[Discuss-gnuradio] BPSK transmitter - time domain waveform

[senthil murugan]

Hi all,

I have some doubt on the time domain view of bpsk signal generated in Gnuradio and usrp. I used psk mod block in GRC (sps =2) and created bpsk (baseband )waveform with vector source producing 0,1,1 continuously.

When I plotted the output of psk mod block using scope sink, I seen waveform of  constant 1 for some samples (for 0) , inverted root-raised cosine waveform (for 1) and another inverted root-raised cosine waveform (for 1). This is repeated continuously and i understand that it because of transmit pulse shaping.

Now, the question is when I give this signal to USRP for transmission, how the time-domain view of that waveform look like?  Will it look like sinusoid signal with 180deg phase shift as we all seen in stand. communication text books? I guess it will not the case. I tried  multiplying  the baseband waveform with signal source (complex) -- mathematical equivalent of what happening in usrp -- and seen waveform. No smooth shift of 180deg. 

If anyone having usrp and digital oscilloscope, could you please send me the pic of time domain view of output of usrp? 

Thanks

Senthil