On 08/17/2012 05:09 AM, Sanat Gulvadi wrote:
> Greetings,
>
> How are the effects of DC mitigated in GNU radio? For example, if I use the
> uhd_fft.py to just scan the spectrum, I do not see any DC spike at the
> centre frequency. When I looked at the code, it has :
>
> r = self.u.set_center_freq(target_freq, 0)
>
> So I assume, it does not use the advanced tuning feature of UHD. Is this
> correct? How, in this case is there no DC spike seen at the centre
> frequency?
> I am trying to code a scanning system that goes through the whole frequency
> band of my RFX2400 dboard and at each center frequency, I grab a packet
> from the air and apply an FFT to check for possible interferers etc. But I
> am ending up with a spike at every centre frequency iteration. I have used
> the two stage advanced tuning to try and push the DC leakage out of my band
> of interest but I see no difference. I still get that single spike. (I am
> using the UHD library and not GNU Radio)
>
There is a DC removal in the USRP, but it needs some time to integrate.