Trimble Navigation Limited

Yiming Jim Yu

Peter Van Wyck Loomis

Xiaorong Zhi

Joseph W Fontes

Michael Paul Dentinger

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.

GNSS time fraction calibration of a real time clock

A GPS receiver and method using alternating 'A' and 'B' integration time segments. The polarities of certain GPS data bits are known beforehand and their expected reception times are known. The GPS signal in 10 millisecond &#x201c;A&#x201d; time segments and &#x201c;B&#x201d; time segments is depolarized according to the known polarities. The depolarized GPS signal during an &#x201c;A&#x201d; time period made up of all the &#x201c;A&#x201d; time segments is integrated for providing an &#x201c;A&#x201d; time period magnitude for each code phase. Likewise, the depolarized GPS signal during a &#x201c;B&#x201d; time period made up of all the &#x201c;B&#x201d; time segments is integrated for providing a &#x201c;B&#x201d; time period magnitude for each potential GPS code phase. The strongest of the time period magnitudes is compared to a correlation threshold for selecting a code phase for signal acquisition.

Signal receiver using alternating time segments

Fast time to first fix by calibration of a real time clock

A GPS receiver for integrating a GPS signal separately in a series of 'A' type and 'B' type time segments, the &#x201c;A&#x201d; segments alternating with the &#x201c;B&#x201d; time segments; combining the squares of the magnitudes of &#x201c;A&#x201d; time segment integrations corresponding to code phases for forming &#x201c;A&#x201d; type combined magnitudes; combining the squares of the magnitudes of the &#x201c;B&#x201d; time segment integrations corresponding to code phases for forming &#x201c;B&#x201d; type combined magnitudes; and determining an acquisition code phase of the signal from the strongest of the &#x201c;A&#x201d; or &#x201c;B&#x201d; combined magnitudes. The &#x201c;A&#x201d; time segments and the &#x201c;B&#x201d; time segments are one-half the period of the data bits of the signal, thereby ensuring that either the &#x201c;A&#x201d; time segments or the &#x201c;B&#x201d; time segments avoid the nullifying effect of data bit inversions.

Signal receiver for integrating and combining integrations in alternating time segments for signal acquisition at low signal strength

A GPS receiver having a fast method for determining GPS clock time. The GPS receiver includes a signal processor for receiving GPS signals from GPS satellites and detecting current GPS data bits carried by the respective GPS signals, a chapter memory for storing a block of expected GPS data bits for the respective GPS satellites, and a GPS time detector for detecting a successful match when a chunk of the expected data bits within a selected search range within the block matches a chunk of the current data bits, and using the successful match for determining the GPS clock time. In an anytime embodiment the GPS receiver enters an operation mode at any time in order to minimize user request latency. In a focused embodiment the GPS receiver enters the operation mode at a prescribed time-of-entry in order to minimize power consumption for cycles of standby and operation modes.

GNSS receiver using stored navigation data bits

GPS receiver having a prescribed time-of-entry into an operation mode

GPS receiver using stored navigation data bits for a fast determination of GPS clock time

Signal receiver having signal acquisition at low signal strength using interleaved time segments

Signal receiver using coherent integration in interleaved time periods for signal acquisition at low signal strength

An indoor GPS clock using GPS signals lower that &#x2212;143 dBm for issuing disciplined frequency and time standard signals. The indoor GPS clock includes a correlation machine using long integration periods for enabling the indoor GPS clock to operate with low signal levels; a carrier-less tracking loop for tracking the low level signals without carrier offset feedback, a clock bias loop for providing clock bias feedback; and a reference oscillator using the clock bias feedback for providing disciplined frequency and time signals having greater accuracy than is available in conventional GPS positioning receivers. The indoor GPS clock also includes a holdover driver providing compensation for predicted drift in clock bias error for disciplining the reference oscillator for several hours when the GPS signal is no longer being received.

Indoor GPS clock

An indoor GPS clock using GPS signals lower that &minus;143 dBm for issuing disciplined frequency and time standard signals. The indoor GPS clock includes a correlation machine using long integration periods for enabling the indoor GPS clock to operate with low signal levels; a carrier-less tracking loop for tracking the low level signals without carrier offset feedback, a clock bias loop for providing clock bias feedback; and a reference oscillator using the clock bias feedback for providing disciplined frequency and time signals having greater accuracy than is available in conventional GPS positioning receivers. The indoor GPS clock also includes a holdover driver providing compensation for predicted drift in clock bias error for disciplining the reference oscillator for several hours when the GPS signal is no longer being received.

The position, velocity, time (PVT) and attitude (ATT) measurement system including a Master GPS antenna and a plurality of Slave GPS antennas is disclosed. The system comprises a hardware PVT channel and a hardware ATT channel. After the Master GPS antenna is selected, the hardware PVT channel stays locked on the Master antenna during the measurement time thus optimizing the accuracy of the PVT data. The PVT channel performs the tracking of the visible GPS satellites and generates the tracking data and the PVT data. The ATT channel performs the attitude measurement using all Slave antennas and the PVT tracking data.

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Cupertino, CA, United States of America

Yiming Jim Yu