OFDM Receiver: Difference between revisions

From GNU Radio
Jump to navigation Jump to search
(Created page with "Category:Block Docs Category:Stub Docs This is the template for the "Page-per-block Docs". This first section should describe what the block...")
 
 
(8 intermediate revisions by 3 users not shown)
Line 1: Line 1:
[[Category:Block Docs]]
[[Category:Block Docs]]
[[Category:Stub Docs]]
Hierarchical block for OFDM demodulation.
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.
The input is a complex baseband signal (e.g. from a UHD source).
The detected packets are output as a stream of packed bits on the output.


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


; Param 1 (''R'')
; FFT Length
: 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).
: The length of FFT (integer).


; Param 2
; Cyclic Prefix Length
: blah blah blah
: The length of cyclic prefix in total samples (integer).
 
; Packet Length Tag Key
: The name of the tag giving packet length at the input.
 
; Occupied Carriers
: A vector of vectors describing which OFDM carriers are occupied with data symbols. occupied_carriers[0] identifies the carriers that are used for the first OFDM symbol, and so on.
 
; Pilot Carriers
: A vector of vectors describing which OFDM carriers are occupied with pilot symbols.
 
; Pilot Symbols
: A vector of vectors indicating the pilot symbols.
 
; Sync Word 1
: The first sync preamble symbol. This has to be with zeros on alternating carriers. Used for fine and coarse frequency offset and timing estimation.
 
; Sync Word 2
: The second sync preamble symbol. This has to be filled entirely. Also used for coarse frequency offset and channel estimation.
 
; Header Modulation
: It has two options:
:* BPSK (Binary Phase Shift Keying)
:* QPSK (Quadrature Phase Shift Keying)
 
; Payload Modulation
: It has three options:
:* BPSK (Binary Phase Shift Keying)
:* QPSK (Quadrature Phase Shift Keying)
:* 8-PSK (Eight Phase Shift Keying)
 
; Scramble Bits
: Activates the scramblers (set this to True unless debugging)
 
; Log Debug Info
: Write output into log files (Warning: creates lots of data!)


== 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.
This flowgraph can be found at https://github.com/gnuradio/gnuradio/blob/master/gr-digital/examples/ofdm/ofdm_loopback.grc
 
[[File:Ofdm_loopback_example_fg.png|807px]]


== Source Files ==
== Source Files ==


; C++ files
; Python file
: [https://github.com/gnuradio/gnuradio TODO]
: [https://github.com/gnuradio/gnuradio/blob/main/gr-digital/python/digital/ofdm_txrx.py ofdm_txrx.py]
 
; Header files
: [https://github.com/gnuradio/gnuradio TODO]
 
; Public header files
: [https://github.com/gnuradio/gnuradio TODO]


; Block definition
; Block definition
: [https://github.com/gnuradio/gnuradio TODO]
: [https://github.com/gnuradio/gnuradio/blob/main/gr-digital/grc/digital_ofdm_rx.block.yml digital_ofdm_rx.block.yml]

Latest revision as of 13:23, 1 June 2022

Hierarchical block for OFDM demodulation.

The input is a complex baseband signal (e.g. from a UHD source). The detected packets are output as a stream of packed bits on the output.

Parameters

FFT Length
The length of FFT (integer).
Cyclic Prefix Length
The length of cyclic prefix in total samples (integer).
Packet Length Tag Key
The name of the tag giving packet length at the input.
Occupied Carriers
A vector of vectors describing which OFDM carriers are occupied with data symbols. occupied_carriers[0] identifies the carriers that are used for the first OFDM symbol, and so on.
Pilot Carriers
A vector of vectors describing which OFDM carriers are occupied with pilot symbols.
Pilot Symbols
A vector of vectors indicating the pilot symbols.
Sync Word 1
The first sync preamble symbol. This has to be with zeros on alternating carriers. Used for fine and coarse frequency offset and timing estimation.
Sync Word 2
The second sync preamble symbol. This has to be filled entirely. Also used for coarse frequency offset and channel estimation.
Header Modulation
It has two options:
  • BPSK (Binary Phase Shift Keying)
  • QPSK (Quadrature Phase Shift Keying)
Payload Modulation
It has three options:
  • BPSK (Binary Phase Shift Keying)
  • QPSK (Quadrature Phase Shift Keying)
  • 8-PSK (Eight Phase Shift Keying)
Scramble Bits
Activates the scramblers (set this to True unless debugging)
Log Debug Info
Write output into log files (Warning: creates lots of data!)

Example Flowgraph

This flowgraph can be found at https://github.com/gnuradio/gnuradio/blob/master/gr-digital/examples/ofdm/ofdm_loopback.grc

Ofdm loopback example fg.png

Source Files

Python file
ofdm_txrx.py
Block definition
digital_ofdm_rx.block.yml
Retrieved from "https://wiki.gnuradio.org/index.php?title=OFDM_Receiver&oldid=12321"