OFDM Transmitter

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Hierarchical block for OFDM modulation.

The input is a byte stream (unsigned char) and the output is the complex modulated signal at baseband.

Parameters[edit]

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.
Pilot Carriers
A vector of vectors describing which OFDM carriers are occupied with pilot symbols.
Pilot Symbols
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
Payload Modulation
Rolloff length (samples)
The rolloff length in samples. Must be smaller than the CP.
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[edit]

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[edit]

Python files
[1]
Block definition
[2]