On 03/15/2010 07:22 PM, Josh Blum wrote: > On 03/15/2010 04:09 PM, Marcus D. Leech wrote: >> Does the "tune" function actually do anything for the BASIC_RX? Does it >> just set the DDC >> appropriately? > > Tune on the basic and lf rx only sets the ddc. In other words, the IF > of the dboard is always 0 Hz in this case. > > Because this tuning relies entirely on the ddc, you are really > aliasing in frequencies above ddc_rate/2. Because of this, your RF > frontend should need a bandpass filter so only the desired range can > be aliased in. > > The tune method should do the right thing. Well, the front-end converts everything to complex baseband, so in this case, do I just hand "tune" the offset frequency? That is, does it "deal" with negative frequencies?
We'll go back to the example. Complex quadrature direct-conversion receiver, giving "I" and "Q" from DC-4MHz to DC+4MHz. That is, it converts everything to baseband. Do I tune frequencies below DC, using negative values to the tune function? I know this seems rather rudimentary, but please have patience for me :-) -- Principal Investigator Shirleys Bay Radio Astronomy Consortium http://www.sbrac.org _______________________________________________ Discuss-gnuradio mailing list [email protected] http://lists.gnu.org/mailman/listinfo/discuss-gnuradio
