Re: [Discuss-gnuradio] Re: A Humble Request.... - "Open-Hardware"

[Moeller]

On 10.01.2011 02:22, Marcus D. Leech wrote:
> The SSRP, as far as I can tell, is dead. Last status update was nearly 4 
> years ago.

The development stopped apparently. But at least he has a working design for 
the RX part.

> o The ADC board (single-channel, thus cannot handle direct-conversion with I 
> and Q sampling) $120.00
> o Uses an Off-The-Shelf ElraSoft FX2 board, which in 2007, sold for $89.00

Oh, forgot about the USB interface, so it's about $200. That would be my limit 
for a home-product.

>
> But it won't do complex sampling, and it won't do DDC and decimation, so your 
> host computer had better be prepared to receive
> 25Msps and "do stuff with it".

Depends what you want to do with it. For waterfall, spectrum-, logic- and 
signal analysis you don't need complex sampling, IF will do it. It's just a
shift on the frequency axis. Ok, need double sample number, but real-to-complex 
FFT is faster. Not much difference.
My interest is just to have some hobby box that can do more than my old analog 
oscilloscope. It's also for the kids to do some electronics education.
They need a bit more than just a few blinking LED. >$1000 for USRP is a bit too 
expensive for an electronics toy.

> That's $511.00, and we still don't have DDC or decimation, since we don't 
> have an FPGA, and that poor little FX2 isn't going to be

But that's a different design. It can be cheaper. For the material cost, the 
USRP is about $200, somebody reported on the list.
It doesn't have to be a SSRP, but I would like to buy or built something in the 
€200 range.

> Ok, so maybe we can run the ADCs and DACs at a lower rate, so that we can do 
> the DDC and decimation in the FX2? I'd be
> *astonished* if it could keep up with input rates beyond roughly about 
> 200Ksps complex, which is cheap sound-card territory. Oh dear.

Not if a modern PC with appropriate programming (SSE extensions) would do the 
decimation.