Re: [Discuss-gnuradio] sending single tone Am modulated using usrp1+wbx

[Marcus D. Leech]

Marcus thanks for your help.

I was trying with 2 antennas (WA5VJB) varying the usrp tx gain but the results are the same (In this moment I don’t have an attenuator). I was reading a past mail from this list (March 25 2012) and there is a similar problem that I have: the q component is not zero, I send a mail to the list asking for it…. 

thanks

Consider the attached AM transmitter simulation that uses a complex signal source for both the modulation source (1kHz tone), and the carrier (0Hz).

Note that the signal spectrum is exactly as you would expect, and I and Q are *both* non-zero in the "scope" sink.

Keep in mind that the representation of signals we talk about here is given by:

x(t) = x1 (t) cos(ω0 t) − x2 (t) sin(ω0 t)


And that direct-conversion SDR hardware (such as the USRP) uses the I/Q representation of the signals, in which both the in-phase and quadrature
  components are significant.

-- 
Marcus Leech
Principal Investigator
Shirleys Bay Radio Astronomy Consortium
http://www.sbrac.org

complex_am_xmit.grc
Description: application/gnuradio-grc