Re: [Discuss-gnuradio] r/s encoding and padding on gmsk

[Eric Blossom]

On Sat, May 19, 2007 at 01:48:33PM -0400, Brian Padalino wrote:
> >
> >In any case,  in reading the associated python code, I noticed that the
> >data sent over the USB seems to have to be in multiples of 128, but it
> >also seemed to imply that it had to be multiples of 512. The current
> >padding mechanism seems to take into account the bits/sample and
                                                           ^
                                                           |
                      Should be bits/symbol----------------+

> >samples/symbol as well.
> 
> >From a strictly USRP point of view, the FX2 only knows how to do burst
> transfers of 512-byte packets over USB and to/from the FPGA.  These
> are the actual samples that are going to get interpolated and sent on
> out the DACs, so this takes into consideration both bits/sample and
> samples/symbol.
> 
> 
> Someone should probably qualify my statement, but as far as I know -
> it seems like it should work.  Give it a shot.
> 
> Brian
> 

This should work.  You just need to adjust your padding such that the
final output of your modulated packet is a multiple of 128 complex
samples (== 512 bytes across the USB).  [This restriction is one of
the things that will be fixed in the inband signaling code...]

Eric