[Discuss-gnuradio] Re: Weaver vs. Hilbert

[Chuck Swiger]

At 06:49 AM 2/15/2005 +0100, you wrote:
> In hardware a Weaver modulator avoids
> the need for the phase shifting baseband
> filters.
> What is the reason for using a Weaver
> modulator
> (http://webpages.charter.net/cswiger/weaver_gen.py)
> in an SDR?
> Is it faster than an Hilbert
> transformer?
> (http://comsec.com/wiki?SingleSideBandModulator)

Hi Thomas - no reason other than it's the only thing I've
gotten to work so far ;)    I tried a phasing demodulator
and ran into some problems, likely from not understanding
how to use the hilbert transform gr.hilbert_fc().   Putting
together a weaver graph actually worked, and after combining
a few parts into gr.freq_xlating_fir_filter_xxx() it really became
effecient enough to use, plus sounds good.    Turning to
transmitting, I just took what's working so far and turned it
around.   Other strategies will likely work much better. The
above script does work, but is very inefficient as I can't
(or don't know how to) combine the rf mixers and filters
and decimators, or interpolators in the transmitting case,
into one processing block like in the demodulator.

An instructive app note:
http://www.standardproducts.philips.com/support/appnotes/analog/pdf/an1981.pdf

I'll  try your script out shortly.

--Chuck