[Discuss-gnuradio] beginner question, changing phase

[Colopy, Robyn]

Hi, I'm new to gnuradio, could you guys help me out? I want to change the phase 
of a sine wave at set intervals.

One method I have tried is creating a vector of alternating 1's and -1's and 
multiplying it by a sine wave to cause a 180 degree phase shift, as shown 
below. This works, however I have not been able to determine how long the 
vector must be to correspond predictably to the wave.

            bpsk_data = (1, 1, -1)
            bpsk_stream = gr.vector_source_c(bpsk_data, True)
            multiplier = gr.multiply_cc()
            self.connect(self.siggen,(multiplier,0))
            self.connect(bpsk_stream,(multiplier,1))
            self.connect(multiplier,self.u)

I have also tried to use the NCO function described here: 
http://www.nd.edu/~jnl/sdr/docs/tutorials/9.html#tth_sEc8.2 but I can't find 
any documentation on how to call it. I've tried a couple variations and keep 
getting the error " 'module' object has no attribute 'fxpt_nco' ".

If anyone has any insight on how to map a vector to a wave, or how to use the 
fxpt_nco block, I'd really appreciate it.

Thanks!

Robyn Colopy