GPS receiver apparatus and information acquisition method thereof
AssigneeCasio Computer Co., Ltd.
InventorToshio Hanabusa
Life of this patent
Estimating the term…
Abstract
The first reception operation is started in response to an acquisition request. Power supply to a RF unit and a demodulator is stopped after synchronization with the GPS signal is established. Based on information acquired from a sub-frame in the GPS signal, a time point to start the second reception operation is determined. Elapsed time is counted using a counter clock synchronized with transmission timing of the navigation message, while a reception frequency of the satellite, a PRN code unique to the satellite, and a frequency and a phase of the PRN code are retained. When the elapsed time arrives at the time point, the power supply to the RF unit and the demodulator is restarted.
Claims6
A GPS receiver apparatus comprising:
- a reception unit comprising a radio frequency unit and a demodulator, the reception unit configured to receive a GPS signal transmitted from a GPS satellite and acquire a navigation message;
- a synchronization controller configured to control a reception frequency of the GPS signal and a frequency and a phase of a code of the GPS signal to ensure synchronization with the GPS signal, and generate a timing signal synchronized with a signal timing of the navigation message in the synchronized GPS signal;
- a calculation processor configured to calculate a current time based on time information included in the navigation message acquired by the reception unit;
- and
- a power controller configured to:
- start power supply to the reception unit, the synchronization controller, and the calculation processor in response to an acquisition request for a specific information contained in a specific sub-frame of sub-frames of the navigation message;
- stop the power supply to the reception unit while keeping the power supply to the synchronization controller and the calculation processor after the reception unit acquires the time information contained in one of the sub-frames of the navigation message;
- stop the power supply to the calculation processor while keeping the power supply to the synchronization controller after the calculation processor calculates the current time;
- and
- stop the power supply to the synchronization controller after a predetermined period has been elapsed from a time when the power supply to the calculation processor is stopped.
An information acquisition method for receiving a GPS signal transmitted from a GPS satellite and acquiring specific information included in a specific sub-frame of sub-frames of a navigation message, the method comprising:
- starting power supply to a reception unit, a synchronization controller, and a calculation processor and reception operation for the GPS signal in response to an acquisition request for the specific information;
- controlling a reception frequency of the GPS signal and a frequency and a phase of a code of the GPS signal to ensure synchronization with the GPS signal in response to start of the reception operation;
- generating a timing signal synchronized with signal timing of the navigation message in the synchronized GPS signal;
- stopping a power supply to the reception unit while keeping the power supply to the synchronization controller and the calculation processor after time information contained in one of the sub-frames of the navigation message is acquired;
- stopping the power supply to the calculation processor while keeping the power supply to the synchronization controller after the calculation processor calculates a current time;
- and
- stopping reception operation of the GPS signal by stopping the power supply to the synchronization controller after a predetermined period has elapsed after a time when the power supply to the calculation processor is stopped.
Dependencies are inferred from the claim text.