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Re: [Discuss-gnuradio] USRP2 Announcement

From: Eric Cottrell
Subject: Re: [Discuss-gnuradio] USRP2 Announcement
Date: Fri, 12 Sep 2008 16:04:27 -0400 (EDT)

----- Start Original Message -----
Sent: Fri, 12 Sep 2008 12:04:44 -0700
From: Eric Blossom <address@hidden>
To: Douglas Geiger <address@hidden>
Subject: Re: [Discuss-gnuradio] USRP2 Announcement

> On Fri, Sep 12, 2008 at 01:54:08PM -0500, Douglas Geiger wrote:
> > Very exciting!
> >
> > One technical question:
> > By 25 MHz of instantaneous RF bandwidth - do you mean the 100Msamples/s 
> > from the ADC gets decimated down to 50Msamples/s?  In which case, is the 
> > Gig-E able to handle that much sustained throughput (I'm guessing that's 
> > with 8-bit samples?).
> 100MS/s I & Q is decimated to 25MS/s complex.  We use 16-bit I & Q.
> That works out to ~800Mbit/s on the gigabit ethernet,  which the USRP2
> can sustain, no problem.  
> > Also, does the locking of the clocks of multiple USRP2's work like the 
> > USRP, e.g. where I can set one as the master and the other as slave - i.e. 
> > is the MIMO cable you refer to a coax SMA-SMA cable to connect the clock 
> > in/out connect (which have to be soldered in place) and the 2-wire cable to 
> > the daughterboard (like described on 
> > http://gnuradio.org/trac/wiki/MultiUsrp)?
> No soldering required.  The mimo cable is a serial attached scsi cable
> repurposed for our needs.  The host configures the clocking on the
> USRP2s over the ethernet.
> Here are the clocking options:
>   USRP uses it's own free running xtal oscillator
>   USRP uses the external reference input (SMA connector)
>   USRP uses the clock provided over the MIMO cable.
> In addition, the master is programmed to drive clock onto the 
> MIMO cable.
> Eric
> _______________________________________________
> Discuss-gnuradio mailing list
> address@hidden
> http://lists.gnu.org/mailman/listinfo/discuss-gnuradio

----- End Original Message -----

Is 14 bits good enough to do HF receive without doing special gain control or 

I assume that I could take the whole HF spectrum, output it at 15 MSPS, and 
only need 480Mbit/s of ethernet bandwidth and 60 MBytes of disk space per 
second of recording.  I could put about 1-1/2 minutes of HF spectrum on a 
single layer DVD-R.  I guess I need that Blu-Ray drive now.

I ordered one today and I hope I get it before I leave for the DCC.  The case 
alone looks neat.

73 Eric

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