摘要 |
PURPOSE:To detect the errors and the falsification by adding a specific pattern at the transmitter part and detecting this pattern at the receiver side. CONSTITUTION:A shift register 101 stores a bit pattern showing its internal state and also stores an initial pattern in an initial state. The register 101 also includes a feedback part led from the highest register and this feedback part has its connection structure equal to that used by an M series generator for example. A code converting circuit 102 converts a bit pattern showing the internal state of the register 101 and outputs two bits. An exclusive OR element 103 secures an exclusive OR between one of both bit outputs and an input bit to obtain an output bit. This output bit undergoes an exclusive OR (EOR) with the remaining bits outputted from the circuit 102 through the most significant register of the register 101 and is inputted to the least significant register of the register 101. Then the internal state of the register 101 is changed.
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