Re: [Discuss-gnuradio] ztex USB-FPGA board

[Tim Newman]

Luke Kenneth Casson Leighton wrote:
> http://shop.ztex.de/product_info.php?cPath=21&products_id=28
>
> dear gnuradio developers,
>
> i was searching on opencores.org to see if there was a SoC that
> incorporates an FPGA(-like) device with an open core, and i
> accidentally encountered the above USB-FPGA board.  it has a Cypress
> CY7C68013A/14A 480mb/s USB-2 Microcontroller and a Xilinx Spartan-3
> XC3S400 FPGA.  it is also accompanied by a developer board:
>
>   http://www.ztex.de/usb-fpga-1/exp-1.1.e.html
>
> the price for the USB-FPGA is an incredibly-low $EUR 70, and the
> developer board is only $20.
>
> so my primary question is: is this USB-FPGA board (apart from the
> issue of connecting to A-D / D-A boards) suitable for use to do an
> 802.11b transceiver?  is it fast enough?
>
> many thanks,
>
> l.
>
>
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This is a fairly loaded question, as it completely depends on WHERE you 
implement certain portions of the 802.11b waveform.  The primary 
bottleneck is the USB bus, and you can't get 20 MHz of bandwidth over 
that bus.  BBN and whoever else worked on the current GNU radio 802.11b 
waveform solved this by moving the despreading to the FPGA.  This is 
just one example.  In the end, it completely depends on where you 
implement the latency and bandwidth sensitive components of the waveform. 

Tim