Histogram
Probably the easist way is to recompile the FPGA with the mode register set to 1. This will output the raw channel 1 I ADC samples over ethernet.
Change the line 149 in cpu.v to out_port_47 <= 1;
Capture the data from the ethernet port by using the command:
sudo gulp -i enp2s0 -f "ether host 00:01:02:03:04:09" > ch1.pcap
Gulp's buffer doesn't have to be set as you only need 4 or 5 seconds of data.
The packet2ch_stream program strips the PCAP file format and dumps out a raw stream of data.
<ch1.pcap ../fpga/GNSS_Firehose-alan/test/packet2stream > ch1.stream
This can then be processed by GNU radio.
The flow graph used is shown below:
Not much too it, the a file source takes in 2's compliment bytes, converts them to floats and then displays a histogram and an FFT. The results are below:
