Hi Khalid,
the VCO is phase-continous, so the starting phase of your sweep should
be continous with the end phase of your last sweep.
The block does not offer a way to reset its phase; out of the top of my
head there's also no easy "workaround" for this, only rather complex
solutions like constantly calculating the argument of the vco output,
sample_and_hold that argument on the sawtooth minimum, and dividing the
VCO output by the output of phase_modulator with the sampled value as
input (which should shift everything by the -phase(t=t_sawtooth_minimum) ).
I think it might be easier for you to just copy the functionality of
vco_fc, but that would require programming a block in C++ or python
(preferably C++, because you could just copy&paste 90% of the
functionality from the original vco_fc.h, vco_fc_impl.{cc,h}), and I
don't know if that suits your level of GNU Radio knowledge.
With best regards,
Marcus Müller
On 10.07.2014 19:27, khalid.el-darymli wrote:
> Hi,
>
> I am using the VCO block in GRC to generate complex-valued sweeps with BW
> of 50 KHz and a sweep time of 1 second. The VCO is driven by the sawtooth
> signal generator in GRC.
>
> The problem I am facing is that subsequent sweeps do not start at the same
> time. Each new sweep seems to have a random phase shift relevant to the
> other. Please see the attached figure which demonstrates the case for seven
> subsequent sweeps. This figure was generated in Matlab after saving the
> output of VCO to a binary file in GRC. Then, for the sampling frequency of
> 50 KHz, individual sweeps were resolved and superimposed on each other.
>
> My question is, how do I reset the phase of the VCO at the beginning of
> each new sweep?
>
> Thank you.
>
> Best regards,
> Khalid
>
>
>
> _______________________________________________
> Discuss-gnuradio mailing list
> Discuss-gnuradio@gnu.org
> https://lists.gnu.org/mailman/listinfo/discuss-gnuradio
_______________________________________________
Discuss-gnuradio mailing list
Discuss-gnuradio@gnu.org
https://lists.gnu.org/mailman/listinfo/discuss-gnuradio
