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Common PRNG (pseudorandom number generator) — preferably cryptographically secure — in both transmitter and receiver; Transmitter sends 'next' code in sequence; Receiver compares 'next' to its calculated 'next' code. A typical implementation compares within the next 256 codes in case receiver missed some transmitted keypresses.
The block length of a block code is the number of symbols in a block. Hence, the elements c {\displaystyle c} of Σ n {\displaystyle \Sigma ^{n}} are strings of length n {\displaystyle n} and correspond to blocks that may be received by the receiver.
In addition to the PRN ranging codes, a receiver needs to know the time and position of each active satellite. GPS encodes this information into the navigation message and modulates it onto both the C/A and P(Y) ranging codes at 50 bit/s. The navigation message format described in this section is called LNAV data (for legacy navigation).
The transmitter keeps track of the running DC buildup, and picks the code word that pushes the DC level back towards zero. The receiver is designed so that either code word of the pair decodes to the same data bits. Examples of paired disparity codes include alternate mark inversion, 8b/10b and 4B3T. Use a scrambler.
Code-division multiple access (CDMA) is a channel access method used by various radio communication technologies. CDMA is an example of multiple access, where several transmitters can send information simultaneously over a single communication channel.
The number encoded in a selcall burst is used to address one or more receivers. If the receiver is programmed to recognise a certain number, then it will un-mute its speaker so that the transmission can be heard; an unrecognised number is ignored and therefore the receiver remains muted.
In fact such codes are typically constructed to correct only a small fraction of errors with a high probability, but achieve a very good rate. The first such code was due to George D. Forney in 1966. The code is a concatenated code by concatenating two different kinds of codes.
Hence the rate of Hamming codes is R = k / n = 1 − r / (2 r − 1), which is the highest possible for codes with minimum distance of three (i.e., the minimal number of bit changes needed to go from any code word to any other code word is three) and block length 2 r − 1.