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US 8,805,376 B2Granted
Satellite (GPS) assisted clock apparatus, circuits, systems and processes for cellular terminals on asynchronous networks
AssigneeTexas Instruments Incorporated
InventorsJoergen Boejer, Alain Vallauri, Ilyas Berk Guvelioglu
Life of this patent
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Abstract
An electronic circuit for use with time of arrival signals from a network, including a position determination unit, a first clock, a second clock, and processing circuitry coupled to said first clock, said second clock, and said position determination unit. The processing circuitry is operable to project a relatively-accurate subsequent global time based on said first and second clocks and to then return said relatively-accurate subsequent global time to said position determination unit to facilitate a subsequent position determination by said position determination unit.
Claims20
An electronic circuit for use with time of arrival signals from a network, the electronic circuit comprising:
- a position determination unit operable to generate a global time value and to convey a first global time from said position determination unit as an output;
- a first clock greater than 1 MHz, said first clock operable to be powered on and off;
- a second clock less than 1 MHz having cycles;
- and
- processing circuitry coupled to said first clock and to said second clock and to said position determination unit, said processing circuitry operable to:
- measure a time interval between the time of arrival signals relative to first clock counts and measure a time interval between cycles of said second clock relative to first clock counts;
- generate a number n2 of clock counts of said first clock when said first clock is powered on and generate a number of clock counts n3 of said second clock while said first clock is powered off;
- and
- project a relatively-accurate subsequent global time based on said first global time and using said measure and generate operations;
- and
- then return said relatively-accurate subsequent global time to said position determination unit to facilitate a subsequent position determination by said position determination unit;
- and
- wherein said processing circuitry is operable to project the relatively-accurate subsequent global time as a sum of products and ratios of time intervals and counter values representing numbers n of clock beats according to a relation
- tCT=t0+[n1+(n2/RCP0)+n3(XRTC/RCP0)]Tcellular
- where
- t0 is the first global time value,
- tCT is the relatively-accurate subsequent global time from time projection,
- Tcellular is the time interval between the time of arrival signals,
- RCPO is number of first clock counts in the time interval Tcellular,
- XRTC is number of first clock counts between cycles of said second clock,
- n1 is a number of received instances of the time interval Tcellular,
- n2 is the number of first clock counts distinct from periods counted with n1, and
- n3 is the number of second clock periods distinct from periods counted with n1 and n2.
20 more elements
An electronic circuit for use with time of arrival signals from a network, the electronic circuit comprising:
- a position determination unit operable to generate a global time value and to convey a first global time from said position determination unit as an output;
- a first clock greater than 1 MHz, said first clock operable to be powered on and off;
- a second clock less than 1 MHz having cycles;
- and
- processing circuitry coupled to said first clock and to said second clock and to said position determination unit, said processing circuitry operable to:
- measure a time interval between the time of arrival signals relative to first clock counts and measure a time interval between cycles of said second clock relative to first clock counts;
- generate a number n2 of clock counts of said first clock when said first clock is powered on and generate a number of clock counts n3 of said second clock while said first clock is powered off;
- and
- project a relatively-accurate subsequent global time based on said first global time and using said measure and generate operations;
- and
- then return said relatively-accurate subsequent global time to said position determination unit to facilitate a subsequent position determination by said position determination unit;
- and
- wherein said signals have frames and intra-frame intervals that span plural periods of the first clock, and said processing circuitry is operable to project the relatively-accurate subsequent global time by also keeping a separate count n4 of an intra-frame number IFN of the intra-frame intervals and according to a relation
- tCT=t0+(n1−1)×Tcellular+n4×Tifn+n2×Ton—clock+n3×Tsleep—Clock
- where
- t0 is the first global time value,
- tCT is the relatively-accurate subsequent global time from time projection,
- Tcellular is the time interval between the time of arrival signals,
- Ton—clock is the time period of the first clock,
- Tsleep—Clock is the time period of the second clock,
- Tifn is the time interval of each intra-frame interval,
- n1−1 is a number of receiver synchronization instances (RSIs) spaced by Tcellular,
- n2 is the number of first clock counts distinct from periods counted with n1, and
- n3 is the number of second clock periods distinct from periods counted with n1 and n2.
21 more elements
Dependencies are inferred from the claim text.