[Discuss-gnuradio] Direct conversion receiver

[John Andrews]

Hi,

If the signal transmitted at the transmitter is represented as, 

x(t) = X_i(t)cos(2*pi*fc*t) - X_q(t)sin(2*pi*fc*t), where X_i(t) and X_q(t) are inphase and quadrature components of the message signal.

then, at the receiver does the following equation correctly represent the signal after downcoversion to baseband like in a "RFX2400 + USRP' set up.

inphase component of received signal = X_i(t)cos(2*pi*f_offset*t + phi )  + noise_component

quadrature component of received signal = X_q(t)sin(2*pi*f_offset*t + phi) + noise_component

where, 'f_offset' is the frequency offset present and 'phi' is the received signal phase.

Can someone suggest a good reference to direct conversion receivers?

Thanks.