US 2003/0119503 A1 · Communication device with a self-calibrating sleep timer

Abstract

The present invention provides for a system for operating a communication device (20) for reception of scheduled intermittent information messages (22) with a dual mode timer (70) that extends battery life. A controller (50) schedules the timer (70) to power down all idle components of the device (20) between message receptions in a power saving sleep mode to conserve battery power. During active mode when the device is fully active in reception of messages, the timer (70) uses a reference oscillator (90) with a relatively high frequency to support digital processing by the receiver (26). During sleep mode when only the timer is powered on, a much lower frequency sleep oscillator (96) is used to maintain the lowest possible level of power consumption within the timer itself. The timer (70) has provision for automatic temperature calibration to compensate for timing inaccuracies inherent to the low-power low-frequency crystal oscillator (96) used for the sleep mode. The resultant improvement in timer accuracy during sleep mode eliminates the need for an initial reacquisition period following wake up in active mode, thereby reducing battery drain in active mode as well.

Claims30

Dependent claims

A system for operation of a communication device adapted to be operated by a battery for reception of scheduled intermittent information messages (22) comprising a receiver (26) for receiving the messages, a dual mode timer (70), for continually maintaining time and operable in two modes, an active mode and a power saving sleep mode, a controller (50) for scheduling the timer (70) to power down idle components of the receiver (26) between message receptions in the power saving sleep mode to conserve battery power, a reference oscillator (90) for controlling the timer (70) operative during the active mode when the device is fully active in reception of messages, said reference oscillator (90) operating with a relatively high frequency to support digital processing by the receiver (26), and a sleep oscillator (96) operative during the sleep mode when only the timer (70) is powered ON, said sleep oscillator (96) operative at a much lower frequency than the reference oscillator (90) for maintaining the lowest possible level of power consumption within the timer (70).

A system for operating a battery operated communication device with reduced power consumption wherein the communication device is adapted to receive radio signals containing intermittently scheduled digital messages, the communication device comprising

receiver means for frequency downconversion of said radio signals and demodulation of said digital messages;
a dual mode timer for continually maintaining system time while operating in one of two modes, said modes comprising an active mode and a sleep mode;
controller data processing means for data processing of the demodulated message data to extract the messages;
a reference oscillator for generating a reference clock, wherein the frequency of said reference clock is high enough to serve as clocking requirements for digital processing in the receiver and controller during the active mode, and wherein the frequency of said reference clock is responsive to input of an automatic frequency control word to the reference oscillator;
a sleep oscillator for generating a frequency which is low relative to the frequency of the reference clock and wherein power consumption of the sleep oscillator is very low relative to the power consumption of the reference oscillator;
controller means for supervising operation of the communication device, wherein said supervision is executed by a microprocessor operation with program memory contained in a storage register.

3 more elements

Dependencies are inferred from the claim text.

Communication device with a self-calibrating sleep timer

Life of this patent

Communication device with a self-calibrating sleep timer

Life of this patent

Abstract

Claims30