On Wed, Dec 02, 2015 at 02:41:29PM +0100, Michael Kramer wrote:
I've tried your suggestion but again I'm a little bit confused by the
results. The attached Wave2 is produced if I decimate by 100 in my Low
Pass Filter right before the Hilbert -> Quadrature Demod. If I don't
before, but after the second Quadrature Demod I get Wave3. So I guess
I'm doing right by decimating within the Low Pass Filter.
Agreed. Wave2 is very close to the result I was hoping for. Try
increasing the number of taps in the Hilbert block by 2x to 4x.
I can even more or less see my data inside Wave2 (even though it seems
to be inverted. it looks like its 00000111111111001110110 instead of
111111000000000110001001), but I'm not really able to center it since
the upper spikes are crossing zero sometimes.
You might try using DC Blocker for this. You'll probably have to
increase the default length by about 3x.
Also I wanted to ask if my calculation is correct: I have sampled with
2MHz. The bitrate (should be) 2400. So if I want 4 or 5 samples per
symbol for the Clock recovery I need to resample to 4*2400=9600 or
5*2400=12000.
Yes. For best clock recovery results, I usually aim for 2 to 4 samples
per symbol. If you decimate by 400 instead of 100, that should give you
5 ksps or 2.0833 samples per symbol. (And, actually, if you do that,
you may not need to set the parameters for Hilbert and DC Blocker so
high.)
Mike