Re: [Discuss-gnuradio] ATSC fixups

[Johnathan Corgan]

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.

Agree.

> 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
http://corganlabs.com

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