Re: [Discuss-gnuradio] trouble with QAM mod/ WX GUI Constellation Sink

There should be enough free resources, no need to pay big $$$ for books.
Other than what you list, have a look at
http://gnuradio.org/redmine/projects/gnuradio/wiki/SuggestedReading.

M

On 07/17/2015 06:19 PM, Bill Eaton wrote:
>> ... so I recommend you get an intro book to digital comms and map what
> they
>> say to the GNU Radio examples.
>
> Yeah. I was afraid it might come to this. Do you have any recommendations?
> Most digital comms textbooks are pretty pricey, and I'd hate to spend time
> and money on one that might not be a good fit.
>
> There are free options. There's the MIT course and the Lapidoth PDF book. I
> suspect I might prefer a real printed book with nice graphics.
>
> Thanks in advance,
>
> Bill Eaton
>
>
>
> -----Original Message-----
> From: discuss-gnuradio-bounces+billeaton=aeroantenna.com@gnu.org
> [mailto:discuss-gnuradio-bounces+billeaton=aeroantenna.com@gnu.org] On
> Behalf Of Martin Braun
> Sent: Friday, July 17, 2015 3:04 PM
> To: discuss-gnuradio@gnu.org
> Subject: Re: [Discuss-gnuradio] trouble with QAM mod/ WX GUI Constellation
> Sink
>
> On 17.07.2015 14:56, Bill Eaton wrote:
>>> What I meant was that you plot the result of your timing + phase
>>> recovery
>>
>>> into an XY plot, that would take care of those additional points
>> you're seeing.
>>
>> I have to confess that I don't even know what that means or how to go
>> about accomplishing it. I have to take baby steps because I'm a baby.
>> ;-) If you could point me to an example or some other things to try,
>> that would be helpful.
>
> OK, this is starting to get into basics of digital comms and this mailing
> list is probably not a good place for that.
>
> In brief, what you're plotting is the output of the QAM Mod -- which is
> *not* a QAM constellation, but rather the complex baseband signal that can
> be transmitted. This does include the QAM constellation.
>
>> I looked through the examples that ship with GNURadio and didn't see
>> anything obvious. Also, I looked through the GRC block tree to see if
>> I could try something. There's a Synchronizers section. Something from
> there?
>
> Try the examples in gr-digital.
>
>> You thought maybe it was oversampled. It occurred to me that maybe the
>> X-Y chart rate should be samp_rate/8, but I tried that and the chart
>> still look largely the same.
>
> That's not quite the right terminology, but if you plotted only a subset of
> the samples of your signal, you would see the constellation.
>
> It seems you're fine using GNU Radio itself, so I recommend you get an intro
> book to digital comms and map what the say to the GNU Radio examples.
>
> Cheers,
> Martin
>
>
>>
>>
>>
>> mlist_qam_constellation_xy.grc.png
>>
>>
>>
>>
>>
>>
>>
>> -----Original Message-----
>> From: discuss-gnuradio-bounces+billeaton=aeroantenna.com@gnu.org
>> [mailto:discuss-gnuradio-bounces+billeaton=aeroantenna.com@gnu.org] On
>> Behalf Of Martin Braun
>> Sent: Friday, July 17, 2015 1:20 PM
>> To: discuss-gnuradio@gnu.org
>> Subject: Re: [Discuss-gnuradio] trouble with QAM mod/ WX GUI
>> Constellation Sink
>>
>>
>>
>> On 17.07.2015 12:43, Bill Eaton wrote:
>>
>>> From Martin Braun:
>>
>>>
>>
>>>> My preference is to build the demod/sync chain with it's own blocks,
>>
>>>> and then just output the complex symbols
>>
>>>
>>
>>>> into either an X/Y plot (WX) or the QT Constellation Sink
>>
>>>
>>
>>> Even an X/Y plot ends up looking funny. I've attached a GRC file for
>>
>>> X-Y, and when you turn on persistence, it looks better. But it's very
>>
>>> strange. Maybe my bits_per_symbol is wrong. Or maybe the sample rate
>>
>>> for the X-Y chart should be different than the random sample rate?
>>
>>> Here's the 4 QAM X-Y.
>>
>>
>>
>> Your plot looks fine, it's just oversampled (but perfectly
>> time-synchronized, I'm guessing this is post-pulse shaping + noise?).
>>
>>
>>
>> What I meant was that you plot the result of your timing + phase
>> recovery into an XY plot, that would take care of those additional
>> points you're seeing.
>>
>>
>>
>> M
>>
>>
>>
>>
>>
>> _______________________________________________
>>
>> Discuss-gnuradio mailing list
>>
>> Discuss-gnuradio@gnu.org <mailto:Discuss-gnuradio@gnu.org>
>>
>> https://lists.gnu.org/mailman/listinfo/discuss-gnuradio
>>
>>
>>
>>
>>
>> _______________________________________________
>> Discuss-gnuradio mailing list
>> Discuss-gnuradio@gnu.org
>> https://lists.gnu.org/mailman/listinfo/discuss-gnuradio
>>
>
>
> _______________________________________________
> Discuss-gnuradio mailing list
> Discuss-gnuradio@gnu.org
> https://lists.gnu.org/mailman/listinfo/discuss-gnuradio
>
>
>


_______________________________________________
Discuss-gnuradio mailing list
Discuss-gnuradio@gnu.org
https://lists.gnu.org/mailman/listinfo/discuss-gnuradio