temperaturemagnetic bearing in an axial direction.

The invention discloses an adaptive infrared non-uniformity calibration method based on motion state estimation. The method includes the steps of initializing a detector platform, acquiring motion parameters of the detector platform, pre-calibrating images acquired by a detector through a precalibration algorithm, estimating the image motion states of the current frame and the previous frame according to the motion parameters of the detector platform to obtain the designated position coordinate motion relation of images of adjacent two frames, obtaining the corresponding pixel gray scale of all scenes of the current frame in the previous frame according to the designated position coordinate motion relation of images of adjacent two frames, obtaining the average value of the current frame pixel gray scale and previous frame pixel gray scale of a same scene, calculating non-uniformity calibration parameters through output values of the detector according to a preset filtering model, and and re-calibrating the initially calibrated images according to the non-uniformity calibration parameters to obtain a final image. Time drift and temperature drift problems of a detector can be effectively solved.

The present invention discloses a method and an apparatus of the drift calibration of sensors. The method includes shifting the sensing signal and differential technology to remove the drift signal by time during a long measuring. The apparatus includes two voltage sensors and readout circuits, a signal-shifting circuit and a differential circuit, and the apparatus is used for outputting the response signal without time drifting.

The invention, which belongs to the field of the eddy-current displacement sensor, discloses a differential frequency conversion and amplitude modulation type eddy-current displacement sensor with the high temperature self-following stepped-compensation characteristic. The sensor is composed of a probe, a temperature induction stepping circuit and a signal processing circuit. The probe is mainly composed of a coil, a high-temperature adhesive and a ceramic coil skeleton. The temperature signal processing circuit mainly consists of an oscillation circuit, a detection circuit, a filter, a three-stage linear compensation circuit and a differential circuit. The temperature induction stepping circuit includes a thermistor, an FPGA and an analog switch circuit. The single-path temperature drift situation of the eddy-current displacement sensor is collected on the condition of no compensation; a fitting resistance ratio of a multi-stage temperature drift compensation circuit is designed; the FPGA carries out controlling to select temperature compensation circuits at different levels; and then differential time drift error elimination is carried out at two paths with opposite moving directions of a measured object and then a final signal is outputted. The sensor is applied to a high-temperature magnetic suspension bearing.