Channel Model: Difference between revisions

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; Frequency Offset (''R'')
; 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.
: The normalized frequency offset. 0 is no offset; 0.25 would be, for example, one quarter of a sample time.


; Epsilon (''R'')
; Epsilon (''R'')
Line 15: Line 15:


; Taps (''R'')
; 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.
: Taps of a FIR filter to emulate a multipath delay profile.  Default is 1+0j meaning a single tap, and thus no multipath.


; Seed
; Seed
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== Example Flowgraph ==
== Example Flowgraph ==


This flowgraph is taken from the [[Guided_Tutorial_PSK_Demodulation]] tutorial.
This flowgraph is taken from the [[QPSK_Mod_and_Demod]] tutorial.


[[File:Stage2_grc.png|874px|]]
[[File:Qpsk_stage2_fg.png|800px|]]


[[File:Stage2.png|925px|]]
[[File:Qpsk_stage2_out.png|800px|]]


== Source Files ==
== Source Files ==
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; Header files
; Header files
: [https://github.com/gnuradio/gnuradio/blob/master/gr-channels/lib/channel_model2_impl.h /gr-channels/lib/channel_model_impl.h]
: [https://github.com/gnuradio/gnuradio/blob/master/gr-channels/lib/channel_model_impl.h /gr-channels/lib/channel_model_impl.h]


; Public header files
; Public header files

Latest revision as of 14:49, 9 December 2023

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

(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 example, one quarter of a sample time.
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+0j 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

This flowgraph is taken from the QPSK_Mod_and_Demod tutorial.

Qpsk stage2 fg.png

Qpsk stage2 out.png

Source Files

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