Method, apparatus and system for GPS time synchronization using cellular signal bursts
First Claim
1. A method, comprising:
- responding to a cellular communication signal received by an antenna by generating, by a cellular module, a trigger pulse derived from a data component of the cellular communication signal;
providing the trigger pulse to a trigger register via a special hardware path that is configured to provide the trigger pulse without substantial random delay, wherein the special hardware path is a path between the cellular module and a global positioning system module that are located in a global positioning system receiver;
accessing, by the global positioning system module, a signal indicating local time; and
responding to the trigger pulse provided via the special hardware path and responding to the signal indicating local time, by providing a local time value for receipt of the trigger pulse.
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Accused Products
Abstract
A system, apparatus and corresponding method by which to synchronize to a time reference a main module of a device—a main module such as global positioning system (GPS) receiver—using a cellular communication signal received by a cellular module also included in the device. To synchronize the main module to the reference time, the invention provides a method including the steps of: having the cellular module respond to the cellular communication signal by providing to a clock module of the main module a trigger pulse derived from the data component of the cellular communication signal, and also by providing to the main module information relating the trigger pulse to a universal time. The main module is then able to resolve a value for time based on the information relating the trigger pulse to a universal time and the trigger pulse.
51 Citations
10 Claims
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1. A method, comprising:
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responding to a cellular communication signal received by an antenna by generating, by a cellular module, a trigger pulse derived from a data component of the cellular communication signal; providing the trigger pulse to a trigger register via a special hardware path that is configured to provide the trigger pulse without substantial random delay, wherein the special hardware path is a path between the cellular module and a global positioning system module that are located in a global positioning system receiver; accessing, by the global positioning system module, a signal indicating local time; and responding to the trigger pulse provided via the special hardware path and responding to the signal indicating local time, by providing a local time value for receipt of the trigger pulse. - View Dependent Claims (2, 8, 9)
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3. An apparatus, comprising:
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means, responsive to a cellular communication signal received by an antenna, for generating, by a cellular module, a trigger pulse derived from a data component of the cellular communication signal; means for communicating the trigger pulse to a trigger register via a special hardware path that provides the trigger pulse without substantial random delay, wherein the special hardware path is a path between the cellular module and a global positioning system module that are located in a global positioning system receiver; and means, responsive to the trigger pulse and to a signal indicating local time, for providing a local time indicative of when the trigger pulse is received.
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4. An apparatus, comprising:
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a cellular module, responsive to a cellular communication signal received by an antenna, for generating a trigger pulse derived from a data component of the cellular communication signal; a special hardware path, configured for communicating the trigger pulse to a trigger register without substantial delay, wherein the special hardware path is a path between the cellular module and a global positioning system module that are located in a global positioning system receiver; and the trigger register, responsive to the trigger pulse and to a signal indicating local time, for providing a local time indicative of when the trigger pulse is received. - View Dependent Claims (5, 6, 7)
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10. A method, comprising:
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receiving a time-stamped frame containing a time-stamp from a location measurement unit; determining, by a cellular module, a time-mark value for a frame yet-to-be received, wherein the time-mark value is based on the time-stamp but includes a correction due to propagation delay of the time-stamp between a serving cellular base station and a global positioning system receiver; triggering a global positioning system module of the global positioning system receiver via a special hardware path between the global positioning system module and the cellular module of the global positioning system receiver; providing to the global positioning system module via a software connectivity layer a frame number and the time-mark; receiving, by the global positioning system module, a trigger signal via the special hardware path; recording in a register of the global positioning system module a time at which the trigger signal was received, according to a local clock; receiving a time-mark message over the software connectivity layer; recording a time at which the time-mark message is received, according to the local clock; determining, by the global positioning system module, a difference in time between the time when the trigger was received and the time when the time-mark message was received; adding the determined time difference to the time-mark message to determine true global positioning system time; and setting the local clock to true global positioning system time.
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Specification