Re: [Discuss-gnuradio] How to save/read sc8 format to/from file and convert it to complex float 32?

[Tom Rondeau]

On Thu, Jun 6, 2013 at 11:46 AM, Michael Ossmann <address@hidden> wrote:
> On Thu, Jun 06, 2013 at 11:27:02AM -0400, Josh Blum wrote:
>>
>> A block that implements this conversion w/ a configurable scalar would
>> be ideal.
>
> That would be very nice.  I've been using (for input from sc8 file to a
> complex flowgraph):
>
> UChar to Float -> Deinterleave => Float to Complex
>
> Since my samples are unsigned chars, this gives me an offset of
> approximately 128 that I can correct with Add Const either before
> Deinterleave or after Float to Complex (where it is 128+128j).
>
> Unsigned sc8 is the primary data format used by HackRF, so this may be
> interesting to other HackRF users.  The conversion is handled by
> gr-osmosdr when communicating with a HackRF directly from GNU Radio, but
> files transmitted or received via the hackrf_transfer utility are in the
> unsigned sc8 format.
>
> Mike

Most of our conversion blocks use Volk now, which also accepts a
scalar as part of the conversion process. Very efficient. The
uchar_to_float block doesn't use Volk, probably because there's no
currently existing Volk kernel for it.

It should be an easy mod to add the right kernel (if it doesn't exist)
and then use it in the block. Should speed things up a lot.

Tom