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 Mon, 2014-11-03 at 22:13 -0500, Luke Berndt wrote:
Thanks Andy! Good catch - I made the changes you suggested. I was justSo I put the output of the FLL into a quad demod block and compared itsoutput to the PLL Freq det output. They are pretty much in line, exceptthe quadrature demod block output shows occasional burst of noise for afew 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.
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
Did the overall signal look right, like something that should be decodable?
Anything else I should try?Your PLL freq detector block output is swinging between -2 and 2. Youmight want to reduce the max and min freq by a factor of 2, so that theclock recovery block sees inputs limited to +/- 1.0. See Nick'srecommendation here:http://lists.gnu.org/archive/html/discuss-gnuradio/2014-10/msg00473.htmlSo after i did that, what I really noticed is that the correlator isjust not marking preambles properly. See the top plot of the attachedto window shots: Preamble_marked_late_twice.png andPreamble_marked_early.pngIf the deinterleaver and/or crc block isn't searching around for wherethe preamble really is, well that would explain it.Regards,Andy
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
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
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