The flowgraph I provided (Fri, 12 Mar 2021 19:00:33 +0100) works with 4 sps (delay=58) and 8 sps (delay = 102)
On 15/03/2021 20:50, George Edwards
wrote:
Hi Mike,
Again, thanks for the great help and sorry to bother you again.
The Polyphase Clock Sync seems to have serious problems. It works well at 2 sps, but does not work for 4 or 8 sps. I replaced it with the recommended Symbol Sync block, which appears to work at the different sps based on constellation plot observations. However, when I tried to test the validity of its output against the input data, I couldn't find any delay to get a match. So I am left wondering if it is working well???
Any suggestions?
Thanks!George
On Fri, Mar 12, 2021 at 8:23 PM Mike Markowski <mike.ab...@gmail.com> wrote:
Hi George,
You used differential encoding but forgot differential decode. I added
the block in the attached. (I disabled your file creation and displayed
to gui, easier for me to check.)
Little things are the hardest to spot. :-)
Mike Markowski
On 3/12/21 4:46 PM, George Edwards wrote:
> Hi Mike,
>
> Thanks for your help!
>
> As I mentioned in my email, my flowgraph consists of some of the blocks
> in the example. I dropped some of the blocks because I am doing concept
> testing to ensure I know how to set parameters for the blocks. In
> terms of delays, that is not a problem. I am dumping the outputs into 2-
> file sinks, so in post processing I can compensate for that. The problem
> is that the tx and rx data are not the same, so I am missing in setting
> parameters.
>
> Thanks again!
> George
>
> On Fri, Mar 12, 2021 at 3:31 PM Mike Markowski <mike.ab...@gmail.com
> <mailto:mike.ab...@gmail.com>> wrote:
>
> I can't make out details in your image, George, but attach one I made
> when working through the tutorial and works just now under gnuradio
> 3.8.1.0. Like someone else mentioned in another reply, I found the
> delay to be 58 and set it as the default in the attached flowgraph.
> Zoom in on the bit stream plot and allow a second or two after changing
> delay to see the effect.
>
> Hope this helps,
> Mike Markowski
>
> On 3/12/21 10:37 AM, George Edwards wrote:
> > Hello,
> >
> > I cannot get the combined Constellation Modulator/Decoder as
> shown below
> > to work. The figure below is an example from the online Guided
> Tutorial
> > PSK Demodulation.... I leave out the Equalizer, Costas Loop
> blocks, the
> > channel was set to pass the signal unimpaired and the Poly Clock
> Sync
> > was set for Output sps=1. The constellation plot of the output of
> the
> > Poly Clock Sync is perfect. Now, in the flowgraph below, the signal
> > entering the Constellation Modulator and that leaving the
> Constellation
> > Decoder are routed into Time Sinks for display. I route these
> signals
> > into File Sinks so I can print them and compare 1's and 0's. The
> results
> > show they are not the same. I passed Constellation Rect.Object
> > parameters to both the Constellation Modulator and Decoder, which
> seems
> > logical to me, but I could be wrong???
> > Will appreciate any help you can provide because what enters the
> > modulator should be the same as what is leaving the demodulator.
> > Regards,
> > George
> >
> > image.png
>
