Dear All: I have some questions regarding BasicTX Daughterboard. It seems that this board does not have complex design such as analog mixer. But it can be set with a carrier frequency in GNU Radio. My questions are: 1) When I use this daughterboard and set its carrier frequency to nonzero (e.g., 50 MHz), is the frequency up-conversion done in the digital domain by the motherboard's FPGA? 2) If I use this daughterboard in IQ mode (i.e., setting frontend to AB), what are the output signal at antenna ports Tx-A and Tx-B? Denote S(t) as the digital baseband signal and fc as the carrier frequency specified in GNU Radio, are the output signals at Tx-A and Tx-B ports Re{S(t)}*cos(2*pi*fc*t) and Im{S(t)}*sin(2*pi*fc*t), respectively? If not, what is the output signals at those two antenna ports? Thank you in advance! Hua

Hua, Yes to both questions. If you drive a constant DC amplitude into a USRP sink in GR then you can observe the frequency and phase of the FPGA “digital LO” on an oscilloscope easily. -ian > On Nov 16, 2018, at 9:40 PM, Huacheng Zeng via USRP-users <usrp-users@lists.ettus.com> wrote: > > Dear All: > > I have some questions regarding BasicTX Daughterboard. It seems that this board does not have complex design such as analog mixer. But it can be set with a carrier frequency in GNU Radio. My questions are: > > 1) When I use this daughterboard and set its carrier frequency to nonzero (e.g., 50 MHz), is the frequency up-conversion done in the digital domain by the motherboard's FPGA? > > 2) If I use this daughterboard in IQ mode (i.e., setting frontend to AB), what are the output signal at antenna ports Tx-A and Tx-B? Denote S(t) as the digital baseband signal and fc as the carrier frequency specified in GNU Radio, are the output signals at Tx-A and Tx-B ports Re{S(t)}*cos(2*pi*fc*t) and Im{S(t)}*sin(2*pi*fc*t), respectively? If not, what is the output signals at those two antenna ports? > > Thank you in advance! > > Hua > > > > > > _______________________________________________ > USRP-users mailing list > USRP-users@lists.ettus.com > http://lists.ettus.com/mailman/listinfo/usrp-users_lists.ettus.com