Abstract: A method and apparatus for wireless cursor position control is disclosed herein. The apparatus comprises a wireless cursor position device and a separate control base whereby the direction and velocity of motion of the position device is monitored by the control base and used said direction and velocity of motion is to calculate the relative motion of the cursor on the display system. The method and apparatus operates by transmitting and receiving ultrasonic and infrared signals between the position device and control base and thereby calculating the movement of the position device from an initial location by measurement doppler shift of the signals. An output signal to the display system is then generated to move the cursor in correspondence with the motion of the position device.

Abstract: Alignment mark 5 is printed by printer 30 during the same operation in which bar code 3 is printed. Subsequent alignment is by the optical scanner 32 centering on mark 5. In a specific application a factor relating to the vertical position of scanner 32 to printer 30 is obtained by scanning mark 5 shortly after it is printed. This factor is used to position the scanner 32 to read for errors after a line of code 3 is printed.

Abstract: Alignment mark 5 is printed by printer 30 during the same operation in which bar code 3 is printed. Subsequent alignment is by the optical scanner 32 centering on mark 5. In a specific application a factor relating to the vertical position of scanner 32 to printer 30 is obtained by scanning mark 5 shortly after it is printed. This factor is used to position the scanner 32 to read for errors after a line of code 3 is printed.

Abstract: A high density bar code scanned to be read out provides a time varying analog electric signal which after being reshaped is decoded, i.e., converted into a binary bit representation based on distances measured between consecutive leading and consecutive trailing edges of the reshaped analog signal. Errors due to mismeasurements are minimized by using a decoding process based on comparison of each measuring distance to a first or to a second preset threshold level. The choice of the threshold to be used for decoding a given bit depends on the odd or even characteristic of the number of bits previously decoded on the same bit stream. In addition, at least one of the thresholds is dynamically readjusted throughout the process, based on the last measured distance.