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diff --git a/gnuradio-examples/python/digital-bert/README b/gnuradio-examples/python/digital-bert/README deleted file mode 100644 index 83f52f4f5..000000000 --- a/gnuradio-examples/python/digital-bert/README +++ /dev/null @@ -1,63 +0,0 @@ -BERT testing example scripts - - -benchmark_tx.py - -This sets up a BPSK transmitter that is modulated with a pseudorandom -sequence of bits. The PN code is generated by sending an all 1s -sequence through a 7-bit scrambler. The transmitter performs the BPSK -modulation, then passes the complex baseband waveform through a -root-raised-cosine filter and onto the USRP. - -The --sps parameter controls how many baseband samples per symbol -are created and passed through the RRC filter, prior to going to the -USRP over the USB for interpolation to the final DAC rate. - -The baseband bit rate is controlled by -r or --rate. This value, when -multiplied by the --sps parameter, must result in valid interpolation -rate for the USRP. For example, if the baseband rate is 250k bits/sec, -and the samples per symbol is 4, then the final rate is 1M samples/sec, -which results in an interpolation rate of 128. The valid interpolation -rates for the USRP are multiples of 4 between 16 and 512. - -Finally, the RRC excess bandwidth may be specified by --excess-bw. -(See ./benchmark_tx.py -h for additional parameters.) - - -benchmark_rx.py - -This sets up a BPSK receiver to demodulate the received waveform. It -accepts a similar set of parameters as the transmitter, except that one -specifies the USRP decimation rate desired. The resulting sample stream -rate must be an integral number of baseband symbols. For example, the -parameters corresponding to the above transmitter would be to use a -decimation rate of 8 (32 sps), 16 (16 sps), 32 (8 sps), 64, (4 sps), or -128 (2 sps). The lower the USRP decimation, the more CPU is required to -demodulate the signal, so not all valid decimation rates will work. - -The baseband signal from the USRP is first passed through an AGC to -establish an average power of 1.0. It is then passed through a matched -filter (another RRC), a Costas phase-locked loop, and a Mueller and -Muller bit timing recovery loop. The resulting constellation has an SNR -estimation probe attached, and is then sliced into a bit stream. - -The recovered bits are then passed through a 7-bit descrambler. If -there are no channel errors, the all 1s sequence is recovered. In the -event of a channel error, there will be a 0 in the bit stream for each -feedback tap in the descrambler. In this case, the CCSDS descrambler is -using 3 feedback taps. - -Finally, the signal is passed into a bit density measurement probe. The -channel BER is measured by dividing the 0s density by three. This -measurement is inaccurate at high BER rates (>10%) as the error 0s -begin to overlap. - -The benchmark script will, once per second, output the Costas loop -frequency offset, the recovered timing error, the estimated SNR, and the -average BER. - -NOTE: The particular SNR estimator used is inaccurate below about 7dB, -and will report erroneously high values even for random noise. - -There are a variety of Costas and M&M loop parameters one can adjust. -See ./benchmark_rx.py -h for the full set. |