| 摘要 |
Method and apparatus for synchronizing the data transfer rate for downloading data from a cathode ray tube (CRT) adapted for transmission of serial data bits as light pulses appearing as spaced lines on the CRT to a portable information device having a photosensor which receives and stores binary coded data corresponding to the light pulses at a fixed pulse reception rate. The CRT displays a calibration pattern of spaced horizontal lines, which is transmitted to the portable information device where it is repetitively compared to a stored calibration character. An acceptable error free transmission is signaled by a preselected number of matches. An audible signal indicates that the transmission rate is acceptable. The CRT pattern line spacing is adjusted until the audible signal is heard. The selectable pulse repetition rate may be automatically changed in increments by periodically changing the separation between lines on the CRT until an audible output signal is heard and providing for an operator to halt the automatic process. Alternatively, the pulse repetition rate may be manually changed in increments by an operator, until an audible output signal is heard. |
