My apologies, I am quite new to the SDR arena.
My question is the following. I want to generate an AM DSB FC (AM
double sideband full carrier) signal in baseband and then upconvert this
to a specific frequency band.
In doing so, I created a simple flowchart (.grc) file in gnuradio
companion, where I generated AM DSB FC before I sent the data to the
USRP1. I confirmed that the spectrum is correct, by viewing the
resulting spectrum on a FFT sink (in GRC). The analog signal on the
scope sink (in GRC) also displayed the correct shape. Everything was
done using the “short” data type - I didn’t use complex values.
However, after upconversion, I inspected the resulting waveform on an
analog oscilloscope, (I am using the LFTX daugterboard on a USRP1) and
the resulting waveform was not correct.
I then input a single cosine wave to the USRP1, and counter to what I
thought, the USRP1 + LFTX output AM double sideband suppressed carrier -
I was expecting single sideband modulation.
I resolved the AM modulation by inputting (1 + cos(2 pi f_m t)) to the
USRP1. But how do I generate FM then? If I generate FM in baseband, and
upconvert with the USRP1, the frequency components might not be correct,
as the upconversion do not filter the one sideband resulting from the
upconversion process out?
I have included the GRC file of how I would thought to generate AM DSB
FC, but this is clearly wrong.
Can anyone recommend good tutorials on the web on the USRP1?
Your time, effort and suggestions will be greatly appreciated