[Discuss-gnuradio] Inverted spectrum
Hello all, When using pll_carriertracking_cc, the returned spectrum seems to be inverted about 0MHz, when looking though the code line 113 of gr-analog/lib/pll_carriertracking_cc_impl.cc looked odd: > optr[i] = iptr[i] * gr_complex(t_real, -t_imag); could someone explain why the the imaginary component of the NCO is inverted? Thank you all, Andrew ___ Discuss-gnuradio mailing list Discuss-gnuradio@gnu.org https://lists.gnu.org/mailman/listinfo/discuss-gnuradio
[Discuss-gnuradio] Inverted Spectrum
Hi all, currently in our reception chain we have a down converter inverting the spectrum, until now we are manualy changing the samples we get from the USRP (we use both UHD/libusrp2 API). Is there a way using the API to get the samples already conjugated ? I got a look at the UHD API and I didn't find anything suggesting this. Regards Gaetano Mendola -- cpp-today.blogspot.com ___ Discuss-gnuradio mailing list Discuss-gnuradio@gnu.org https://lists.gnu.org/mailman/listinfo/discuss-gnuradio
Re: [Discuss-gnuradio] Inverted spectrum
On Sat, Jul 13, 2013 at 8:54 PM, Andrew Davis wrote: > Hello all, > > When using pll_carriertracking_cc, the returned spectrum seems to be > inverted about 0MHz, when looking though the code line 113 of > gr-analog/lib/pll_carriertracking_cc_impl.cc looked odd: > >> optr[i] = iptr[i] * gr_complex(t_real, -t_imag); > > could someone explain why the the imaginary component of the NCO is > inverted? > > Thank you all, > Andrew Andrew, That block was written so that it would lock to a carrier at a tone that is then used to downshift the signal. So you have a signal at fc; the PLL would lock onto that and produce a tone at -fc. This is then multiplied against the original signal to shift it down to baseband directly. Tom ___ Discuss-gnuradio mailing list Discuss-gnuradio@gnu.org https://lists.gnu.org/mailman/listinfo/discuss-gnuradio
Re: [Discuss-gnuradio] Inverted Spectrum
On 10/04/2011 07:51 AM, Gaetano Mendola wrote: Hi all, currently in our reception chain we have a down converter inverting the spectrum, until now we are manualy changing the samples we get from the USRP (we use both UHD/libusrp2 API). Is there a way using the API to get the samples already conjugated ? I got a look at the UHD API and I didn't find anything suggesting this. Regards Gaetano Mendola The UHD API *is not* a signal-processing tool-kit. Its role in life is to interface software to the Ettus hardware. But Gnu Radio does have a complex-conjugate operator. -- Marcus Leech Principal Investigator Shirleys Bay Radio Astronomy Consortium http://www.sbrac.org ___ Discuss-gnuradio mailing list Discuss-gnuradio@gnu.org https://lists.gnu.org/mailman/listinfo/discuss-gnuradio
