Abstract: A compact low-power radio frequency (RF) transceiver with a built-in antenna provides wireless communication between a computer and another device. A direct conversion receiver together with a voltage controlled oscillator, phase lock loop circuits, digitally controlled divider circuits and a patch antenna are packaged into a compact enclosure, having dimensions within the PCMCIA format. In some embodiments, the transceiver enters a sleep mode whenever it is idle in order to further conserve power. In other embodiments, a signature detector enables the transceiver to distinguish between noise and valid messages by recognizing a signature word embedded in the data packet.

Abstract: A digitizer uses acoustic waves originating from a stylus to determine the position of the stylus on a plate. The acoustic waves are introduced into the plate from the tip of the stylus and are detected by a plurality of detectors positioned at various points along the periphery of the plate. By sensing differences in the arrival times of the acoustic waves at the detectors, a microprocessor calculates the position of the stylus. In a preferred embodiment using a non-tethered stylus, four detectors are positioned at the corners of a rectangle, and the time differences are used as addresses in a lookup table, which is programmed to contain x and y coordinates corresponding to the time differences, Different embodiments may detect only the "fast" symmetrical waves or only the "slow" antisymmetrical waves generated in the plate, or may use the arrival times of both types of waves to determine the stylus position.