| Communications Blockset™ | ![]() |
Sequence Generators sublibrary of Comm Sources
Barker codes, which are subsets of PN sequences, are commonly used for frame synchronization in digital communication systems. Barker codes have length at most 13 and have low correlation sidelobes. A correlation sidelobe is the correlation of a codeword with a time-shifted version of itself. The correlation sidelobe, Ck, for a k-symbol shift of an N-bit code sequence, {Xj}, is given by

where Xj is an individual code symbol taking values +1 or -1 for j=1, 2, 3,..., N, and the adjacent symbols are assumed to be zero.
The Barker Code Generator block provides the codes listed in the following table:
| Code length | Barker Code |
|---|---|
| 1 | [-1] |
| 2 | [-1 1]; |
| 3 | [-1 -1 1] |
| 4 | [-1 -1 1 -1] |
| 5 | [-1 -1 -1 1 -1] |
| 7 | [-1 -1 -1 1 1 -1 1] |
| 11 | [-1 -1 -1 1 1 1 -1 1 1 -1 1] |
| 13 | [-1 -1 -1 -1 -1 1 1 -1 -1 1 -1 1 -1] |

Opening this dialog box causes a running simulation to pause. See Changing Source Block Parameters in the online Simulink documentation for details.
The length of the Barker code.
Period of each element of the output signal.
Determines whether the output is frame-based or sample-based.
The number of samples in a frame-based output signal. This field is active only if you select the Frame-based outputs check box.
The output type of the block can be specified as an int8 or double. By default, the block sets this to double.
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