Fast / medium fast : AtoD & DtoA

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Fast / medium fast : AtoD & DtoA

Postby Dr.BeauWebber » Tue Dec 18, 2012 3:54 pm

So the first thing that software radio and the like need is the Analogue to Digital and Digital to Analogue I/O.

I believe the available I/O pins on this system indicate that this I/O should go via the Xilinx FPGA on the Linux host board.
Does anyone have plans to either mate existing I/O hardware to this FPGA, or lay-out a new set of board/boards ?

My feelings are that we will need both a high-speed (say ~100MS.s-1 12 bit) version and a more modest serial I/O (say 1 MS.s-1 with possibly higher precision) version.
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Re: Fast / medium fast : AtoD & DtoA

Postby theover » Wed Dec 19, 2012 3:04 pm

Make it competative: there are great AD/DAs available from TI and Analog and probably others, which push the performance boundaries instead of becoming an average "raspberry for $25" approach. On the other hand, making a PCB with good converters needs to get paid..
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Re: Fast / medium fast : AtoD & DtoA

Postby aolofsson » Wed Dec 19, 2012 3:52 pm

Thanks for the post!

Here is a high level blog post we wrote some time back about SDR and the Parallella platform:
http://www.adapteva.com/white-papers/sd ... arallella/

We will start prototyping SDR concepts in the near future with a dual site FMC card board, Zynz702:
http://www.analog.com/static/imported-f ... _FPGAs.pdf

The idea is to eventually shrink the whole prototype system down to a two credit card stacked board solution. Hopefully something will be up and running by the end of May.

With the 1GB/s bandwidth into the Parallella board from the GPIO connectors, it should be possible to make some very powerful systems. Heterogeneous computing is a big win here with three different powerful processing solutions (FPGA, ARM, and Epiphany) each focused on it's area of excellence. We owe everyone the specs for the daughter card format (still working out the exact pinout..)! As soon things stabilize will start collaborating with groups on an SDR specific daughter card.
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Re: Fast / medium fast : AtoD & DtoA

Postby 9600 » Wed Dec 19, 2012 4:37 pm

When it comes to thinking about implementing digital down-conversion etc. in the FPGA there may be open source code we can reuse from the USRP and HPSDR.

In terms of GNU Radio and getting the signal processing blocks to make use of the Epiphany, I wonder if anything could be learnt from prior work with the Cell Processor and Nvidia GPU (~5M PDF).
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Re: Fast / medium fast : AtoD & DtoA

Postby tnt » Wed Dec 19, 2012 10:33 pm

Checkout http://myriadrf.org/

I'm planning to connect that when my parallella gets here ...
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Re: Fast / medium fast : AtoD & DtoA

Postby 9600 » Thu Dec 20, 2012 11:07 am

tnt wrote:Checkout http://myriadrf.org/

I'm planning to connect that when my parallella gets here ...


That's a great looking little board! Do you know how much they cost? I couldn't see mention of a price anywhere. And do you know if anyone is doing work on GNU Radio support, or is it purely being used with FPGA boards at the moment?
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Re: Fast / medium fast : AtoD & DtoA

Postby tnt » Thu Dec 20, 2012 1:02 pm

9600 wrote:That's a great looking little board! Do you know how much they cost? I couldn't see mention of a price anywhere.


Currently 299$ but they're trying to bring it down by like half once they get a bit more volume and they're also working to get it distributed via digikey / rs / ..

9600 wrote:And do you know if anyone is doing work on GNU Radio support, or is it purely being used with FPGA boards at the moment?


Well a good part of gnuradio support is the data transfers between host and dac and this board doesn't have any interface to a host ... (that would be custom FPGA logic on the parallela)

But it's the same transceiver chip than in the UmTRX ( an open hardware gsm basestation) and that one has gnuradio support opensource so it would be possible to extract the LMS control code and integrate it.
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Re: Fast / medium fast : AtoD & DtoA

Postby grahamh » Sat Dec 22, 2012 4:01 pm

That board uses the Lime Micro transceiver chip.
12 bit A->D, D-A at up to 40 Msps.

http://www.limemicro.com/download/LMS60 ... -1.2r0.pdf

Unfortunately Lime Micro is very "proud" of their chips at this time,
and is charging accordingly.

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Re: Fast / medium fast : AtoD & DtoA

Postby theover » Wed Feb 13, 2013 4:26 pm

Small-mass production of a nice TI/BB or AD AD and DA converter board is probably hard to design (analog part especially), but shouldn't need to be very expensive..
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Re: Fast / medium fast : AtoD & DtoA

Postby ipse » Thu Feb 14, 2013 8:27 pm

grahamh wrote:Unfortunately Lime Micro is very "proud" of their chips at this time,
and is charging accordingly.


Actually it's quite opposite - Lime Micro guys are doing their best to bring the price down. And they often make considerable discounts for open-source projects like our UmTRX. And for UmTRX we found that using their chip is both cheaper and faster then building the same from discreet components.
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