Magellan Systems Japan, Inc.

Other

Nobuhiro Kishimoto

Seiichiro Hirata

Sergey Lyusin

Toshinobu Nagamatsu

Takehiro Ohnishi

Authentication mechanism is provided to open service signals in Global Navigation Satellite Systems (GNSS), by inverting a plurality of bits in a pseudorandom noise code in a GNSS signal having a predetermined period of a binary bit sequence of N bits. A position of each inverted bit in the binary bit sequence is specified by a serial number generated for each period using a cryptographic pseudorandom number generator, where at least one of the position of the inverted bit and a number of the inverted bits in the period varies period by period. A decryption key is provided to a GNSS receiver, which correlates, using a corresponding cryptographic pseudorandom number generator, the received GNSS signal, and accumulates an amplitude thereof at the inverted bit, thereby determining if the received signal is counterfeit based on the ratio of the inverted bit amplitude with respect to the signal amplitude.

Method and system for providing authentication to GNSS open service signals and interoperable secure positioning

An apparatus provides independent precise positioning for a reference station including a GNSS antenna and a GNSS receiver. The GNSS receiver generates GNSS data based on a plurality of GNSS signals received at the GNSS antenna, including GNSS signals having augmentation information. The apparatus includes a positioning processor, a signal processor, and a signal transmitter. The positioning processor calculates a current position of the reference station based on GNSS observation data and GNSS augmentation data obtained from the augmentation information included in the received GNSS signals, without using position information of another reference station, whereby the reference station is independently installed at a desirable location without surveying or measuring the desirable location. The signal processor generates error correction information including the current position of the reference station in a predetermined data format such as RTCM or CMR, based on the GNSS augmentation data.

High precision independent positioning apparatus for reference station

A reference station includes a GNSS antenna configured to receive a plurality of GNSS signals including augmentation information, and a GNSS receiver having a positioning processor, a signal processor, and a signal transmitter. The positioning processor calculates a current position of the reference station based on received GNSS signals including the augmentation information without using position information of another reference station or error correction information sent via a non-GNSS satellite communication link, and thus the reference station can be independently installed at a desirable location without surveying or measuring the desirable location. The signal processor generates error correction information including the current position of the reference station in a predetermined data format such as RTCM or CMR, based on the received GNSS signals. The signal transmitter transmits the error correction information via a communication link, allowing rovers to perform centimeter-level RTK positioning using the current position of the reference station.

Reference station with high precision independent positioning function

In RTK positioning, a calibration memory stores calibration information for combinations of GNSS receivers. A memory processor retrieves the calibration information for a selected combination of a first GNSS receiver for a base station and a second GNSS receiver for a rover from the calibration memory. A calibration apparatus, by communicating with the rover and the memory processor, receives a first correction signal associated with the first GNSS receiver, obtains the calibration information and modifies the first correction signal therewith to generate a modified correction signal calibrated for the second GNSS receiver with respect to the first GNSS receiver, and transmits the modified correction signal to the rover. The rover performs the RTK positioning with respect to a known GNSS receiver of the base station using the modified correction signal, thereby automatically achieving the frequency-dependent hardware bias calibration for the second GNSS receiver with respect to the first GNSS receiver.

System and method for calibrating inter-frequency hardware bias in RTK positioning using error correction information

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. The delay value is used to obtain a pseudorange measurement and the measured Doppler shift permits further correction to the local oscillator frequency, thus reducing the frequency search range for the remaining satellites.

Method and system for GPS position measuring and frequency error detecting method

A GPS positioning method to obtain pseudorange between a receiver terminal and a satellite by capturing a portion of received satellite signals of a predetermined time duration. A predetermined number of first input signals, equivalent to 1-bit of navigation data, are obtained with various delays in the starting point of processing. The first input signals are synchronously summed up to obtain second input signals. A PN code replica (pseudopattern) prepared by the receiver terminal operates on the second input signals to detect the polarity of the navigation bits and correct the polarity of the bits so that the bit polarity of the second input signals are always positive. Synchronous summation is conducted on the resulting signals, which have been derived from the complete captured signal, and a correlation calculation is conducted on the obtained synchronously summed signal using a replica PN code prepared by the receiver terminal, the signal delay value is detected and pseudorange is obtained using the result of the correlation calculation.

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Osaka, Japan

Nobuhiro Kishimoto