At 20.51 22/10/2009, you wrote: > > >my question was why the flex-radio system is offset from the lo by 11Khz. >if there is clock jitter in the sampling system that same jitter >would also be present at the offset.
Guido, build a SoftRock and see :-) There is a lot of noise around zero, due to 1/F noise, DC residual, hum etc. 11 kHz is just at the center of a standard audio card sampling at 22050 Hz, giving 10 kHz per side with relatively low spurious content. So, a good compromise. But I'm not jocking, let build a SoftRock or borrow one, and see what's out of the sampler with no input, when listening with a Realtek sound interface and an high-quality one. You will be impressed, the problem driving the 11 kHz choice is not (all) in the QSD. 73 - Marco IK1ODO
