[hpsdr] Dumb question - HPSDR sound card

[Chris Albertson]

Thanks for pointing out the bit about the truncation.
I'll look in the specs again.

But this thread "Dumb question - HPSDR sound card"
was about what can be done for under $100 that is
better than a PCI sound card.  

You are right.  It all depends on the goals.


My area is software.  (I work with spacecraft
telemetry.)  Maybe I should say with that.
I got here because I'm
hunting for an RF front end so I can experiment
with SDR software.  What I'd really like to see
and maybe I can help with is development
of a common software interface to all the various
SDR hardware projects.  So far GNU Radio looks
good.  A fairly easy to use toolbox for SDR
experimenters but certainly not for end users


--- Lyle Johnson <kk7p at wavecable.com> wrote:

> > The GNU Radio and HPSDR people are using FPGA chips to
> > do this. Why bother if you can buy a programmable
> > decimater, mixer, A to D and so on for $15.
> 
> In a word, performance.
> 
> The Analog Devices Digital down converter chips with decimator, etc.,
> 
> were examined very closely for use in Mercury.  Unfortunately, there
> is 
> truncation that occurs inside the chip's CIC filters.  This is fine
> for 
> the intended application of a cellphone base station, but throws away
> 
> some dynamic range that we really want in an HF receiver.  So, the 
> decision was made to use the FPGA approach.
> 
> Which is not to say that an interesting receiver couldn't be made
> with 
> some of these chips, just that you have dig deeply and look carefully
> 
> before you decide one approach or the other is right, based on your 
> design goals.
> 
> Enjoy!
> 
> Lyle KK7P
> 
> 


Chris Albertson
  Home:   310-376-1029  chrisalbertson90278 at yahoo.com
  Office: 310-336-5189  Christopher.J.Albertson at aero.org


 
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