Re: [Discuss-gnuradio] gr.firdes_hilbert () usage

[Eric Blossom]

On Wed, Nov 24, 2004 at 03:35:24PM -0800, Matt Ettus wrote:
> Quoting Dan Gisselquist <address@hidden>:
> 
> > Chuck,
> >
> > Now I follow what you are doing ... thanks for the web link--it really
> > helped explain things for me.
> >
> > You're trying to pull off a single sideband from a complex sampled
> > input.  (At least, that's what the phasing method of image rejection in
> > the web-link discusses ...)  May I suggest an alternate approach?  Just
> > use a complex filter:
> >
> 

On the Tx side, there's also the Weaver method.  We use it in the the
ATSC Tx code.  There are two very small blocks that would need to be
ported, GrWeaverModHead and GrWeaverModTail.  The unported versions
are in CVS: gnuradio-core/src/lib/general

/*!
 * \brief Head block of a Weaver SSB/VSB modulator
 *
 * Let the input rate be Fsym.  Complex mix with cos/sin of Fsym/4 & interpolate
 * by 2.  This is typically used like this:
 *
 *                      |---> matched filter --->|
 * ---> GrWeaverModHead |                        | GrWeaverTail --->
 *                      |---> matched filter --->|
 */


/*!
 * \brief Tail  block of a Weaver SSB/VSB modulator
 *
 * Complex mix with cos/sin of IF_freq & sum components.
 * See also GrSSBMod, which is basically the same as this
 * except it expects I & Q to to be a single gr_complex stream
 *
 * This is typically used like this:
 *
 *                      |---> matched filter --->|
 * ---> GrWeaverModHead |                        | GrWeaverTail --->
 *                      |---> matched filter --->|
 */


Eric