[Discuss-gnuradio] Re: Low-cost hardware options

[Patrick Strasser]

schrieb Marcus D. Leech on 2011-01-15 03:10:
> I've posted my latest thoughts at:
> 
> http://www.sbrac.org/files/digital_receiver2.pdf

I like the design. With an USB2.0 interface it comes close to the
FuncubeDongle.

> This version has some BOM cost estimates for most of the items, and
> shows a new PLL, the ADF4351, which is a new chip from AD, coming out later 
> this spring, which is pin compatible with the ADF4350, and includes a lower 
> minimum output frequency, which means extending the range downwards to about 
> 18MHz from about 68MHz.
> Cool.
> 
> Going to a AD6652 (which has built-in DDC and CIC decimators) increases the 
> price of the ADC by a factor of 3, but it would eliminate the need for a FPGA 
> on the "host interface" side of that FMC connector.  So, you're trading a 
> more expensive digital-receiver section for a cheaper "host interface" 
> section.  For example, by using an AD6652, one could easily conceive of 
> nothing more than a cheap EZ-FX2 USB-2.0  implementation on the 
> host-interface side.
> 
> For at least USB-3.0 and 1GiGe, you pretty-much *need* an FPGA on the
> host-interface board to do all the relevant protocol goop anyway, so perhaps 
> making that FPGA large enough to do DDC and CIC decimation as well as the 
> "host interface goop" is the right trade-off.

You have no host interface. Adding a host interface without FPGA results
in the the need for hardware DDC/CIC. An FPGA would add in cost and
complexity.

One of the Digilent parts could be a starting host interface. A second
step could be designing a OS host interface with FPGA, something could
imagine quite a lot of people could find interesting. Maybe there are
existing designs.

Patrick
-- 
Engineers motto: cheap, good, fast: choose any two
Patrick Strasser <patrick dot strasser at  tugraz dot at>
Student of Telematik, Techn. University Graz, Austria