GPS baseband controller architecture
View Patent ↗A GPS receiver includes an RF front end for acquiring and tracking a satellite signal and a baseband processor configured to preserve power. The baseband processor includes a GPS engine configured to process the satellite signal and generate a PVT fix, a power supervisory module for receiving the PVT fix, and a user state module that determines an environmental state, wherein the power supervisory module may power down the GPS receiver for a period of time based on a result of the determined environment state. The baseband processor also includes a time-based management module that adjusts the TCXO in response to the determined environmental state. The GPS receiver includes a plurality of operation modes, each of which is associated with a plurality of tracking profiles.
1. A method of reducing power consumption in a GPS receiver comprising a gauging circuit including a first counter running on a clock of a real time clock and a second counter running on a clock of a local oscillator having a clock frequency higher than a clock frequency of the real time clock, the method comprising:
acquiring and tracking a GPS signal, by the GPS receiver, from a number of satellites to obtain a PVT fix;
determining an environmental state by the GPS receiver;
assigning an accuracy index characterized by a number of received GPS signals, by the GPS receiver, to the obtained PVT fix;
selecting, by the GPS receiver, a tracking profile from a plurality of tracking profiles in accordance with the determined environmental state and in response to a feedback signal in order to maintain the accuracy index within a predefined range, wherein the tracking profile is associated with a tracking operation mode configured to provide the PVT fix to a host at a regular time or space interval within the predefined range of the target accuracy;
operating the gauging circuit of the GPS receiver;
simultaneously stopping the first and second counters when the first counter reaches a predetermined count; and
calibrating the real time clock based on a number of clock cycles counted in the second counter,
wherein, at power up, the GPS receiver enters in a hibernate mode where the GPS receiver is powered down except a backup memory and a system memory when the GPS receiver does not receive a command from the host within a predetermined time period, the method further comprising:
waking up the GPS receiver from the hibernate mode by sending a wake-up signal to the GPS receiver by the host.
2. The method of claim 1 , wherein the accuracy index is characterized by the strength of the received GPS signals.
3. The method of claim 1 , wherein the accuracy index is associated with a position accuracy range, or a velocity accuracy range or a combination of position accuracy range and velocity accuracy range.
4. The method of claim 1 further comprising:
storing the PVT fix in a memory.
5. The method of claim 1 further comprising:
estimating a sleep time interval until a beginning of a new tracking window for obtaining a next PVT fix.
6. The method of claim 1 further comprising:
operating the GPS receiver in a one-shot PVT fix mode.
7. The method of claim 1 , wherein the regular time or space interval is programmable by the host.
8. The method of claim 1 , wherein the plurality of tracking profiles comprises a continuous tracking profile, a low power intermittent tracking profile, a background intermittent tracking profile, and a high-accuracy intermittent tracking profile.
9. The method of claim 8 , wherein the background intermittent tracking profile is associated with a deep sleep mode, in which the GPS receiver is powered down with an exception of the backup memory or the system memory, and the real time clock.
10. The method of claim 9 , further comprising:
resuming the tracking of the GPS signal upon waking up from the deep sleep mode using the calibrated real time clock.
11. The method of claim 1 , wherein a time period for powering-down the GPS receiver is adjustable based on a host triggered event.
12. The method of claim 1 , wherein a time period for powering-down the GPS receiver is adjustable based on the determined environmental state.