Robust Tracking of Ultrasonic Pen for Handwriting Digitizer Applications

Lee, Jaejun; Hong, Sang Hoon; Chung, Yunmo

doi:10.1109/tce.2007.4341591

Cited by 4 publications

(2 citation statements)

References 2 publications

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“…These applications require even wider bandwidths than 4 kHz due to the need for accuracy in the mm range, so this has a negative effect on robustness. On the other hand it is an advantage that often in an office environment the noise level can be guaranteed to be less than the maximum used in our analysis, and in particular at higher frequencies such as 80 kHz which is often used [9]. The additional attenuation at the higher frequency plays little role at such low ranges.…”

Section: A Range Predictions For Time Delay Estimatorsmentioning

confidence: 97%

“…Examples are pen digitizers for a writing pad or for a whiteboard. A system for pen tracking for a handwriting digitizer using infrared and ultrasound for time-of-flight estimation is described in [9]. These applications require even wider bandwidths than 4 kHz due to the need for accuracy in the mm range, so this has a negative effect on robustness.…”

Section: A Range Predictions For Time Delay Estimatorsmentioning

confidence: 99%

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Hybrid ultrasound-RFID indoor positioning: Combining the best of both worlds

Holm

2009

2009 IEEE International Conference on RFID

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Abstract-Existing hybrid ultrasound/RF positioning systems usually measure ultrasonic time-of-flight. This operation requires a wide bandwidth and this makes it rather noise sensitive, limiting the useful range. Therefore a new system is proposed where only the room-indicating capability of ultrasound is utilized and combined with RF. A portable tag obtains the room location by receiving a narrow bandwidth signal from a stationary ultrasound transmitter. The result is then relayed back over RF. This combines the high accuracy of ultrasound to pinpoint exactly the room location with the high communications capacity of RF that enables tracking of hundreds of simultaneously moving tags. Secondary parameters that may aid in refining the position such as ultrasound signal level and velocity may also be measured. In addition to the increased capacity, the use of portable receivers instead of transmitters, as in ultrasound-alone indoor positioning systems, also has the advantage of reduced user exposure to ultrasound due to the larger distance to the transmitters.

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Section: A Range Predictions For Time Delay Estimatorsmentioning

confidence: 97%

Section: A Range Predictions For Time Delay Estimatorsmentioning

confidence: 99%