# Nt1310 Unit 1 Exercise 1

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3. Generate Bits: Generates the sequence of data bits to be modulated. This polymorphic VI can generate Fibonacci or Galois pseudonoise (PN) bit sequences. It can also generate bit sequences based on a user-defined pattern. The selected pattern is repeated until the user-specified number of total bits is generated. This polymorphic instance generates Fibonacci pseudonoise (PN) bit sequences. The selected pattern is repeated until the user-specified number of total bits is generated. Use this instance to specify a PN sequence order based on which the VI selects a primitive polynomial that returns an m-sequence. Use this instance to specify the primitive polynomial that determines the connection structure of the linear feedback shift register (LFSR). total bits specifies the total number of pseudorandom bits to be generated. The default value is 128. PN sequence…show more content…
PN sequences are used in many applications and standards such as 802.11a and DVB. Some examples of PN sequences are m-sequences (also called maximal length shift register sequences), Gold sequences, and Kasami sequences. An m-sequence generates a periodic sequence of length L = 2m – 1 bits and is generated by Linear Feedback Shift Registers (LFSR). Two very well known implementations of m-sequences are the Fibonacci implementation and the Galois implementation. The preceding figures shows the Fibonacci and Galois implementations of maximal length shift register m-sequences. As can be seen in these figures, m-sequences contain m shift registers. The shift register set is filled with an m-bit initial seed that can be any value except 0 (if the m bits in the m shift registers are all zero, then it is a degenerate case and the output of the generator is 0).
The following examples demonstrate bit generation.
1. Inputs are specified as