Re: [Discuss-gnuradio] AD9862 Functionality

[Brian Padalino]

Eric,

Thanks for all the answers so far.  I am really getting a grasp of
everything going on within the USRP.  I really appreciate it.

On 2/20/07, Eric Blossom <address@hidden> wrote:
> The code in usrp_standard.cc controls the FPGA interpolation rate.
> The rates do not have to be powers of two.  From the user point of
> view the net interpolation rate must be in [4, 512] and a multiple of 4.
>
> This is all controlled in usrp_standard.cc.  I suggest that you take a
> look at it ;)

I have been perusing it, and I will definitely take a closer look.  Thanks!!

> > Or is a modulator block required to do things in powers of 2 when
> > connected to a USRP?
>
> No.  You might want to start looking at for example, the gmsk
> modulator/demod: gnuradio-core/src/python/gnuradio/blksimpl/gmsk.py

I suppose I should clarify the rates.  All bandwidths have to be some
decimation from 64Msps that is also divisible by 4.  For example, I
could not choose to run a bandwidth of 1.2MHz through the USRP.

Is there an inherent sample frequency of 8Msps when dealing with the
USRP?  It seems with 16-bit complex data, the USB is able to transfer
8Msps.  If I set the GMSK modulator to have 20 samples per symbol,
will that give me an effective bandwidth of 400kHz?

Thanks,
Brian