Re: Frequency Xlating Fir Filter issue passing message

On 03/20/2020 05:10 PM, Vitt Benv wrote:

Good evening,

I'm trying to make a multimode receiver using a PlutoSDR; all the demodulation and visualization parts work correctly.  Now I would like to use a click'n-point tuning and as a result I have tried to understand something more about the use of controlports.  I followed some tutorials and made a custom block (myblock.py "Message splitter") which receives the message generated by double clicking on the waterfallas an input and  generates a message to be sent to the Frequency Xlating Fir Filter block, which consists of an offset between the center frequency (fx) and the frequency generated by the double click.  I state that by controlling this block with a slider (fx_tune) everything works correctly, but using the outgoing message the set frequency is completely incorrect.  In the embedeed block I perform an output of the variables involved directly on the console and everything "apparently" is correct.  Any ideas / suggestions?  Attached is the .grc file, the source of the "Message splitter" block and a printscreen of the blocks (I have eliminated what is unnecessary and already functional).  Thanks in advance,    Vittorio, I3VFJ

Quick look suggests that you're confused about how the freq-xlating-filter works.  The center frequency is the *baseband* frequency, not
  the RF frequency that your hardware is tuned to.  Gnu Radio, internally, deals with basebanded signals, typically, and the RF frequencies
  are purely hardware-on-the-outside thing.