Hierarchical block for OFDM modulation.
The input is a byte stream (unsigned char) and the output is the complex modulated signal at baseband.
- 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!)
This flowgraph can be found at https://github.com/gnuradio/gnuradio/blob/master/gr-digital/examples/ofdm/ofdm_loopback.grc
- Python files
- Block definition