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Re: [Discuss-gnuradio] ATSC fixups

From: Andrew Davis
Subject: Re: [Discuss-gnuradio] ATSC fixups
Date: Wed, 7 Aug 2013 21:43:09 -0500

Yeah, That doesn't seem to be anything I messed with, anyway I pushed another commit that if compiles for everyone could be merged into the Gnuradio master. I found that the "Magic coupling constant" isn't so magic and can be complexly removed and replaced with an AGC block set to a reference level of 4 ( the mean value of the pseudo-random 1 3 5 7 levels of the ATSC PAM signal ). So I separated that out of the fpll block. For some reason I simply cannot make a complex PLL that works the same way the old PLL works, I get close but i'm still missing something, once I get that figured out it will shave off approximately 12% from the decoding time ( thanks to the new performance counters I can now easily track what my fix-ups are doing and whats left before real-time decoding ).

Thanks you,

On Wed, Aug 7, 2013 at 4:11 PM, Souryal, Michael <address@hidden> wrote:

I tried building this later push and this is as far as I got.


[ 70%] Building CXX object gr-qtgui/lib/CMakeFiles/gnuradio-qtgui.dir/TimeDomainDisplayPlot.cc.o

/raid/souryal/gnuradio-atscfixup/gr-qtgui/lib/TimeDomainDisplayPlot.cc: In member function ‘void TimeDomainDisplayPlot::setSemilogy(bool)’:

/raid/souryal/gnuradio-atscfixup/gr-qtgui/lib/TimeDomainDisplayPlot.cc:358: error: ‘class QwtScaleDiv’ has no member named ‘upperBound’

make[2]: *** [gr-qtgui/lib/CMakeFiles/gnuradio-qtgui.dir/TimeDomainDisplayPlot.cc.o] Error 1

make[1]: *** [gr-qtgui/lib/CMakeFiles/gnuradio-qtgui.dir/all] Error 2

make: *** [all] Error 2


It doesn’t look related to ATSC, though.


From: discuss-gnuradio-bounces+souryal=address@hidden [mailto:discuss-gnuradio-bounces+souryal=address@hidden] On Behalf Of Andrew Davis
Sent: Monday, August 05, 2013 3:37 PM
To: M. Ranganathan
Cc: GNURadio Discussion List
Subject: Re: [Discuss-gnuradio] ATSC fixups


OK, pushed, could you see if that works better?


Thank you



On Mon, Aug 5, 2013 at 2:50 PM, Andrew Davis <address@hidden> wrote:

It was removed and left in fpll.h, i'll push a fix in just a bit, in the meantime you could just remove the include line from fpll.h


Thank you



On Mon, Aug 5, 2013 at 1:46 PM, M. Ranganathan <address@hidden> wrote:


I git cloned the atscfixup branch and tried building it. Here's as far as I got:

In file included from /users/mranga/gr-atscfixup/gnuradio/gr-atsc/lib/receiver/atsc_fpll.cc:27:
/users/mranga/gr-atscfixup/gnuradio/gr-atsc/include/gnuradio/atsc/fpll.h:32:44: error: gnuradio/atsc/diag_output_impl.h: No such file or directory

Perhaps this file was accidentally left out of the repository (?)



On Mon, Jul 15, 2013 at 10:56 PM, Johnathan Corgan <address@hidden> wrote:

On 07/15/2013 07:01 PM, Andrew Davis wrote:

> After this stuff and the reorganization a simple diff would not have
> saved much, also i'm working on 'atsc_tx.py',so 'all_atsc.py' would
> be confusing, hence the name change.

First, let me say that I'm very happy this code is getting some
attention. It was originally written to use the low-IF output of a TV
tuner and ADC, and also when GNU Radio only had a single-threaded
scheduler.  Later, it was only minimally modified to use the USRP
complex baseband IQ output. (I wasn't around GNU Radio at the time and
the above is only what I surmise by looking at the code history.)

The changes you describe are more like it would have been written had
the USRP existed at the time.

The all_atsc.py file was a work-in-progress effort by Ben Reynwar that I
merged in, but he and I never finished what we were going to do with it.

> Also the other scripts seem unnecessary with the new
> thread-per-block sceduler, the also seem to cause a lot of beginners
> confusion. So I felt they needed to go.


> I have also built a ( semi ) working complex fpll for gr-atsc, this
> removes the need for up-converting and the filtering after the
> current fpll, my next atsc_rx will need the new script style. After I
> finish updating the bit timing loop we will be almost real time I
> believe!

The upconversion and filtering is a large CPU waste when it could be
done at baseband, but it seems this was just a quick-and-dirty way to
get the baseband IQ from a USRP to look like a low-IF output instead in
order to re-use what was already written and working.

Real-time execution would be a welcome accomplishment!

> P.S. I could still just do the diff to the old all_atsc.py and rename
> if you want.

No need.

By the way, before any of this can be merged, we'll need a copyright
assignment from you.  I'll email you off-list about how this works.

Thanks again for working on this.

Johnathan Corgan
Corgan Labs - SDR Training and Development Services


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