Abstract: A receiver terminal receives a frequency from an external reference oscillator portion, which is more accurate than that of a frequency generated within the receiver in a local oscillator portion. The frequency from the local oscillator portion is measured using the external frequency as the reference, which determines the error in the local oscillator frequency relative to the external reference and permits the local oscillator frequency to be corrected to within the error of the external oscillator frequency. A plurality of candidate values for the remaining local frequency error are selected within a predetermined frequency range to include any remaining error of the local oscillator frequency. The received signal from a satellite is correlated with a matching pseudorandom code to detect the signal and measure the signal delay and Doppler shift of the signal relative to the corrected local oscillator frequency.

Abstract: A method of and system for calibrating un-calibrated time information within a mobile terminal 101 is disclosed. The terminal has a receiver 203 capable of receiving signals from which calibrated time information carried by a calibrated system (a satellite positioning system) can be extracted, and a receiver 200 capable of receiving signals from which un-calibrated time information carried by an un-calibrated stable system (a cellular communications system) may be extracted. The time offset between calibrated time information extracted from the calibrated system and un-calibrated time information extracted from the un-calibrated stable system is determined at a first terminal position where the signals from the un-calibrated stable system are available, the travel times of the signals from the un-calibrated stable system are known or determined, and the signals from the calibrated system are available.

Abstract: An electronic device for decoding a navigation data by using a phase angle variation and a method thereof are described, which includes the following steps. A phase angle difference between the first phase angle of the first navigation data and the second phase angle of the second navigation data from a satellite signal is calculated. When the phase angle difference is greater than 90 degrees, the first navigation data and the second navigation data are determined to have opposite signs. The second navigation data according to the first navigation data and the result is determined. Therefore, each data is interpreted through directly comparing whether the phase angle difference with the previous data is greater than 90 degrees or not, so that the correct rate in decoding the navigation data is increased.

Abstract: A global navigation satellite system (GNSS) enabled mobile device comprising a crystal oscillator and an automatic frequency correction (AFC) circuit may be operable to share the crystal oscillator between processing of cellular radio signals and processing of GNSS data messages. The GNSS enabled mobile device may be operable to enforce an AFC correction when the crystal oscillator drifts beyond a specific frequency error. The AFC correction may be allowed during time intervals corresponding to GNSS words at which decoding of these words is not required. The GNSS enabled mobile device may be operable to disable the AFC correction during time intervals associated with decoding of words while the crystal oscillator may drift within the specific frequency error range. After the decoding of one or more of words is completed, the AFC correction may be allowed during the time intervals corresponding to these words.

Abstract: A method for obtaining GNSS time in a GNSS receiver includes: deriving a relationship between a first clock signal and the received GNSS time; latching a second clock signal and the first clock signal at a first latching point to obtain a clock value A1 of the first clock signal and a clock value B1 of the second clock signal; calculating a GNSS time C1 corresponding to the clock value A1 according to the relationship; latching the first clock signal and the second clock signal at a second latching point to obtain a clock value A2 of the first clock signal and a clock value B2 of the second clock signal; and calculating a GNSS time C2 corresponding to the clock value A2 according to the GNSS time C1, the clock value B1, and the clock value B2.

Abstract: 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.

Abstract: A method for obtaining GNSS time in a GNSS receiver includes: obtaining a time relationship between a first clock signal and the received GNSS time; obtaining a clock value B1 of a second clock signal and further obtaining an associated clock value A1 of the first clock signal to obtain a first pulse relationship at a first time point; calculating a GNSS time C1 corresponding to the clock value A1 according to the time relationship; obtaining a clock value B2 of the second clock signal and further obtaining an associated clock value A2 of the first clock signal to obtain a second pulse relationship at a second time point; and calculating a GNSS time C2 according to the GNSS time C1, the clock value B1, and the clock value B2. Exemplary values of A1, B1, C1, A2 B2, and C2 can be TTick1, FN1, TOW1, TTick2, FN2, and TOW2, respectively.

Abstract: A satellite signal reception device has a reception unit that receives a satellite signal transmitted from a positioning information satellite, and a reception control component that controls the reception unit to execute a reception process.

Abstract: A method for obtaining a precise intermediate frequency for a global positioning system (GPS) is applied in a GPS receiver having a radio frequency (RF) module. Using a satellite signal received by the RF module, ephemeris data of a satellite is completely obtained, and present coordinate of the GPS receiver is calculated. First coordinate of the satellite at first time point and second coordinate of the satellite at second time point are calculated using the ephemeris data. Then, traveling speed of the satellite and projection value of the traveling speed on position vector from the first coordinate to the present coordinate are calculated using the first time point, the first coordinate, the second time point, and the second coordinate. Finally, the precise intermediate frequency is calculated using the signal frequency, a carrier frequency of the satellite, the projection value, and velocity of light.

Abstract: A spoofer location system includes a number of receivers that receive positioning signals. A data engine receives information from the receivers and determines a location of a spoofer source signal. The location of the spoofer source signal is determined by determining a range from each of the number of receivers to the source. The system can be employed in a global positioning system. The spoofer location system can be utilized with guided munitions and other vehicles.

Abstract: A system and method of providing a clock signal to a navigation satellite receiver in a device is disclosed. A clock signal generated by a voltage controlled temperature compensated crystal oscillator (VCTCXO) in a cellular engine of the same device is appropriated to clock a numerically controlled oscillator (NCO) programmed to generate an adjusted clock signal suitable for use in receiving signals from navigation satellites and to heterodyne them down to baseband or an intermediate frequency for processing. Preferably, if the cellular engine has an automatic frequency control (AFC) module for adjusting the voltage control input to the VCTCXO to compensate for a change in the operating environment of the cellular engine, the AFC module modifies the control word in the NCO to counteract such adjustment so that the adjusted clock signal provided to the navigation satellite receiver is not unduly impacted.

Abstract: A GNSS enabled mobile device is operable to receive two or more system clocks via from a plurality of associated non-GNSS communication networks, for example, GSM, GPRS, UMTS, EDGE, EGPRS, LTE, WiMAX, high-speed wireless LAN (WiFi), and/or short-range wireless (Bluetooth). The received system clocks are used to calibrate an local GNSS clock for the GNSS enabled mobile device. The GNSS enabled mobile device communicates the received system clocks with an associated GNSS receiver without using an external circuitry. The GNSS receiver selects a calibration clock from the received system clocks based on the status (active or inactive) of corresponding system clocks. An active system clock is selected as the calibration clock. The associated local GNSS clock is calibrated by removing clock errors from the associated local GNSS clock using the selected calibration clock. The calibrated local GNSS clock is used for detecting GNSS signals and/or processing detected GNSS signals.

Abstract: A GPS receiver outputs pseudo distances each containing a clock bias error. A clock bias and a reception position are calculated based on each of the outputted pseudo distances. A clock drift is calculated based on clock biases at past n points or Doppler information outputted from the GPS receiver. Based on the calculated clock drift, a reference clock bias is estimated using a regression equation or a Kalman filter. Thereby, a position-fix accuracy is evaluated appropriately, without needing external data, such as autonomous navigation information.

Abstract: Various techniques are provided for calibrating a frequency of a local clock using a satellite signal. In one example, a method of transferring frequency stability from a satellite to a device includes receiving a signal from the satellite. The method also includes determining a code phase from the satellite signal. The method further includes receiving aiding information. In addition, the method includes calibrating a frequency of a local clock of the device using the code phase and the aiding information to substantially synchronize the local clock frequency with a satellite clock frequency.

Abstract: Aspects of a method and system for calibrating group delay errors in a combined GPS and GLONASS receiver are provided. The combined GPS and GLONASS receiver may be enabled to receive both GPS signals and GLONASS signals. GPS based navigation information may be calculated based on the received GPS signals. Group delay errors resulted by the received GLONASS signals may be calibrated based on the GPS based navigation information. Respective GLONASS signals may be estimated in responsive to the GPS based navigation information. Corresponding clock information associated with the estimated GLONASS signals may be transferred from the clock information of the GPS based navigation information. A calibration signal may be generated by comparing the estimated GLONASS signals with the received GLONASS signals. The calibration signal may be processed by an error state Kalman filter and may be used to offset the group delay errors in the combined GPS and GLONASS receiver.

Abstract: A handheld electronic device, such as a GPS-enabled wireless communications device with an embedded camera, a GPS-enabled camera-phone or a GPS-enabled digital camera, determines whether ephemeris data needs to be obtained for geotagging digital photos taken with the device. By monitoring user activity with respect to the camera, such as activation of the camera, the device can begin pre-acquisition of a GPS position fix by obtaining needed ephemeris data before the photograph is actually taken. This GPS pre-acquisition improves the likelihood that a position fix (GPS lock) is achieved by the time the photo is taken (to enable immediate geotagging). Alternatively, the photo can be geotagged retroactively by appending the current location to the metadata tag associated with the digital photo. An optional acquisition status indicator can be displayed on a user interface of the device to indicate that a position fix is being obtained.

Abstract: A method (200) and apparatus (100) for calibrating a global positioning system oscillator is disclosed. The apparatus may include a global positioning system receiver (120), a temperature compensated oscillator (130) coupled to the global positioning system receiver, a controller (140) coupled to the global positioning system receiver, and an offset module (150) coupled to the controller. The controller can control the operations of the apparatus. The offset module can send a calibration signal to the global positioning system receiver using values corresponding to an oscillator frequency rate of change vs. time.