| 摘要 |
PURPOSE:To determine the position of an error and to correct the error by setting two strings of check points and comparing codes of the check points with codes which are obtained newly from information digits according to parity check items. CONSTITUTION:Check points where a corrected check code change by an erroneous digit 13 are only a pair of H1 and S2. When the check code begins changing at H1, the change continues up to H2 along a check sequence (arrow). At this time, two kinds of check points exist on two check lines 5 and 6 respectively. When the check code beings changing at S2, the check codes change until S1 and two kinds of check points exist similarly. The erroneous digit and two kinds of check point exist on the same check line, so a closed chain is formed. Those check points form a chain with other check points of the same kind, and the check points discriminated in two kinds form the mutually independent chains with the erroneous digit, respectively. Those chains are used to determine the position of the erroneous digit, correcting the error. |
