Difference between revisions of "Channel Model"

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[[Category:Block Docs]]
 
[[Category:Block Docs]]
[[Category:Stub Docs]]
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A basic channel model simulator that can be used to help evaluate, design, and test various signals, waveforms, and algorithms.  This model allows the user to set the voltage of an AWGN noise source (), a (normalized) frequency offset (), a sample timing offset (), and a seed () to randomize or make reproducible the AWGN noise source. Multipath can be approximated in this model by using a FIR filter representation of a multipath delay profile with the parameter. To simulate a channel with time-variant channel, use [[Channel Model 2]].
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.
 
  
 
== 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'')
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; Noise Voltage (''R'')
: 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).
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: The AWGN noise level as a voltage (to be calculated externally to meet, say, a desired SNR).
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; Frequency Offset (''R'')
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: The normalized frequency offset. 0 is no offset; 0.25 would be, for a digital modem, one quarter of the symbol rate.
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; Epsilon (''R'')
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: The sample timing offset to emulate the different rates between the sample clocks of the transmitter and receiver. 1.0 is no difference.
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; Taps (''R'')
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: Taps of a FIR filter to emulate a multipath delay profile. Default is 1+1j meaning a single tap, and thus no multipath.
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; Seed
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: A random number generator seed for the noise source.
  
; Param 2
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; Block Tag Propagation
: blah blah blah
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: If true, tags will not be able to propagate through this block.
  
 
== Example Flowgraph ==
 
== 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.
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This flowgraph is taken from the [[Guided_Tutorial_PSK_Demodulation]] tutorial.
  
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[[File:Stage2_grc.png|874px|]]
  
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[[File:Stage2.png|925px|]]
  
 
== Source Files ==
 
== Source Files ==
  
 
; C++ files
 
; C++ files
: [https://github.com/gnuradio/gnuradio TODO]
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: [https://github.com/gnuradio/gnuradio/blob/master/gr-channels/lib/channel_model_impl.cc /gr-channels/lib/channel_model_impl.cc]
  
 
; Header files
 
; Header files
: [https://github.com/gnuradio/gnuradio TODO]
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: [https://github.com/gnuradio/gnuradio/blob/master/gr-channels/lib/channel_model2_impl.h /gr-channels/lib/channel_model_impl.h]
  
 
; Public header files
 
; Public header files
: [https://github.com/gnuradio/gnuradio TODO]
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: [https://github.com/gnuradio/gnuradio/blob/master/gr-channels/include/gnuradio/channels/channel_model.h /gr-channels/include/gnuradio/channels/channel_model.h]
  
 
; Block definition
 
; Block definition
: [https://github.com/gnuradio/gnuradio TODO]
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: [https://github.com/gnuradio/gnuradio/blob/master/gr-channels/grc/channels_channel_model.block.yml /gr-channels/grc/channels_channel_model.block.yml]

Latest revision as of 10:26, 25 November 2020

A basic channel model simulator that can be used to help evaluate, design, and test various signals, waveforms, and algorithms. This model allows the user to set the voltage of an AWGN noise source (), a (normalized) frequency offset (), a sample timing offset (), and a seed () to randomize or make reproducible the AWGN noise source. Multipath can be approximated in this model by using a FIR filter representation of a multipath delay profile with the parameter. To simulate a channel with time-variant channel, use Channel Model 2.

Parameters[edit]

(R): Run-time adjustable

Noise Voltage (R)
The AWGN noise level as a voltage (to be calculated externally to meet, say, a desired SNR).
Frequency Offset (R)
The normalized frequency offset. 0 is no offset; 0.25 would be, for a digital modem, one quarter of the symbol rate.
Epsilon (R)
The sample timing offset to emulate the different rates between the sample clocks of the transmitter and receiver. 1.0 is no difference.
Taps (R)
Taps of a FIR filter to emulate a multipath delay profile. Default is 1+1j meaning a single tap, and thus no multipath.
Seed
A random number generator seed for the noise source.
Block Tag Propagation
If true, tags will not be able to propagate through this block.

Example Flowgraph[edit]

This flowgraph is taken from the Guided_Tutorial_PSK_Demodulation tutorial.

Stage2 grc.png

Stage2.png

Source Files[edit]

C++ files
/gr-channels/lib/channel_model_impl.cc
Header files
/gr-channels/lib/channel_model_impl.h
Public header files
/gr-channels/include/gnuradio/channels/channel_model.h
Block definition
/gr-channels/grc/channels_channel_model.block.yml