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Method and apparatus for synchronizing data transfer rate from a cathode ray tube video monitor to a portable information device

  • US 5,570,297 A
  • Filed: 05/31/1994
  • Issued: 10/29/1996
  • Est. Priority Date: 05/31/1994
  • Status: Expired due to Fees
First Claim
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1. A method 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 at a selectable pulse repetition rate to a portable information device having a photosensor responsive to said light pulses with means adapted to receive and store binary coded data corresponding to said light pulses at least one fixed pulse reception rate comprising:

  • (a) providing calibration output signal means in said portable information device,(b) storing a calibration character comprising a block of binary coded data in said portable information device,(c) transmitting a block of serial data bits corresponding to said calibration character in the form of light pulses appearing as spaced lines on the CRT,(d) receiving said block of serial data bits via said photosensor on said portable information device,(e) comparing said received serial data bits with said stored calibration character,(f) activating said calibration output signal means after receiving at least one match of the received data bits with the stored calibration character, and(g) selecting a new pulse repetition rate by changing the line spacing of said spaced lines corresponding to said calibration character on the CRT and repeating steps (c) through (e) in the absence of a signal from said calibration output signal means, until said new repetition rate of the CRT data transmission may be received at the fixed pulse reception rate of the portable information device.

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