Hi, I have connected benchmark_tx.py and benchmark_rx.py to make it loopback mode without USRPs. There is no channel block between the tx and rx chain.
I checked all blocks in the Transmit chain. All are working as expected. But in Receiver chain i did not understand the output of *ofdm_sync_ml *and *digital.ofdm_sampler * blocks. I tried checking the output of port 1 of ofdm_sync. The sync signal is one on the following indexes: * 714, 7109, 13515, 19911, 26308, 32705, 39115, 45515,* * 51910, 58315, 64715, 71115, 77515, 83915, 90315, 96712,* * 103115, 109512, 115910, 122315, 128715, 135113, 141510, 147915,* * 154288, 160711, 167112, 173515, 179912, 186315* I checked the output of port 1 of ofdm_sampler. The sync signal is one on the following indexes: *0, 5120, 10752, 15872, 20992, 26112, 31744, 36864,* * 41984, 47616, 52736, 57856, 62976, 68096, 73216, 78336,* * 83968, 89088, 94208, 99840, 104960, 110080, 115200, 120832,* * 125952, 131584, 136704, 142336, 147456, 153088* *I expected the output of *port 1 of ofdm_sync to be 639, 639+6400, 639+12800 , ... and output of port 1 of ofdm_sampler to be 0, 5120, 5120*2, 5120*3, .... General parameters are as follows: fft_len = 512 cp_len = 128 occupied_tones = 200 modulation = bpsk pkt_size = 200 bytes after CRC and Header pkt_length = 209 bytes 1 sync word for each packet Finally there will be 10 OFDM symbols per pkt and 512+128 = 640 complex symbols per OFDM symbol.
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