[Discuss-gnuradio] Understand AM signal reception -- No Q component ??
From:
senthil murugan
Subject:
[Discuss-gnuradio] Understand AM signal reception -- No Q component ??
Date:
Sun, 25 Mar 2012 11:11:02 +0530
Hi all,
I have some doubt in understanding working principle of usrp. I just want to confirm my understanding:
1. I have AM modulated singnal x(t)cos(2*pi*fc*t) and i am receiving that signal in antenna.
2. In Daughter board, this signal is multiplied by cos(2*pi*fc*t) and
sin(2*pi*fc*t) in two separate branches (assuming Direct conversion --
Baseband conversion)
4. Branch 2: x(t)cos(2*pi*fc*t) * sin(2*pi*fc*t) --> LPF --> 0 (since cos and sin are orthogonal) --> FPGA
5. Since Daughter board is doing direct conversion, no mixing in FPGA (i.e) in DDC.
6. In PC, I will have I component as x(t) and Q component as 0 for AM modulated signal.
Is my understanding correct?
Similarly if I take OFDM modulated signal -- xr(t)cos(2*pi*fc*t) -
xi(t)sin(2*pi*fc*t) -- output at Daughter board will be xr(t) at I
component and xi(t) at Q component. This will be send to PC. Is it
correct?