Re: [Discuss-gnuradio] Single-tone test using USRP2 with RFX2400 and XCVR2450

[Igor Almeida]

On Fri, Aug 28, 2009 at 5:22 PM, Eric Blossom<address@hidden> wrote:
> If you're trying to send a sine wave, this will work much better:
> (Generates a complex sinusoid == exp(jwt))
>
>  sig_source_c -> head -> usrp.sink_c
>
> Or you could use a hilbert transform to generate the quadrature
> component.  float_to_complex will be setting Q to zero the way you're
> using it.

Yes, setting Q to zero was the original idea. The whole point of using
a sine wave was to have a better estimation of when the QAM signal
actually started, but this "solution" gave me another problem to work
on :)
My question is why the received signal has sinusoidal components on
both I and Q given that the wave has been "translated" to 2.5G (upon
tx) and then back to DC (after the FPGA in rx). Should I not expect
two impulses at +- 2M? Instead, what I get is a single impulse at
aproximately -3kHz, regardless of the frequency set on the sig_source.

> Eric
>



-- 
Igor Almeida