[USRP-users] SBX daughtercard bandwidth problem..!!

Marcus D. Leech mleech at ripnet.com
Sun Feb 12 23:17:03 EST 2012

> Thanks Josh and Ian Buckley....:) So it means:
> 1. I cannot set the decimation or interpolation to "1" in simulink
> SDRu block? or in other words i        cannot get the sampling rate of
> 100 MSPS?? :( 
> 2. Is there any way using Simulink SDRu block??
> Regards 
> Salman Dinani
There's no standard mode that allows 100Msps into the host.  Doing so
would require 4-bit I and 4-bit Q,
  which reduces your dynamic range to 32dB, which isn't a lot.

But even assuming for a moment that such a mode was possible, *doing*
anything with samples arriving
  at 100Msps is going to be a significant challenge, particularly using
any kind of generic framework
  such as Gnu Radio or Simulink.  I know the GMRT people are processing
samples arriving at up to
  64Msps, and they had to custom-code a lot of things, and their
samplers operated on the PCIe bus,
  not ethernet.  They had the advantage of double-buffered
large-transfer-size DMA, and very careful

Further, the maximum analog bandwidth coming out of most daughtercards
is only 40MHz, so 100Msps
   doesn't give you any advantage.

Just my small contribution.

Principal Investigator
Shirleys Bay Radio Astronomy Consortium

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