| 摘要 |
To transmit handwritten recordings, only the initial coordinates of a line trace are usually transmitted as absolute values in PCM coding. Up to a predetermined rate of movement which is determined by a maximum difference DELTA max between two coordinate values (x and y), only the difference from the in each case preceeding coordinate value (x and y) is transmitted in DPCM coding for the subsequently scanned coordinate value pairs (x, y). If the predetermined rate of movement, and thus DELTA max, is exceeded, even if only for a short time, at least the following coordinate value pair (x, y) is transmitted in PCM coding. According to the invention, the coordinate value pairs (x, y) are scanned with an increased clock repetition rate (fA). Up to the predetermined rate of movement, only the coded coordinate value pairs (x, y) with odd ordinal number, following the initial coordinate value pair, are transmitted in DPCM coding at half the fA rate (fAU). If the predetermined rate of movement, and thus DELTA max, is exceeded, the coded coordinate value pairs (x, y) of even ordinal number are inserted in DPCM coding by the control circuit (SS1). The following coordinate value pair (x, y) of odd ordinal number is only transmitted in PCM coding when the code difference between two coordinate values (x or y) of odd ordinal number exceeds 2 . DELTA max. <IMAGE>
|
