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Hamming (7,4) In coding theory, Hamming (7,4) is a linear error-correcting code that encodes four bits of data into seven bits by adding three parity bits. It is a member of a larger family of Hamming codes, but the term Hamming code often refers to this specific code that Richard W. Hamming introduced in 1950.
In mathematical terms, Hamming codes are a class of binary linear code. For each integer r ≥ 2 there is a code-word with block length n = 2r − 1 and message length k = 2r − r − 1. Hence the rate of Hamming codes is R = k / n = 1 − r / (2r − 1), which is the highest possible for codes with minimum distance of three (i.e., the minimal ...
A SIM lock, simlock, network lock, carrier lock or ( master) subsidy lock is a technical restriction built into GSM and CDMA [ 1] mobile phones by mobile phone manufacturers for use by service providers to restrict the use of these phones to specific countries and/or networks. This is in contrast to a phone (retrospectively called SIM-free or ...
Bootloader unlocking. Bootloader unlocking is the process of disabling the bootloader security that makes secure boot possible. It can make advanced customizations possible, such as installing a custom firmware. On smartphones this can be a custom Android distribution or another mobile operating system.
A personal unblocking key ( PUK ), sometimes called personal unblocking code ( PUC ), is used in SIM cards to reset a personal identification number (PIN) that has been lost or forgotten. Most mobile phones offer the feature of PIN protection. After switching on the phone, if the PIN security function is active, the user is required to enter a ...
The only nontrivial and useful perfect codes are the distance-3 Hamming codes with parameters satisfying (2 r – 1, 2 r – 1 – r, 3), and the [23,12,7] binary and [11,6,5] ternary Golay codes. [4] [5] Another code property is the number of neighbors that a single codeword may have. [6] Again, consider pennies as an example.
The Hamming(7,4) code may be written as a cyclic code over GF(2) with generator + +. In fact, any binary Hamming code of the form Ham(r, 2) is equivalent to a cyclic code, [3] and any Hamming code of the form Ham(r,q) with r and q-1 relatively prime is also equivalent to a cyclic code. [4]
Subsidy Password. The term, Subsidy Password, is used by Motorola and other handset manufacturers to refer to the 8-digit code (or 16-digit code for phones such as the Motorola K1) unlock code necessary to remove the operator lock (also known as subsidy lock) from cell phones. This code is randomly assigned to individual cell phones by the OEM ...