On Mon, Sep 5, 2011 at 12:55 PM, John Ackermann N8UR <[email protected]> wrote:
> Hi Marcus -- > > I am selecting complex taps from the drop down, but still get an error at > runtime if either cutoff frequency is 0 or smaller. > > Thanks, > > John > ---- John, That sounds like a bug in the GRC block, then. I just tried this as a complex BPF and it works fine: gr.firdes.complex_band_pass(1, 1, -0.1, 0.2, 0.1) However, as was already mentioned, if you are trying to create a bandpass filter from -40 to +40 kHz, that's just a low pass filter with a bandwidth of 40 kHz: gr.firdes.low_pass(1, 100e3, 40e3, 2e3) Will give you a filter for this purpose. Substitute your own sampling rate and transition width, of course. Tom > On Sep 5, 2011, at 11:46 AM, "Marcus D. Leech" <[email protected]> wrote: > > > On 05/09/11 10:19 AM, John Ackermann N8UR wrote: > >> I'm generating two NBFM signals, offsetting them plus and minus 25 kHz > >> with FreqXlatingFilters, and combining the output in an adder which > >> then drives a USRP sink. It seems sensible to put a bandpass filter > >> on the result. > >> > >> I have a basic conceptual confusion. I would think that you'd specify > >> a bandpass filter around zero with a low cutoff of, say, -40e3 and a > >> high cutoff of +40e3. However, this doesn't work -- the bandpass > >> filter seems to require a number >0 for the lowpass frequency. > > Make sure that you specify complex-taps. I assume you're using GRC. By > > default, it uses the version of > > the bandpass filter with real taps. But if you specify complex taps, > > you can use negative frequencies. > > > > > > -- > > Principal Investigator > > Shirleys Bay Radio Astronomy Consortium > > http://www.sbrac.org > > > > > > > > _______________________________________________ > > Discuss-gnuradio mailing list > > [email protected] > > https://lists.gnu.org/mailman/listinfo/discuss-gnuradio > > _______________________________________________ > Discuss-gnuradio mailing list > [email protected] > https://lists.gnu.org/mailman/listinfo/discuss-gnuradio >
_______________________________________________ Discuss-gnuradio mailing list [email protected] https://lists.gnu.org/mailman/listinfo/discuss-gnuradio
