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

[Igor Almeida]

On Fri, Apr 24, 2009 at 12:30 AM, Yongsang Kim<address@hidden> wrote:
> Hi, all.
>
> I did single-tone test using USRP2 with RFX2400 and XCVR2450.
> There are some undesired signals in the results.
>
> My single-tone test is as follows:
> - Wired connection between USRP2 and Spectrum analyzer
> - Single-tone is transmitted from USRP2 using the following commands
>   ./usrp2_siggen.py -f xxxx
>   ./usrp2_siggen.py -f xxxx -w xxxx
> - For daughter board, RFX2400, XCVR2450 and Basic TX are tested
> - Newest GNU radio and firmware

I [believe I] am having a similar problem with USRP rev4 and RFX2400.
Sending a QAM-modulated signal in a 2.5GHz carrier with no
synchronization gives me a lot of background noise before the actual
signal. So I am prepending a 2MHz sine wave in a separate block,
executed prior to the QAM modulation, but I cannot find the impulses
in +- 2M after the receiving USRP downconverts it from 2.5GHz.
The part of the signal which is supposed to contain the 2M wave shows
both real and imaginary sinusoidal signals, always close to DC by 3k
Hz or so. Am I missing anything?

-- 
Igor Almeida