Communication device with a self-calibrating sleep timer
First Claim
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1. 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 comprisingreceiver 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; and
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, the controller means including;
controller scheduling means for scheduling commands for supervision of the communication device, event scheduler means for receiving scheduling commands, the event scheduler means including registers for records of scheduled events, each scheduled event comprising a command word that initiates a processing event and the scheduled system time for execution of said command, the event scheduler continually monitoring system time for a match with the scheduled time in any of the records, said match causing execution of the command in the record for which the match occurs; and
controller frequency tracking means for providing for automatic frequency control wherein received downconverted signals are processed to generate a frequency control word for the reference oscillator at the rate of once per message reception such that the frequency of the reference oscillator clock is frequency-locked to the received signal.
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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.
83 Citations
14 Claims
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1. 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; and
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, the controller means including;
controller scheduling means for scheduling commands for supervision of the communication device, event scheduler means for receiving scheduling commands, the event scheduler means including registers for records of scheduled events, each scheduled event comprising a command word that initiates a processing event and the scheduled system time for execution of said command, the event scheduler continually monitoring system time for a match with the scheduled time in any of the records, said match causing execution of the command in the record for which the match occurs; and
controller frequency tracking means for providing for automatic frequency control wherein received downconverted signals are processed to generate a frequency control word for the reference oscillator at the rate of once per message reception such that the frequency of the reference oscillator clock is frequency-locked to the received signal. - View Dependent Claims (2, 3, 4, 5, 6, 7)
determine a plurality of sleep mode timer calibration settings, each respective to a corresponding temperature;
store the plurality of sleep mode timer calibration settings;
when the measured temperature compares favorably to a stored temperature, retrieve a corresponding sleep mode timer calibration setting; and
apply the retrieved sleep mode timer calibration setting to the dual mode timer.
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8. A battery operated communication device comprising
a receiver that receives, down converts, and demodulates radio signals to produce demodulated message data; -
a dual mode timer that continually maintains system time while operating in one of an active mode and a sleep mode;
a controller data processor that processes the demodulated message data to produce a digital message;
a reference oscillator that generates a reference clock having a frequency that is high enough to support clocking requirements for digital processing of the receiver and the controller data processor during the active mode, and wherein the frequency of the reference clock is responsive to an automatic frequency control that is input to the reference oscillator;
a sleep oscillator that generates a sleep clock having a frequency that is low relative to the frequency of the reference clock, wherein the sleep oscillator has power consumption that is very low relative to a power consumption of the reference oscillator; and
a controller that supervises operation of the battery operated communication device and that includes;
a scheduler that schedules commands that supervise the battery operated communication device, an event scheduler that receives scheduling commands from the scheduler, the event scheduler including registers for records of scheduled events, each scheduled event comprising a command that initiates a processing event and a scheduled system time for execution of the command, the event scheduler continually monitoring system time for a match with the scheduled system time in any of the records, the match causing execution of the command of the record for which the match occurs; and
a controller frequency tracker that provides the automatic frequency control to the reference oscillator based upon received downconverted signals at the rate of once per digital message reception such that the reference oscillator clock is frequency-locked to the received digital message. - View Dependent Claims (9, 10, 11, 12, 13, 14)
determine a plurality of sleep mode timer calibration settings, each respective to a corresponding temperature;
store the plurality of sleep mode timer calibration settings;
when the measured temperature compares favorably to a stored temperature, retrieve a corresponding sleep mode timer calibration setting; and
apply the retrieved sleep mode timer calibration setting to the dual mode timer.
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Specification
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Current AssigneeAvago Technologies General IP PTE Limited (Broadcom, Inc.)
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Original AssigneeBroadcom Corporation (Broadcom, Inc.)
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InventorsShohara, Aki, Lei, Emilia Vailun
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Primary Examiner(s)Nguyen, Lee
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Application NumberUS10/272,439Publication NumberTime in Patent Office728 DaysField of Search455/208, 455/343--34, 455/255, 455/257, 455/258, 455/259, 455/574, 455/265, 340/7.32, 340/7.38, 370/311, 375/354US Class Current455/343.4CPC Class CodesH04W 52/0216 using a pre-established act...H04W 52/0229 where the received signal i...H04W 52/0293 having a sub-controller wit...H04W 56/0035 detecting errors in frequen...Y02D 30/70 in wireless communication n...
