Gr-atsc

GNU Radio
1

The 2.x version of atsc_field_sync_demux has been proven to work.

The equalizer still looks like an issue with symbol/tag alignment -
A working 0.9 system demux syncs on a (FIELD-2) at 3277436, while a
failing 2.x system syncs at 3277487 - a difference of exactly
d_offset = ntaps - npretaps - 1 (51).

How to do the 0.9 alignment scheme:

inputs[1].index = output.index + offset; // align equalizer tags

in gr 2.x I have NO idea.

–Chuck

2

On Fri, Apr 27, 2007 at 10:15:35AM -0400, Chuck Swiger wrote:

inputs[1].index = output.index + offset; // align equalizer tags

in gr 2.x I have NO idea.

–Chuck

Chuck,

I’ll take a look at this as soon as I finish with the USRP power
management problem.

Thanks,
Eric

3

On Fri, 2007-04-27 at 08:48 -0700, Eric B. wrote:

On Fri, Apr 27, 2007 at 10:15:35AM -0400, Chuck Swiger wrote:

The 2.x version of atsc_field_sync_demux has been proven to work.

I’ll take a look at this as soon as I finish with the USRP power
management problem.

Actually I just got the 2.x equalizer to work (w00t!). Then verified the
2.x field sync checker as working ok.

That leaves just ONE module, and then we’ll be all up to date: the Bit
Timing loop.

Heheh.

–Chuck

4

On Fri, Apr 27, 2007 at 01:06:19PM -0400, Chuck Swiger wrote:

2.x field sync checker as working ok.

That leaves just ONE module, and then we’ll be all up to date: the Bit
Timing loop.

Heheh.

–Chuck

Excellent!

Eric

5

On Fri, 2007-04-27 at 13:06 -0400, Charles S. wrote:

2.x field sync checker as working ok.

That leaves just ONE module, and then we’ll be all up to date: the Bit
Timing loop.

Well, it turns out the bit_timing_loop already works so at this point
the 2.x gr-atsc is fully functional from antenna to mpeg output (with
warts, like a segfault in btl-fsd.py at the end of a decoding run).

I’ll put better instructions on how to use it in the
gr-atsc/src/python/README shortly. The biggest advantage is that now we
can easily run differnt combinations of modules to spread the work over
multiple processors, tied together with named pipes. The most obvious
improvement is probably using an fpll that takes complex input data.
Right now we have to interpolate by 3 (interp.py), shift to 5.75Mhz and
convert to float (xlate.py), then feed the fpll which does another
shift.

–Chuck

6

On Fri, Apr 27, 2007 at 02:33:01PM -0400, Chuck Swiger wrote:

On Fri, 2007-04-27 at 13:06 -0400, Charles S. wrote:

That leaves just ONE module, and then we’ll be all up to date: the Bit
Timing loop.

Well, it turns out the bit_timing_loop already works so at this point
the 2.x gr-atsc is fully functional from antenna to mpeg output (with
warts, like a segfault in btl-fsd.py at the end of a decoding run).

This is great news!

I’ll put better instructions on how to use it in the
gr-atsc/src/python/README shortly. The biggest advantage is that now we
can easily run differnt combinations of modules to spread the work over
multiple processors, tied together with named pipes. The most obvious
improvement is probably using an fpll that takes complex input data.
Right now we have to interpolate by 3 (interp.py), shift to 5.75Mhz and
convert to float (xlate.py), then feed the fpll which does another
shift.

–Chuck

Eric