Additive Scrambler: Difference between revisions

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[[Category:Block Docs]]
[[Category:Block Docs]]
[[Category:Stub Docs]]
Scramble an input stream using an LFSR.
This is the template for the [[:Category:Block_Docs|"Page-per-block Docs"]].  This first section should describe what the block does and how to use it, using however many paragraphs necessary.  Note that the title of the wiki page should match the block's name in GRC, i.e. the one defined in the block's .grc file.  Look at the [[FFT]] Block for a good example.


As this is a basic template, it's also in the [[:Category:Stub_Docs|"Stub Docs category"]]. Please improve it.
This block scrambles up to 8 bits per byte of the input data stream, starting at the LSB.
The scrambler works by XORing the incoming bit stream by the output of the LFSR. Optionally, after  bits have been processed, the shift register is reset to the  value. This allows processing fixed length vectors of samples.
 
Alternatively, the LFSR can be reset using a reset tag to scramble variable length vectors. However, it cannot be reset between bytes.
 
For details on configuring the LFSR, see gr::digital::lfsr.


== Parameters ==
== Parameters ==
(''R''): <span class="plainlinks">[https://wiki.gnuradio.org/index.php/GNURadioCompanion#Variable_Controls ''Run-time adjustable'']</span>
(''R''): <span class="plainlinks">[https://wiki.gnuradio.org/index.php/GNURadioCompanion#Variable_Controls ''Run-time adjustable'']</span>


; Param 1 (''R'')
; mask : Polynomial mask for LFSR
: Description of parameter, provide any tips or recommended values.  Note that the name of the parameter above should match the param's label that shows up in grc (e.g. Sample Rate).
; seed
 
: Initial shift register contents
; Param 2
; len
: blah blah blah
: Shift register length
; count
: Number of bytes after which shift register is reset, 0=never
; bits_per_byte
: Number of bits per byte
; reset_tag_key
: When a tag with this key is detected, the shift register is reset (when this is set, count is ignored!)


== Example Flowgraph ==
== Example Flowgraph ==

Revision as of 15:35, 23 July 2019

Scramble an input stream using an LFSR.

This block scrambles up to 8 bits per byte of the input data stream, starting at the LSB. The scrambler works by XORing the incoming bit stream by the output of the LFSR. Optionally, after bits have been processed, the shift register is reset to the value. This allows processing fixed length vectors of samples.

Alternatively, the LFSR can be reset using a reset tag to scramble variable length vectors. However, it cannot be reset between bytes.

For details on configuring the LFSR, see gr::digital::lfsr.

Parameters

(R): Run-time adjustable

mask
Polynomial mask for LFSR
seed
Initial shift register contents
len
Shift register length
count
Number of bytes after which shift register is reset, 0=never
bits_per_byte
Number of bits per byte
reset_tag_key
When a tag with this key is detected, the shift register is reset (when this is set, count is ignored!)

Example Flowgraph

Insert description of flowgraph here, then show a screenshot of the flowgraph and the output if there is an interesting GUI. Currently we have no standard method of uploading the actual flowgraph to the wiki or git repo, unfortunately. The plan is to have an example flowgraph showing how the block might be used, for every block, and the flowgraphs will live in the git repo.

Source Files

C++ files
TODO
Header files
TODO
Public header files
TODO
Block definition
TODO
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