Method and apparatus for adjusting reference oscillator frequency in a mobile wireless device
First Claim
1. Within a mobile device comprising cell phone circuitry and GPS circuitry, a method for producing a reference signal for a GPS receiver comprising:
- producing a cellular oscillator signal and a frequency error signal within the cell phone circuitry, where the frequency error signal is for controlling an oscillator to operate the cell phone circuitry within cell phone network specifications;
coupling the oscillator signal to at least one numerically controlled oscillator within GPS circuitry;
processing the frequency error signal to produce a frequency control value that is coupled to the at least one numerically controlled oscillator;
generating, within the at least one numerically controlled oscillator, a signal in response to the cellular oscillator signal and the frequency control value that is used for processing GPS satellite signals;
searching for a pilot tone or a carrier signal of a cellular telephone by tuning a frequency of an oscillatory signal generator;
fixing the frequency of the oscillatory signal generator when the pilot tone or the carrier signal are not found;
searching for the GPS satellite signals; and
returning to searching for a pilot tone or a carrier signal when the GPS satellite signals are not found.
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Accused Products
Abstract
A method and apparatus for using a conventional oscillator in a cellular telephone transceiver as a source of a reference signal for a GPS receiver. In one embodiment, the method comprises using a voltage-controlled oscillator (“VCXO”) within a cellular telephone transceiver to generate a reference frequency signal for the GPS receiver. Circuitry within the telephone transceiver generates a frequency error signal. Both of these signals are coupled to GPS circuitry and used to control a carrier numerically controlled oscillator (“NCO”) and a code NCO. The NCOs produce a tuning signal and a timing signal, respectively. The GPS circuitry uses the NCO generated signals to process GPS signals.
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Citations
19 Claims
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1. Within a mobile device comprising cell phone circuitry and GPS circuitry, a method for producing a reference signal for a GPS receiver comprising:
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producing a cellular oscillator signal and a frequency error signal within the cell phone circuitry, where the frequency error signal is for controlling an oscillator to operate the cell phone circuitry within cell phone network specifications; coupling the oscillator signal to at least one numerically controlled oscillator within GPS circuitry; processing the frequency error signal to produce a frequency control value that is coupled to the at least one numerically controlled oscillator; generating, within the at least one numerically controlled oscillator, a signal in response to the cellular oscillator signal and the frequency control value that is used for processing GPS satellite signals; searching for a pilot tone or a carrier signal of a cellular telephone by tuning a frequency of an oscillatory signal generator; fixing the frequency of the oscillatory signal generator when the pilot tone or the carrier signal are not found; searching for the GPS satellite signals; and returning to searching for a pilot tone or a carrier signal when the GPS satellite signals are not found. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19)
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Specification