Re: [Discuss-gnuradio] The coming deluge of CPU cycles

[Eric Blossom]

On Thu, Jul 27, 2006 at 04:39:43PM +1000, Jason Hecker wrote:
> >>(http://www.plxtech.com/products/io_accelerators/PCI9030/default.htm)
> >
> >That's one route, though 32-bit 33-MHz PCI is pretty much the bottom
> >of the barrel these days.  Hence the interest in PCI-Express and/or
> >Express Card.
> 
> True.  At a glance I couldn't see any alternative from PLX for faster 
> PCI busses.  PLX's chips are fairly inexpensive though.  As an 
> alternative could you use an FPGA as the PCI-Express to USRP MkII 
> interface?

You could, but I think you burn up a pretty good chunk of a big FPGA
doing it.  There are PCI-Express to PCI-X (and/or PCI) bridge chips.
I believe this is one way (short of a custom asic) to make this all
work.  Then at least your card gets _all_ the bandwidth available from
PCI-X.  64-bit 66-MHz or 100-MHz gets pretty reasonable ;)


> >the USRP on the tower, next to the LNA and PA.
> 
> You might be able to implement power-over-ethernet to the USRP with this 
> method as well.  No need to implement 802.3af (I think that's the 
> spec.).  Even though there are no spare pairs to use for a DC feed on a 
> GigE CAT5 cable there are ethernet transformers which can isolate and 
> insert a common mode DC current onto a pair of CAT5 wires.

I think it would be hard to get enough power for the PA over the CAT5.

Eric