Re: [Discuss-gnuradio] E100 Performance

[Marcus D. Leech]

On 06/30/2011 05:27 AM, Ralf wrote:
>
>
> Hi Marcus, thanks for your reply.
>
> That is very important for us to understand. How is the divider 512
> determined? It is in the FPGA I suppose.
> Where can read more about the FPGA besides this small text?
> http://www.gnu.org/software/gnuradio/doc/exploring-gnuradio.html#fpga
The FPGA supports a maximum interpolation ratio of 512.  Interpolation
ratios must be even.
>
> Can we only put proper divisors of 128MHz in terms of datarate into
> the UHD sink even above 250kHz?
Yup.  Only bandwidths that result in an even interpolation ratio from
the 128MHz DAC sample
  rate can be used.

>
> Actually we need to put ~10kbit/s of data onto a ~400kHz carrier. Is
> the GRC repeater the right functionality
> to interpolate the small datarate as shown in the attached setup?
>
Normally, if you need to use a "weird" sample rate, you'd use something
like the fractional interpolator
  block just before you send the stream to the UHD sink.  Do you mean a
carrier that is 400kHz in
  bandwidth, or a carrier at 400kHz center frequency?  The center
frequency isn't really relevant
  to this discussion, but the bandwidth is.




-- 
Principal Investigator
Shirleys Bay Radio Astronomy Consortium
http://www.sbrac.org