This is awesome! I just pulled master and I am recompiling it right now. Thanks you both so much for the help.
I clearly still have some tuning work to do either way, but it would be great to get move up to 3.7. I will let you know if this clears it up. I have my fingers crossed that it will. > On Nov 4, 2014, at 8:19 PM, Andy Walls <[email protected]> wrote: > > On Mon, 2014-11-03 at 22:13 -0500, Luke Berndt wrote: >> Thanks Andy! Good catch - I made the changes you suggested. I was just >> doing a simple back of the envelope calculation to come up with >> channel size. It does look like cleans things up and adding the >> waterfall graphs does make it easier to see. Unfortunately, it does >> seem to change the decoding. I am still getting the same amount of CRC >> errors. >> >> Did the overall signal look right, like something that should be decodable? > > So I put the output of the FLL into a quad demod block and compared its > output to the PLL Freq det output. They are pretty much in line, except > the quadrature demod block output shows occasional burst of noise for a > few symbol times where the transmission must have stopped and restarted. > The PLL freq detect block just makes something up during these times. > So that seems generally OK. > > > >> Anything else I should try? > > Your PLL freq detector block output is swinging between -2 and 2. You > might want to reduce the max and min freq by a factor of 2, so that the > clock recovery block sees inputs limited to +/- 1.0. See Nick's > recommendation here: > http://lists.gnu.org/archive/html/discuss-gnuradio/2014-10/msg00473.html > <http://lists.gnu.org/archive/html/discuss-gnuradio/2014-10/msg00473.html> > > So after i did that, what I really noticed is that the correlator is > just not marking preambles properly. See the top plot of the attached > to window shots: Preamble_marked_late_twice.png and > Preamble_marked_early.png > > If the deinterleaver and/or crc block isn't searching around for where > the preamble really is, well that would explain it. > > Regards, > Andy > >> - Luke >> >>> >>> Hi Luke, >>> >>> I have not built the SmartNet blocks yet, but: >>> >>> Your low pass filter looks way too wide and you'll get aliases when you >>> decimate by 185. 2 Msps / 185 = 10.81 ksps, so the Nyquist frequency is >>> 5.405 kHz. I winged this is as a low pass filter and things looked >>> better: >>> >>> firdes.low_pass_2(1, samp_rate, 4500, 1000, 60, firdes.WIN_HANN, 6.76) >>> >>> The 60 dB down may be overkill, you can make it smaller for a filter >>> with less delay. >>> >>> I found an offset slider value of -15k made things look about centered >>> manually. >>> >>> You might want to put a waterfall sink before and after the FLL >>> Band-Edge filter to observe how it is making the spectrum wobble around >>> a little. If you change your offset slider, you can see the FLL >>> band-edge filter centering things back up; so that looks like it is >>> working. >>> >>> Regards, >>> Andy >>> >> > > <Preamble_marked_late_twice.png><Preamble_marked_early.png>
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