Re: [Discuss-gnuradio] Transmit filtering

[John Ackermann N8UR]

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
----

On Sep 5, 2011, at 11:46 AM, "Marcus D. Leech" <address@hidden> 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
> 
> 
> 
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