Re: [Discuss-gnuradio] pll refout vs carriertracking

[Robert McGwier]

You are correct.  pll_carriertracking_cc returns the recovered carrier.  
Sending to baseband is then done by a complex multiply block, don't 
forget the conjugation.


Bob


Charles Swiger wrote:
> All - Do I understand correctly that gr.pll_carriertracking_cc() is
> supposed to downconvert to DC?  I don't see it doing that, and can't
> see in the work functions where that magic would be accomplished.
>
> Just want to make sure I'm building the most efficient graph possible.
> I tried both in an existing AM detector with a 7.5KHz IF and both work
> just the same with an external mixer. 
>
>
> ----------------------------------------------------------------
> refout:
>
> int
> gr_pll_refout_cc::work (int noutput_items,
>                    gr_vector_const_void_star &input_items,
>                    gr_vector_void_star &output_items)
> {
>   const gr_complex *iptr = (gr_complex *) input_items[0];
>   gr_complex *optr = (gr_complex *) output_items[0];
>
>   float error;
>   float t_imag, t_real;
>   int   size = noutput_items;
>
>   while (size-- > 0) {
>     error = phase_detector(*iptr++,d_phase);
>
>     d_freq = d_freq + d_beta * error;
>     d_phase = mod_2pi(d_phase + d_freq + d_alpha * error);
>
>     if (d_freq > d_max_freq)
>       d_freq = d_max_freq;
>     else if (d_freq < d_min_freq)
>       d_freq = d_min_freq;
>     gr_sincosf(d_phase,&t_imag,&t_real);
>     *optr++ = gr_complex(t_real,t_imag);
>   }
>   return noutput_items;
> }
>
>
> -----------------------------------------------------------------
> carriertracking:
>
> int
> gr_pll_carriertracking_cc::work (int noutput_items,
>                                  gr_vector_const_void_star &input_items,
>                                  gr_vector_void_star &output_items)
> {
>   const gr_complex *iptr = (gr_complex *) input_items[0];
>   gr_complex *optr = (gr_complex *) output_items[0];
>
>   float error;
>   float t_imag, t_real;
>
>   for (int i = 0; i < noutput_items; i++){
>     error = phase_detector(iptr[i],d_phase);
>
>     d_freq = d_freq + d_beta * error;
>     d_phase = mod_2pi(d_phase + d_freq + d_alpha * error);
>
>     if (d_freq > d_max_freq)
>       d_freq = d_max_freq;
>     else if (d_freq < d_min_freq)
>       d_freq = d_min_freq;
>     gr_sincosf(d_phase,&t_imag,&t_real);
>     optr[i] = gr_complex(t_real,t_imag);
>     d_locksig = d_locksig * (1.0 - d_alpha) + d_alpha*(iptr[i].real() *
> t_real + iptr[i].imag() * t_imag);
>
>     if ((d_squelch_enable) && !lock_detector())
>       optr[i] = 0;
>   }
>   return noutput_items;
> }
>
>
>
>
> _______________________________________________
> Discuss-gnuradio mailing list
> address@hidden
> http://lists.gnu.org/mailman/listinfo/discuss-gnuradio
>
>   


--
AMSAT VP Engineering. Member: ARRL, AMSAT-DL, TAPR, Packrats,
NJQRP/AMQRP, QRP ARCI, QCWA, FRC. ARRL SDR Wrk Grp Chairman
"An expert is a man who has made all the mistakes which can be
made in a very narrow field."  Niels Bohr