Nyquist sampling theorem: If the sampling rate is greater than the analog signal is the maximum frequency of 2 times, can recover the original analog signal samples obtained.
Hamming code: the use of parity for error detection and validation methods. Suppose m-bit information symbol, the k-bit parity code is added, is satisfied m + k + 1 <= 2k , so that the minimum number of bits is inequality of x checksum.