Hi all,

I am working with a usrp2+BasicRx and an external tuner with a 21.4 MHz

IF

output and a bandwidth of about 20 MHz.

The same setup but with usrp1 (instead of usrp2) it’s working well.

Now I am injecting a tone at 21.45 MHz (-60 dBm) at the input of the

BasicRX

and set the usrp2 freq at 21.4MHz (with “set_rx_freq()” UHD API).

The problem is that:

a) with sample rate > of about 3.125M I have 2 strong spuriouses. The

first

in the middle of the FFT (FFTDIM/2) and the second one at about the

middle

of the second half of the FFT

b) with a sample rate <=3.125 the second spurious disappear but the

first at

FFTDIM/2 is still present.

In both case I can also see the tone at 21.45MHz.

To compute the spectrum I use matlab

[10*log10(|fftshift(fft(signal*window))|^2)].

Am I doing mistakes or someone have the same problem ?

Suggestions ?

Thanks in advance

Luca