116 results about "Time to first fix" patented technology

A frequency management scheme for a hybrid communications/positioning device, such as a cellular/GPS or other combined device, generates a local clock signal for the communications portion of the device, using a crystal oscillator or other part. The oscillator output may be delivered to a phase locked loop to drive a high-frequency clock for the cellular or other communications portion of the hybrid device. A processor may determine frequency error between the phase locked loop and base station or other reference, to derive a digital frequency tracking message. A Doppler search or other logical control message may likewise be communicated from the processor to a GPS or other positioning receiver. The GPS receiver circuitry may consequently adjust Doppler center, window width or other parameters to enhance time to first fix or other performance. The architecture eliminates the need for a second crystal or other direct oscillator in the GPS receiver portion of the hybrid device, while still maintaining GPS performance. The architecture of the design also eliminates the need for frequency correcting elements in the crystal oscillator or other base reference oscillator or clock. The invention can furthermore be used in any system, radio, modem, transceiver, or receiver that has two or more receivers that share one reference or base oscillator or clock.

A system and method are provided for determining a position of a Global Positioning System (GPS) receiver prior to bit and frame synchronization. As such, the time-to-first-fix is substantially reduced. More specifically, pseudoranges to five GPS satellites are measured by correlating locally generated Pseudo-Random Number (PRN) codes with signals received from the GPS satellites. After correlation, the pseudorange measurements are correct with an unknown integer number of milliseconds error, which is different for each of the pseudorange measurements. Using the measurements of the pseudoranges and a mathematical model where each of the pseudorange measurements is forced to have a common channel time error, the user position and the common channel time error are determined prior to bit and frame synchronization.

A method, system and apparatus are claimed for receiving, blindly despreading, and determining geo-observables, of true civil Global Navigation Satellite Systems (GNSS) navigation signals generated by any of the set of satellite vehicles and ground beacons, amongst false echoes and malicious GNSS signals from spoofers and repeaters; for identifying malicious GNSS signals, and preventing those signals from corrupting or capturing Pointing, Navigation, and Timing tracking operations; and for geolocating malicious GNSS signals. The invention also provides time-to-first-fix over much smaller time intervals than existing GNSS methods and can operate both in the presence of signals with much wider disparity in received power than existing techniques, and in the presence of arbitrary multipath. Further embodiments employing spatial/polarization diverse receivers that remove non-GNSS jammers received by the system, as well as targeted GNSS spoofers that can otherwise emulate GNSS signals received at victim receivers, are also claimed.

The invention relates to an auxiliary satellite navigation system and a global positioning system (GPS) receiver, in particular to a high-sensitivity navigation receiver mainly used indoors as well as an indoor positioning GPS receiver and an auxiliary satellite navigation positioning system adopting high-sensitivity satellite navigation positioning technology. The system at least comprises a terminal receiver, a reference receiver, a positioning server and a communication network; all devices are combined into an integral indoor positioning system; the entire system is divided into a high-sensitivity satellite navigation receiver and a network auxiliary system. Through adopting the positioning mode in which point positioning under weak signal condition is combined with continuous positioning under strong signal condition, the method mainly solves related technical problems such as the organic combination of integral hardware implementation. The invention has the advantages that: the system and the method improve the sensitivity index of a terminal user and reduce first positioning time; moreover, the designed navigation receiver can process indoor weak satellite signal, etc.

A method and apparatus for estimating oscillator signal variation due to temperature and for providing an estimated frequency to a GPS receiver in order to assist the GPS receiver to acquire the signals quickly is disclosed. A temperature sensor is closely thermally coupled with the crystal oscillator in the GPS receiver and during GPS tracking mode, when the error in the oscillator signal is known with precision, outer bounds of TCXO frequency at given temperatures are maintained, which may correspond to rising and falling temperature conditions. During acquisition mode, an estimated frequency value is provided to the GPS receiver based on a determined average of these bounds. Optionally, an uncertainty factor associated with the frequency estimated may also be provided. The two bounds take into account the hysteresis effects of the oscillator signal drift due to temperature so that a more accurate initial frequency estimate can be provided to the GPS receiver, thus reducing its average time to first fix.

The embodiment of the invention provides a method and a device for achieving bit synchronization and frame synchronization of a text of a receiver. Aiming at a 500 bps text in a navigation digital receiver, the method mainly comprises the following steps: adding two adjacent 1 ms accumulated values in the text with a set time length in turn, and acquiring a text after the bit synchronization according to the accumulated value after the addition; and searching a trellis code frame header in the text after the bit synchronization according to the scheduled format information, and finishing the synchronization of the text for the bit synchronization to be determined according to the searched trellis code frame header. The method and the device can improve the speed of the bit synchronizationand the frame synchronization of navigation texts of 500 bps and 50 bps in the navigation digital receiver, save system resources, and improve the system reliability. Besides, the method and the device achieves the bit synchronization and the frame synchronization in an FPGA (Field Programmable Gate Array), and can generate the satellite launch time more quickly and shorten the first-time positioning time of the navigation digital receiver.

A method and system for transmitting navigation data to a satellite navigation receiver for reducing time to first fix is provided. A signal generation system generates a navigation data structure comprising a first sub-frame and a second sub-frame for accommodating selective ephemeris data, a third sub-frame for accommodating first parameters of almanac data, and a fourth sub-frame for accommodating a text message comprising second parameters of almanac data, and transmits the selective ephemeris data and the first and second parameters of almanac data to the satellite navigation receiver. The configuration of the navigation data structure enables the satellite navigation receiver to collect the navigation data in reduced time. Each satellite of a constellation simultaneously transmits distinct first parameters of the almanac data in the third sub-frame of the navigation data structure to the satellite navigation receiver, thereby allowing the satellite navigation receiver to receive collective almanac data in reduced time.

The present invention provides a system, method and computer program for a GNSS receiver that is operable to provide an ultra fast Time To First Fix (TTFF). The invention is implementable without requiring the decoding of a navigation message transmitted by GNSS satellite systems. The system of the present invention may comprise a parameter obtaining means, a clock obtaining means and a Fast TTFF engine. The parameter obtaining means may obtain satellite parameters of one or more GNSS satellites. The clock obtaining means may obtain a clock for estimating a GNSS time tag. The Fast TTFF engine may be linkable to a signal interface that is operable to provide I/Q samples from a GNSS antenna. The Fast TTFF engine may comprise a measurement generation utility, a coarse search utility and a fine search utility. The measurement generation utility may compute the Doppler frequency shift and the code phase of the one or more GNSS satellites based on the I/Q samples.

The invention discloses a Beidou receiver and a warm start method thereof. The warm start method of the Beidou receiver comprises the following steps of: obtaining the time T'r of a local receiving satellite signal; according to T'r, calculating a roughly-estimated satellite signal emission moment Tte; obtaining the coordinate of a satellite at the roughly-estimated satellite signal emission moment Tte; calculating the distance and the transmission time of the satellite to the last-time user positioning position; reconstructing a satellite signal emission moment T't with a error delta; according to the satellite signal emission moment T't, calculating the transmission time; comparing the transmission time with real satellite transmission time delta T to obtain the value of the error delta; regulating the error delta to add the error delta into the signal calculation of each satellite required by positioning; calculating a pseudorange; and carrying out a least square method to resolve a positioning result to finish the warm start. According to the warm start method of the Beidou receiver, which is disclosed by the invention, the first-time positioning time of the Beidou receiver can be improved, and a purpose of starting-up quick positioning is realized.

The invention relates to a method and system for updating a global position system (GPS) ephemeris fast and reliably. According to the method and system for updating the GPS ephemeris fast and reliably, a local GPS ephemeris server is established, and a virtual GPS ephemeris generating module is arranged inside the local GPS ephemeris server. Normally the local GPS ephemeris server acquires ephemeris data from a GPS official ephemeris server. When the local GPS ephemeris server is disconnected with the GPS official ephemeris server, the virtual GPS ephemeris generating module starts to work to generate an accurate virtual ephemeris, and GPS ephemeris data in the local GPS ephemeris server are instantly switched into internal virtual GPS ephemeris data to guarantee continuity and reliability of the GPS ephemeris data. According to the method and system for updating the GPS ephemeris fast and reliably, the time to first fix (TTFF) of a host computer of each A-GPS terminal is shorten obviously, the TTFF of a positioning system of each A-GPS terminal can be shortened to less than 20 seconds after cold start, and therefore fast and reliable positioning is achieved.

Systems and methods for generating a location of a mobile device using cell sector data are provided. A mobile device is in service connection with a base station, which has a corresponding service area. Upon entering the service area of another base station, the mobile device enters service connection with the second base station in a handoff event. The mobile device and/or the base station determines the location of each of the base stations, and estimates the approximate location of the mobile device based on the locations of the base stations. In one or more implementations, the estimated position can comprise a midpoint of a line joining the two base stations. The systems and methods can be implemented with a random location generator to improve accuracy. The approximate location of the mobile device can be inputted into a GPS-enabled device to reduce times to first fix.

A method and apparatus for collecting subframes of navigation data of satellites are disclosed. In the method of the present invention, the subframe is divided into several sub-units, each sub-units includes one or more words. When a receiver receives a subframe with a subframe ID, the respective required sub-units of the subframe are checked. A dummy sub-unit is not necessary to be considered. Valid ones of the required sub-units are collected. If not all the required sub-units of the subframe have been collected, the absent sub-units are to be collected when the next subframe with the same subframe ID is received. Some protection schemes can be applied to raise the reliability of such sub-unit collection. Especially when the signal is weak or unstable, the present invention may significantly improve the TTFF (Time To First Fix) performance of the receiver.

The invention relates to a method and an apparatus for compensating clock bias, wherein the apparatus for compensating clock bias which is applied to a Global Navigation Satellite System (GNSS) receiver comprises a clock source for providing a reference time which has a clock bias to be compensated and a processing module which is coupled to the clock source for deriving at least one clock drifting value. The clock drifting value contains a first clock drifting value corresponding to a first time point. The clock bias is calculated according to the at least one clock drifting time and at leastone time section, wherein the at least one time section is a time period between the first time point and a special time point after the first time point. The method and the apparatus provided by theinvention can derive the time information and obviously decrease the first locating time.

The invention relates to a capturing method of a satellite navigation signal in an adjustable carrier wave doppler frequency searching range. The method comprises the following steps that: an initial carrier wave doppler covering range and a corresponded carrier frequency is generated; code phase searching is completed under the carrier wave frequency to obtain a corresponded capturing result; because the covering of the initial carrier wave doppler is complete, search frequency point information of the carrier wave doppler that is frequency hopping information is written into a frequency hopping information memory to complete storage of the frequency hopping information that can be used for subsequent continuous capturing; and other unresearched satellites are switched for continuous execution. According to the invention, searching of an undetermined range of a carrier wave frequency can be completed at the expense of few hardware costs and a fast speed; satellites can be searched ina short time as much as possible; and first positioning time of a receiver is improved.

Disclosed in the invention is a full-wave band GSM base station information acquisition system. The method for implementing the system comprises the following steps: setting a starting mode of a global positioning system and obtaining first-time positioning time; setting interval time between scanning and searching; turning off a radio frequency switch to carry out full-waveband scanning; searching and obtaining base station signal information and base station information at a frequency point; newly adding or updating the base station signal information and base station information; uploading the base station signal information and base station information to a mobile detection terminal, carrying out querying and reporting to obtain and record base station positioning information of scanning each time; labeling the position of the base station at a map and drawing a distribution track and a zone of the base station; carrying out analyzing and classification on the base station information and the positioning information and storing the base station information; and analyzing the classified base station information for displaying. According to the information acquisition system provided by the invention, acquisition, analyzing, and classified displaying of base station information can be realized; and the precision is high and the real-time performance is excellent.