- pseudorandom sequence generator
- *** 밑에 분류 무시
- 2008. 2. 25. 12:44
purely random sequence can be used to spread the signal spectrum. however, in order to despread the signal, the receiver needs a replica of the transmitted sequence (in most perfect time synchronism). in practice, therefore, we generate pseudorandom or pseudonoise (PN) sequence. 1
linear feedback shift register (LFSR)
- one canonical form of a 'binary LFSR' is a 'simple shift register generator (SSRG)'
the shift register consists of binary storage elements (boxes) which transfer their contents to the right after each clock pulse. the contents of the register are linearly combined with the binary (0, 1) coefficients
and are fed back to the first stage.
- for spread spectrum, we are looking for a maximal length cycles (maximum length sequence, MLLFSR) 2
if the initial state of the shift register is 0 0 0 1, then the output (from position 4) at each state would be 1 0 0 0 1 1 1 1 0 1 0 1 1 0 0.
- modular shift register generator (MSRF), which is commonly used implementation of a LFSR
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