[Discuss-gnuradio] Help needed with message ports

[Volker Schroer]

Hi,

I'm trying to add an message port to my  working oot module fcdproplus 
to be able to control the frequency by an message from a qtgui sink.


I used the analog signal source as guide and implemented a message sink 
in the grc description, registered the in port, and defined  a handler 
function like described in the tutorial.


I can run my example of a simple fm receiver as before, but when I 
connect the message out port of a qtgui sink to my message in port of my 
oot block,


I get the following error message:


./FMRadio.py
INFO: Audio source arch: alsa
Funcube Dongle Pro+ found as: plughw:3,0
Dongle sucessfully initialized
Result of Action :+
FCDAPP 20.03
 Lna gain enabled
 Mixer gain enabled
If gain set to: 10
Set Frequency to: 94.3 KHz, corrected to: 94300 Khz
INFO: Audio sink arch: alsa
Traceback (most recent call last):
  File "./FMRadio.py", line 277, in 
    main()
  File "./FMRadio.py", line 266, in main
    tb.start()
  File 
"/usr/local/gnuradio/lib64/python2.7/site-packages/gnuradio/gr/top_block.py", 
line 109, in start

    top_block_start_unlocked(self._impl, max_noutput_items)
  File 
"/usr/local/gnuradio/lib64/python2.7/site-packages/gnuradio/gr/runtime_swig.py", 
line 5678, in top_block_start_unlocked

    return _runtime_swig.top_block_start_unlocked(r, max_noutput_items)
RuntimeError: fcdproplus(3): insufficient connected output ports (1 
needed, 0 connected)


These are the connections:


   ##
    # Connections
    ##
    self.msg_connect((self.qtgui_sink_x_0, 'freq'), 
(self.fcdproplus_fcdproplus_0, 'freq'))
    self.connect((self.analog_fm_demod_cf_0, 0), 
(self.audio_sink_0, 0))
    self.connect((self.analog_fm_demod_cf_0, 0), 
(self.audio_sink_0, 1))
    self.connect((self.fcdproplus_fcdproplus_0, 0), 
(self.low_pass_filter_0, 0))
    self.connect((self.fcdproplus_fcdproplus_0, 0), 
(self.qtgui_sink_x_0, 0))
    self.connect((self.low_pass_filter_0, 0), 
(self.analog_fm_demod_cf_0, 0))


If I remove the line

self.msg_connect((self.qtgui_sink_x_0, 'freq'), 
(self.fcdproplus_fcdproplus_0, 'freq'))



from my python script he error message disappears.

What am I doing wrong?


Any help is appreciated.

-- Volker


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Re: [Discuss-gnuradio] sound card output issue

[Andy Walls]

> From: Jean-Michel FRIEDT
> Date: Thu, 19 Jul 2018 16:17:10 +0200

> Indeed I have since checked any source of crosstalk and removed all links from
> source to audio sink but the one going to input number 3 and still the same
> issue is observed. However remplacing 9 Hz output (at 192000 Hz sampling
> rate) with 9.1 Hz solves the issue of the unexpected shape at the output
> of the sound card. It seems to me we have a strange relation when incrementing
> the NCO phase, but I fail to identify the cause of the problem, and why
> moving the frequency as the flowgraph is running solves the output shape.
> I thought that incrementing and decrementing the frequency defined as a
> 
> floating point number might lead me to a value slightly different from 90.0 
> kHz,
> 
[snip]

> On Thu, Jul 19, 2018, 4:49 AM Jean-Michel FRIEDT <
> address@hidden> wrote:
[snip]
> When first launched with an output frequency set to 90 kHz, the sound 
> card
> output looks like jmfriedt.org/snd1.png, ie with some spectral 
> component
> around 6 kHz whose origin I am unable to identify. If, using the 
> slider, I
> change the frequency and set it back to its original value of 90 kHz, 
> I get
> the fine output of jmfriedt.org/snd2.png which looks as good as I can
> expect from an output frequency so close to the Nyquist frequency.
[snip]

Having the benefit of hindsight, I'll guess it is a beat frequency,
since GCD(192000, 9) = 6000.

If a QT Freq Sink (with 8192 points and a Kaiser window) doesn't show
the 6 kHz component, I'd blame the sound card.

-Andy




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[Discuss-gnuradio] [GSoC'18][MIMO]: Updates of the week.

[Luca Schmid]

Hi all,
here is my blog post

of this week. I am currently planning the MIMO-OFDM receiver structure. My
blog post proposes a structure which uses as many stock OFDM blocks as
possible, but I am also thinking of other architectures with specialized
blocks. Next week, I am going to decide the final architecture with my
mentors.

Best
Luca
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Re: [Discuss-gnuradio] Enable/Disable TX ports in B210 in 2x2 setup

[Ayaz Mahmud]

Hi Marcus/Muller,

I was trying a simple flow graph to implement what you said earlier :
“
If it were *my* problem, I'd probably have a couple of vector sources of 
alternating 1s and 0s, interpolate them up to the desired sample rate
   X the switching interval, and multiply the stream going into the USRP by 
that stream of 1s and 0s.
“

To make things simpler, I am trying:

Vector source (0,1) multiplying with a sine wave. As an out put I want 1 period 
of sine wave (say 1kHz frequency) and the next period to be zero. I believe I 
need to set the sample rate and match this period with the vector source.

Can you just help be in deducing this please. Having hard time to sort this out 
☹

Thanks
Ayaz



From: Müller, Marcus (CEL)
Sent: Wednesday, July 18, 2018 6:34 AM
To: discuss-gnuradio@gnu.org; 
ayazmah...@hotmail.com; 
mle...@ripnet.com
Subject: Re: [Discuss-gnuradio] Enable/Disable TX ports in B210 in 2x2 setup

The Selector block comes from the "deprecated" category, and that for good 
reason: Don't use it, it causes a huge teardown/setup effort behind the scenes, 
and not all is guaranteed to work.

Follow Marcus' advice with the 0/1 multiplication and offset tuning.

Best regards,
the other Marcus
On Tue, 2018-07-17 at 23:06 +, Ayaz Mahmud wrote:
Hey Marcus,

I think the Selector block works well with my setup.

But I need a solution with which I can do a dynamic change in the input/output 
index. Can you let me know how is this possible

Ayaz

From: Ayaz Mahmud
Sent: Tuesday, July 17, 2018 4:39 PM
To: Marcus D. Leech; "Müller, Marcus 
(CEL)"; 
discuss-gnuradio@gnu.org
Subject: Re: [Discuss-gnuradio] Enable/Disable TX ports in B210 in 2x2 setup

Hi Marcus,

The situation still is same.

By browsing the archive I found some switching of blocks with SELECTOR. Is 
there any example that will be helpful on how this block actually functions ?

Thanks
Ayaz

From: Marcus D. Leech
Sent: Monday, July 16, 2018 1:26 PM
To: Ayaz Mahmud; "Müller, Marcus 
(CEL)"; 
discuss-gnuradio@gnu.org
Subject: Re: [Discuss-gnuradio] Enable/Disable TX ports in B210 in 2x2 setup

On 07/16/2018 02:05 PM, Ayaz Mahmud wrote:
Hi Marcus,

The issue is even I put the vector source toggling with 1 and 0s it transmit a 
signal. So I need something that will not transmit at all and switch between 
these 2 radio chains.

Thanks,
Ayaz
You're probably seeing the residual LO leakage during periods of "no transmit".

You can try using offset-tuning to move the leakage out-of-band:

Use:

uhd.tune_request(frequency,offset)

In the UHD sink for the "frequency" field.


From: Marcus D. Leech
Sent: Saturday, July 14, 2018 8:15 PM
To: Ayaz Mahmud; "Müller, Marcus 
(CEL)"; 
discuss-gnuradio@gnu.org
Subject: Re: [Discuss-gnuradio] Enable/Disable TX ports in B210 in 2x2 setup

On 07/14/2018 06:40 PM, Ayaz Mahmud wrote:
Hi Muller / Marcus,

I got the testing right now, but unfortunately it doesn’t work while I put it 
in my original file.

Here is the attached .grc where I have used vector source as input and multiply 
a period with 1 and then with zeros on one radio channel and opposite on the 
other.

Can you please have a look, and check if I am doing anything wrong ?

Ayaz

You're asking us to debug a very complex signal flow.

Why don't you try something a *lot* simpler to get the TX-flow-switching-logic 
correct first, and then work up from there.





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