[Discuss-gnuradio] question about USRP up/downconversion

[Songsong Gee]

I have some curiosity about USRP up/downconversion

If I have a rectangular pulse train

and I want to send it with carrier freq. 2.4G

So I set frequency in USRP block with freq. 2.4G

Then, my rectangular pulse train is moved to 2.4G band in frequency domain?

In other words, USRP block automatically moves baseband signal to carrier frequency? And is it called 'upconversion' ?

Or, before the USRP block, do I have to multiply a sinusoidal signal with freq. 2.4G ?

In advance, If I have a signal with two main component with freq. 100M and 200M

and USRP carrier freq. is 2.4G,

Then does this performs FM with freq. 2.5G and 2.6G?

I have some difficulties about understanding modulation and carrier frequency