Watchdog circuit of vehicle tracking system
First Claim
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1. A watchdog circuit of a vehicle tracking system, comprising:
- a microcomputer;
a code modulation and amplification circuit;
a high-frequency power amplifier;
a first timer for transmitting a first timed signal by counting during a time period for transmitting two frames of tracking data after receiving a power amplification control signal from said microcomputer;
a first logic gate for generating a transmission interruption control signal for said high-frequency power amplifier in response to said first timed signal counted during the time for transmitting two frames by said first timer and said power amplification control signal from said microcomputer;
a driving circuit for turning off said high-frequency power amplifier in response to said transmission interruption control signal from said first logic gate;
a second timer for transmitting a second timed signal for a frame transmission time after receiving said first timed signal counted during the time for transmitting two frames; and
a reset signal generator for generating a reset signal for resetting said microcomputer in response to said second timed signal counted for a frame transmission time by said second timer and said power amplification control signal from said microcomputer.
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Abstract
Disclosed is a watchdog circuit of a vehicle tracking system for resetting a microcomputer by sensing a transmission time longer than a predetermined time owing to a false operation of a vehicle mounted equipment in case of transmitting a position signal, and for preventing a malfunction of a vehicle tracking system.
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Citations
25 Claims
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1. A watchdog circuit of a vehicle tracking system, comprising:
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a microcomputer; a code modulation and amplification circuit; a high-frequency power amplifier; a first timer for transmitting a first timed signal by counting during a time period for transmitting two frames of tracking data after receiving a power amplification control signal from said microcomputer; a first logic gate for generating a transmission interruption control signal for said high-frequency power amplifier in response to said first timed signal counted during the time for transmitting two frames by said first timer and said power amplification control signal from said microcomputer; a driving circuit for turning off said high-frequency power amplifier in response to said transmission interruption control signal from said first logic gate; a second timer for transmitting a second timed signal for a frame transmission time after receiving said first timed signal counted during the time for transmitting two frames; and a reset signal generator for generating a reset signal for resetting said microcomputer in response to said second timed signal counted for a frame transmission time by said second timer and said power amplification control signal from said microcomputer. - View Dependent Claims (2)
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3. A cut-off circuit of a vehicle tracking system having a central control station, said cut-off circuit comprising:
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microprocessing means for generating a control signal and a power amplification control signal; code modulation and amplification means for generating a modulated signal by modulating and amplifying an intermediate signal in response to said control signal; high frequency amplification means for amplifying said modulated signal for transmission via an antenna to said central control station; first timing means for generating a first timed signal for a first predetermined time period in response to said power amplification control signal; first logic means for generating a transmission interruption control signal in response to said first timed signal and said power amplification control signal; driving means for turning off said high frequency amplification means to disable transmission of said modulated signal in response to said transmission interruption control signal; second timing means for generating a second timed signal a second predetermined time period after said first timed signal; and reset signal generating means for resetting said microprocessing means from a first mode to a second mode in response to said second timed signal and said power amplification control signal. - View Dependent Claims (4, 5, 6, 7, 8, 9, 10, 16, 17)
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11. A cut-off circuit of a vehicle tracking system including a central control station, said cut-off circuit comprising:
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microprocessing means for generating a control signal and a power amplification control signal during a transmission mode for transmission of tracking data; code modulation and amplification means for generating a modulated signal by amplifying and modulating an intermediate signal in response to said control signal; high frequency amplification means for amplifying a high frequency component of said modulated signal and transmitting the amplified high frequency component via an antenna to the central control station; transmission interruption means for turning off said high frequency amplification means after a first time interval counted from the generation of said power amplification control signal, said transmission interruption means comprising first timing means for generating a first timed signal in response to said power amplification control signal, first logic means for generating a transmission interruption control signal in response to said first timed signal and said power amplification control signal, and driving means for turning off said high frequency amplification means in response to said transmission interruption control signal; second timing means for generating a second timed signal after said first time interval; and mode reset means, connected to said transmission interruption means and said microprocessing means, responsive to said second timing means for resetting said microprocessing means from said transmission mode to a non-transmission mode in response to said second timed signal. - View Dependent Claims (12)
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13. A cut-off circuit of a vehicle tracking system including a central control station, said cut-off circuit comprising:
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microprocessing means for generating a control signal and a power amplification control signal during a transmission mode for transmission of tracking data; code modulation and amplification means for generating a modulated signal by amplifying and modulating an intermediate signal in response to said control signal; high frequency amplification means for amplifying a high frequency component of said modulated signal and transmitting the amplified high frequency component via an antenna to the central control station; first timing means for generating a first timed signal for a first interval that is substantially equal to a time period for transmission of two frames of tracking data to the central control station, in response to said power amplification control signal; first logic means for generating a transmission interruption control signal in response to said first timed signal and said power amplification control signal; driving means for turning off said high frequency amplification means in response to said transmission interruption control signal; second timing means for generating a second timed signal for a second interval that is substantially equal to a time period for transmission of one frame of tracking data to the central control station, after said first interval in response to said first timed signal; and reset signal generating means for resetting said microprocessing means from said transmission mode to a non-transmission mode during said second interval in response to continued generation of said power amplification control signal after said first interval. - View Dependent Claims (14, 15, 18)
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19. A process for preventing malfunction of a vehicle tracking device including a microcomputer for generating a power amplification control signal during a transmission mode for transmission of tracking data, a modulator responsive to said microcomputer for modulating pseudo random code to generate pseudo random code signals, and a high frequency power amplifier for amplifying said pseudo random code signals for transmission to a central control station, said process including:
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counting a transmission time of two successive frames of track data for a first time period by a first timer in response to said power amplification control signal; disabling operation of said high frequency power amplifier from transmitting said pseudo random code signals to the central control station in response to expiration of said first time period; counting a transmission time of a single frame of track data for a second time period by a second timer in response to expiration of said first time period; and generating a reset signal for resetting said microcomputer from said transmission mode to a non-transmission mode upon initiation of said second time period in response to continued generation of said power amplification control signal by said microcomputer during said second time period. - View Dependent Claims (20, 21)
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22. A vehicle tracking device including a central control station, comprising:
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first means for generating a modulation control signal and a power amplification control signal during a first operational mode enabling transmission of tracking data; second means for modulating pseudo random code signals indicative of said tracking data in response to said modulation control signal; third means for amplifying said modulated pseudo random code signals for radio frequency transmission to the central control station; fourth means comprising a first timer for generating a first counting signal continuously for only a first time period counted in response to generation of said power amplification control signal; fifth means comprising a first logic gate for generating a transmission interruption control signal in response to a logical combination of said first counting signal and said power amplification control signal to disable said third means from amplifying said pseudo random code signals for radio frequency transmission to the central control station when said first counting signal indicates expiration of said first time period; and sixth means for responding to said power amplification control signal after indication by said first counting signal of said expiration of said first time period by generating a reset signal to reset said first means from said first operational mode to a second operational mode discontinuing generation of said modulation control signal and said power amplification control signal. - View Dependent Claims (23, 24, 25)
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Specification