[USRP-users] Question on max. baseband bandwidth: can we go above 120 MHz on the TX side?

Ruben.Merz at swisscom.com Ruben.Merz at swisscom.com
Tue Sep 23 14:41:26 EDT 2014


Marcus,
Thanks for the comments. Indeed, if it were only wide-band noise, we could go with dedicated hardware. But, and I should have expressed myself better, we want to generate different type of noise and perturbations on a wide range of bandwidth and of center frequencies (typically from above DC to several 100 MHz). Intended application is testing of G.fast modems.
Ruben  

> -----Original Message-----
> From: USRP-users [mailto:usrp-users-bounces at lists.ettus.com] On Behalf Of
> Marcus D. Leech via USRP-users
> Sent: Tuesday, September 23, 2014 7:06 PM
> To: usrp-users at lists.ettus.com
> Subject: Re: [USRP-users] Question on max. baseband bandwidth: can we go
> above 120 MHz on the TX side?
> 
> On 09/23/2014 12:50 PM, Ruben Merz via USRP-users wrote:
> > Hi list,
> >
> > We were discussing with some colleagues today whether to use a USRP
> (x300 specifically) to generate wideband noise with a basicTX for testing
> purpose. According to the data-sheet, the x300 can do 120 MHz of RF
> bandwidth from the host. But when I look into
> http://www.trondeau.com/storage/grcon14/presentations/Sep16_05_Ettus_
> Updates.pdf, I see 300+ MHz on slide 9. And if I look further in the spec, the
> DAC can go up to 800 MS/s.
> >
> > Therefore my question: if we were to generate signals directly from the
> FPGA; would it be feasible to generate 400 MHz wide signals (I understand
> that the basicTX is limited to 250 MHz though)? Where would be the
> limitation?
> >
> > Thanks for any comment
> > Ruben
> > _______________________________________________
> > USRP-users mailing list
> > USRP-users at lists.ettus.com
> > http://lists.ettus.com/mailman/listinfo/usrp-users_lists.ettus.com
> >
> I think the bus interface on the DAC is limited to 400Msps.
> 
> But if you just want to generate broad-band noise, where the shape doesn't
> matter that much, consider a zener diode + amplifier + filter.
> I don't know
>    anything about your application.  But if I had the problem of "I need to
> produce broad-band RF noise for testing things", I'd probably consider
>    a hardware-based approach first.
> 
> 
> 
> --
> Marcus Leech
> Principal Investigator
> Shirleys Bay Radio Astronomy Consortium
> http://www.sbrac.org
> 
> 
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