The Descrambler block descrambles a scalar or column vector input signal. The Descrambler block is the inverse of the Scrambler block. If you use the Scrambler block in a transmitter, then you use the Descrambler block in the related receiver.
In the following descrambler schematic, the adders and subtracter operate modulo N, where N is the Calculation base parameter. You must specify integer input values between 0 and N-1.
At each time step, the input causes the contents of the registers to shift sequentially. Using the Scramble polynomial parameter, you specify if each switch in the descrambler is on or off. To make the Descrambler block reverse the operation of the Scrambler block, use the same Scramble polynomial parameters in both blocks. If there is no signal delay between the scrambler and the descrambler, then the Initial states in the two blocks must be the same. See the reference page for the Scrambler block for more information about these parameters. There is an optional port that can be used to reset the descrambler.
Alternatively, the initial states can be provided by an input port when Initial states source parameter is set to Input port.
This block can accept input sequences that vary in length during simulation. For more information about sequences that vary in length, or variable-size signals, see Variable-Size Signal Basics in the Simulink® documentation.
The calculation base N. The input and output of this block are integers in the range [0, N-1].
A polynomial that defines the connections in the scrambler.
A drop down menu that controls the source of the initial states. Select either Dialog Parameter or Input port. The default value is Dialog Parameter.
The states of the descrambler's registers when the simulation starts. This parameter is available when Initial states source is set to Dialog Parameter.
A check box that creates a reset port. When checked, the descrambler is reset if a nonzero input is applied to the port. This control is available when Initial states source is set to Dialog Parameter. The default is that the box is not checked.