Radiolocation system having writing pen application
First Claim
1. A radiolocation system for tracking a wireless moving object, comprising:
- a transmitter, integral with the moving object, for transmitting a plurality of RF bursts at a transmit PRF;
a plurality of receivers, at known relative positions, for receiving the RF bursts upon receipt of gating pulses and outputting a digital representation of the received RF bursts; and
circuitry for generating a plurality of gating pulses at the transmit PRF and swept in time relative to the transmit RF bursts, and for supplying the gating pulses substantially simultaneously to each of the receivers, each of the receivers then receiving the RF bursts for the duration of the gating pulses.
2 Assignments
0 Petitions
Accused Products
Abstract
Two or more receivers of known location receive RF bursts from a wireless moving object containing a transmitter that transmits periodic RF bursts. The receivers are gated with precision swept timing that repeats at the exact transmit RF burst period to produce precision expanded time representations of the received RF bursts. The expanded time representations correspond to RF burst arrival times from the transmitter, which are used to calculate the location of the transmitter. A writing pen application includes an RF transmitter in a writing pen and four RF receivers beneath the surface of a writing tablet where RF propagation from the pen to the receivers cannot be blocked by a user'"'"'s hand. Two RF transmitters, one located at each end of the pen, may be employed to measure pen tilt and for 3-D tracking. Spatial resolution is more than 600 dpi at 100 location fixes per second.
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Citations
21 Claims
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1. A radiolocation system for tracking a wireless moving object, comprising:
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a transmitter, integral with the moving object, for transmitting a plurality of RF bursts at a transmit PRF;
a plurality of receivers, at known relative positions, for receiving the RF bursts upon receipt of gating pulses and outputting a digital representation of the received RF bursts; and
circuitry for generating a plurality of gating pulses at the transmit PRF and swept in time relative to the transmit RF bursts, and for supplying the gating pulses substantially simultaneously to each of the receivers, each of the receivers then receiving the RF bursts for the duration of the gating pulses. - View Dependent Claims (2, 3, 4, 5)
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6. A method for tracking a wireless moving object, comprising:
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transmitting a plurality of RF bursts at a PRF from the moving object;
providing a plurality of receivers at known relative positions;
generating a plurality of gating pulses at the PRF and sweeping the occurrence time of the gating pulses relative to the RF bursts;
receiving the RF bursts, at each of the receivers; and
producing digital representations of the RF bursts in response to the gating pulses. - View Dependent Claims (7, 8)
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9. A handwriting digitization system comprising:
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a wireless pen including a transmitter for transmitting a plurality of RF bursts at a PRF;
a plurality of receivers, each having an antenna at a known position for receiving RF bursts upon receipt of a gating pulse and outputting a digital representation of the received RF bursts;
circuitry for generating a plurality of gating pulses at the PRF and swept in time relative to the RF bursts, and for supplying the gating pulses substantially simultaneously to the receivers, the receivers then receiving the RF bursts in response to the gating pulses. - View Dependent Claims (10, 11)
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12. A method of digitizing handwriting written by a user using a wireless pen, comprising:
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transmitting, from the wireless pen, a plurality of RF bursts at a PRF;
providing a plurality of receivers, each of the receivers having an antenna at a known position;
generating a plurality of gating pulses at the PRF which are swept in time relative to the RF bursts, each of the gating pulses having a duration;
receiving the RF bursts at each of the receivers within the durations of the gating pulses;
producing digital representations of the RF bursts received by the receivers. - View Dependent Claims (13, 14, 15)
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16. A radiolocation system for tracking a wireless moving object, comprising:
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a transmitter, integral with the moving object, for transmitting a plurality of RF bursts at a transmit PRF;
a plurality of receivers, at known relative positions, for receiving the RF bursts upon receipt of gating pulses and outputting a digital representation of the received RF bursts;
a receive PRF generator for receiving a digital representation from a receiver and for providing a PRF at the exact frequency of the transmit PRF;
a timing sweep coupled to the receive PRF generator for sweeping the gating pulses over a range of delays relative to the transmitted RF bursts; and
a gate generator coupled to the timing sweep for generating a plurality of gating pulses at the transmit PRF and swept in time relative to the transmit RF bursts, and for supplying the gating pulses substantially simultaneously to each of the receivers, each of the receivers then receiving the RF bursts for the duration of the gating pulses. - View Dependent Claims (17, 18)
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19. A method for tracking a wireless moving object, comprising:
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transmitting a plurality of RF bursts at a transmit PRF from the moving object;
providing a plurality of receivers at known relative positions;
locking a receive PRF generator to the exact frequency of the transmit PRF;
generating a plurality of gating pulses having a duration at the transmit PRF;
sweeping the occurrence time of the gating pulses relative to the RF bursts;
receiving the RF bursts during the duration of the gating pulses at each of the receivers;
producing digital representations of the RF bursts in response to the gating pulses. - View Dependent Claims (20, 21)
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Specification