[Discuss-gnuradio] Re: Low cost hardware option

[Patrick Strasser]

schrieb Marcus D. Leech on 2011-01-13 04:56:
> On 01/12/2011 10:46 PM, Brian Padalino wrote:

> I'm increasingly liking the approach where you "demarc" at the digital
> output of the ADC that I suggested
>   earlier where you terminate in something like a LPC-FMC connector or
> something equally
>   convenient, which allows you to adapt to various "getting bits to the
> host" approaches.
>  Including:
> 
>      o 1GiGe
>      o USB-2.0
>      o USB-3.0
>      o PCIe
 o direct (embedded)
Any chance to transfer via eSATA? Quite common nowadays.

> But maybe that's the road to *more* expensive, not less (although cost
> is only ONE of the factors
>   of a project like this).

First, price is one constraint, or one of the features, that would make
such a device attractive to a wide audience. Others would be
flexibility, simpleness, that is fitness for home building,
capabilities: lowest/highest frequency, dynamic range, simultaneous
bandwidth, DDC, filtering, FPGA; RX only vs.s RX and TX; interface and
others.

For price: I'd say 200$-300$ for a tunable frontend, 16bit resolution,
>500kSps and flexibility to support IF input, clock input, digital
stream output (for other transport/consuming system) DIY-kit is
attractive. If the flexibility is not available, this would be to
expensive. Phillip Balister tried to connect a USRP to a Beagle Board,
which was not so easy because the USRP hat no way to tap the data
between the FPGA and the USB interface.

For flexibility, being able to bypass stages or feed signals e.g. at the
ADC would be cheap. Preparing for different transport systems would make
it more future proof. If USB3.0 hardware support is not satisfying now,
maybe it is in two years. For the data bus part this would require a
prepared interface for data and control lines.

I see the target for such at above all the soundcard solutions and below
the USRP1. USRP1 can do 8MHz Bandwidth complex at 14bit/sample RX, which
is more than enough for hobbyists. What would be interesting for
university teaching and research? What would be interesting for other
potential users, like hams? Did I miss some?

USB3.0 is common at new high end PCs and Laptops, ExressCard at Laptops.
Of course every PC with PCIe is ubgradable to both of them, but it's
extra money to spend and extra hassle to get it started. I do not see
urgent need for such extreme data rates. This could be a second step.

For a start, a not too expensive, but still capable system with options
for extension seems most doable for me. If the transport systems is to
be fully integrated in the first shot, at least the data should be
accessible via some interface.

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