Hi all, I am currently trying to get plot the received bpsk samples and look at the constellations as received by the USRP, but all I get a big 'ole blob of points in the middle.
I think the main issue probably has to do with the interpolation and decimation rates so I included that code at the bottom, the whole source is attached along with a symbol plot. I In the symbol plot you can clearly see the received bits on the 'unit' circle, I was wondering why there are so many bits clustered at the crossing point; I was expecting a big clump above/below 0 (which I have) and almost no points at 0. My questions are: 1. Is this the right way to find the decimation and interpolation rates for a given bit rate (I tried to base it off of pick_bitrate.py) 2. Using only one USRP, will there be significant (any?) constellation rotation? 3. Why are there so many ambiguous bits (maybe same as #1) data_rate = 250000 bits_per_symbol = 1 # 1:bpsk 2:qpsk 3:8psk, etc #Calculated generic parameters bit_rate = 8 * data_rate symbol_rate = bit_rate / bits_per_symbol arity = pow(2,bits_per_symbol) #User defined transmit parameters tx_samples_per_symbol = 1 tx_converter_rate = 128e6 #Default DA converter rate tx_interp_rate = int(math.ceil( tx_converter_rate / tx_samples_per_symbol / symbol_rate )) rx_samples_per_symbol = 1 #How many rx samples are devoted to one symbol? rx_converter_rate = 64e6 #Default AD converter rate rx_decim_rate = int(math.ceil( rx_converter_rate / rx_samples_per_symbol / symbol_rate ))
capture_bpsk_symbols.py
Description: Binary data
<<attachment: bpsk_constellation.jpg>>
_______________________________________________ Discuss-gnuradio mailing list Discuss-gnuradio@gnu.org http://lists.gnu.org/mailman/listinfo/discuss-gnuradio