What does the "corresponds to DC in the IF"mean?

GNU Radio
1

hi all:
I recently see the “corresponds to DC in the IF” in the function
set_freq() of the db_basic.cc.so what does this sentence mean? In other
word, I want to know what is the function of the parameter baseband_freq
in the set_freq().I hope someone can help me the figure it out.

                                                                                                                                                                           Thank

you in advance

2

2010/8/5 intermilan [email protected]:

hi all:
I recently see the “corresponds to DC in the IF” in the function
set_freq() of the db_basic.cc.so what does this sentence mean? In other
word, I want to know what is the function of the parameter baseband_freq in
the set_freq().I hope someone can help me the figure it out.

0 (DC) in gunradio is moved up to whatever center frequency you
specify in set_freq in the RF circuitry.

3

Thanks for the answer.

Is that mean if I set the center frequency at 2.5G(RFX2400),the DC is
also at 2.5G?or other values?

                                                                                                  Thank

you

4

On 08/06/2010 12:57 AM, intermilan wrote:

Thanks for the answer.

Is that mean if I set the center frequency at 2.5G(RFX2400),the DC is also at 2.5G?or other values?

Maybe

Due to hardware limitations, the daughterboard may not always achieve
the desired center frequency, and will therefore leave you with a small
offset. The FPGA dsp can account for this additional offset by shifting
your signal to achieve sub-Hz resolution. In addition, you can shift
your signal again in the host :slight_smile:

Sometimes, you intentionally force the daughterboard to have a large
offset to move the LO out of the band of interest.

-Josh