Re: [Discuss-gnuradio] Floating point FFT usage - suppress half of it?

[CEL]

Hi,
On Mon, 2018-03-19 at 22:29 -0400, Brad Hein wrote:
> 
> - Is it true then that if I have a 100-bin FFT, that each of the
> "left 50" equals the negative of its corresponding right-side bin? 
> 
No, it's their complex conjugate.

> - Is there any use for "negative frequencies" if my goal is to simply
> measure the ESD for each of the frequency bins?

In your case, they contain exactly the same energy as their positive
counterparts. That's the case because your signal is real. In the
general complex case, negative and positive frequencies carry
independent information!

> - If I want to get 48 usable frequency bands, each corresponding to a
> 0-1k, 1k-2k, 2k-3k, etc do I actually need a 96 bin FFT due to the
> mirroring?

Think of the DFT as converter from N time samples to N frequency
samples. So, if only half of them contain non-redundant information and
you need M, then N=2M.


> - Do the negative frequencies correspond to a phase difference
> compared to the positive frequencies - in other words if I have two
> 2600Hz signals that are out of phase by 180 degrees, would this be
> reflected in the negative vs positive bin associated with 2600Hz? 

not quite sure what you want to say. There's no "freedom" that your
signal has here: if it's real, then the negative DFT bins are the
conjugate of the positive ones, as said. 

Remember, the DFT gives you complex numbers, with an amplitude and a
phase. That phase represents your sinusoid's phase. It's as easy as
that – and as complicated as that.

At this point, I'd strongly recommend you get a good textbook intro to
signal theory; it's not like any of this is "random knowledge that only
very few expert have", it's written in any textbook that introduces the
DFT.

Best regards,
Marcus

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Re: [Discuss-gnuradio] [GSoC18] Application period started!

[Felix Wunsch]

Hi all,


this is just a quick reminder that you have one week left to submit your
proposals! And again: Do not wait until the last second! Reach out to us
and discuss your ideas on this list, we are happy to help you refining
your project scope and milestones.


Cheers,
Felix



On 03/12/2018 11:05 PM, Wunsch, Felix (CEL) wrote:
>
> Hi all,
>
>
> the application period has started today and we are eagerly awaiting
> your draft proposals!
>
>
> Please make sure to submit as early as possible and (optimally) also
> well before the deadline (March 27) - we really want to help you to
> craft a good proposal and to set you up for success right from the
> start. But that needs time, so better get right on it and start
> writing! An example from a successful project as well as instructions
> and tips for writing a good proposal can be found in our wiki [0].
>
>
> If you have further questions about writing your proposal, please use
> this mailing list, we're happy to help!
>
>
> Cheers,
>
> Felix
>
>
> [0] https://wiki.gnuradio.org/index.php/GSoC
>
>
>
>
>
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-- 
Karlsruhe Institute of Technology (KIT)
Communications Engineering Lab (CEL)

Felix Wunsch, M.Sc.
Research Associate

Kaiserstraße 12
Building 05.01
76131 Karlsruhe

Phone: +49 721 608-46276
Fax: +49 721 608-46071
E-Mail: felix.wun...@kit.edu

www.cel.kit.edu

KIT -- University of the State of Baden-Württemberg and
National Laboratory of the Helmholtz Association

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Re: [Discuss-gnuradio] GSoC 2018: Compas Widget

[Nicolas Cuervo]

Hello Valian,

Thank you for your interest in GNU Radio and GSoC!

that compass you put together seems like a good start for what we'd like to
have. Answering your question: optimally we'd like to have all the ones
that are listed (and probably even more if we see the necessity or
applicability of a new one along the way!) But for the sake of clarity
regarding GSoC, we expect neither a coding wonder nor a very small task. My
point is: if you are interested in working on this, don't hesitate to draft
a proposal. We will analyze your proposed milestones and assess how real
are the deliverables that you propose. If we see that your focus is too
broad, or that your workload is too low/high, we will be very clear on that
as well. Just one QtWidget seems too little for a Summer of Code (you
already have the compass halfway there!) and assessing all the proposed
points might or might not be too much work. It depends on how you would
plan to approach the problem in question and your experience with all the
frameworks involved.

Have a look at the GSoC Student Guide [1], which has a section on "writing
a proposal", or keep asking questions regarding this topic if you still
need a bit more clarification. Keep in mind that the application deadline
is *March 27, 2018 at 18:00* *(CEST), *so you are better off planning
accordingly and parallel your interests.

Regards,
- Nicolas

[1]
https://developers.google.com/open-source/gsoc/resources/guide#student_manual


On Tue, Mar 20, 2018 at 3:35 AM, Valian Masdani 
wrote:

> Greetings,
>
> I've read the ideas list for GSoC 2018 and I somehow managed to get the
> compass working in Qt using the QPainter coordinate system, and I think
> this can be appliable in the Qt Widgets Improvement idea. I've attached the
> screenshot of the widget in this mail. I haven't learned how to change the
> font size and such, though. I also read that you also need the MPEG decoder
> and Matrix display in the subtopic, not just the compass. Do you need all
> of them or just one of them?
>
> Best regards,
> Valian Masdani
>
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[Discuss-gnuradio] FSK transmitter tutorial

[Murray Thomson]

Hi,

I would like to build an FSK modulator/demodulator. I'm using file
sink/sources for the moment. I need to be able to specify the two
frequencies, baud rate and sample rate (ideally at runtime).
I started with the gr-tutorial for qpsk, hoping to replace the
modulation/demodulation with gfsk blocks, but I didn't get the result I was
hoping for. I don't fully understand the gfsk module or how to change the
frequencies after the modulation. I tried the fsk burst modem example, but
it's not what I want. I would rather not use PDUs and I don't want to
transmit in bursts.
 I would really appreciate if someone could point me to a tutorial or
example on this. These are the resources I have read so far:

https://github.com/gnuradio/gr-tutorial/blob/master/examples/tutorial7/mpsk_stage6.grc
https://nccgroup.github.io/RFTM/fsk_transmitter.html
https://www.reddit.com/r/GNURadio/comments/3u5zp2/gnu_radio_gfsk_modulation_rate_deviation/
http://www.indigresso.com/wiki/doku.php?id=opentag:radios:testing_with_gnuradio
https://oshearesearch.com/index.php/2015/05/31/building-a-burst-fsk-modem-in-gnu-radio-with-message-lambda-blocks-and-eventstream/

Many thanks,
Murray
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Re: [Discuss-gnuradio] FSK transmitter tutorial

[Dan CaJacob]

Check out the FSK : Digital section of
https://wiki.gnuradio.org/index.php/SignalProcessing Shows you how to set
up some variables you'll need. Freq modulator and quadrature demodulator
are important. So is filtering.

On Tue, Mar 20, 2018 at 7:49 AM Murray Thomson 
wrote:

> Hi,
>
> I would like to build an FSK modulator/demodulator. I'm using file
> sink/sources for the moment. I need to be able to specify the two
> frequencies, baud rate and sample rate (ideally at runtime).
> I started with the gr-tutorial for qpsk, hoping to replace the
> modulation/demodulation with gfsk blocks, but I didn't get the result I was
> hoping for. I don't fully understand the gfsk module or how to change the
> frequencies after the modulation. I tried the fsk burst modem example, but
> it's not what I want. I would rather not use PDUs and I don't want to
> transmit in bursts.
>  I would really appreciate if someone could point me to a tutorial or
> example on this. These are the resources I have read so far:
>
>
> https://github.com/gnuradio/gr-tutorial/blob/master/examples/tutorial7/mpsk_stage6.grc
> https://nccgroup.github.io/RFTM/fsk_transmitter.html
>
> https://www.reddit.com/r/GNURadio/comments/3u5zp2/gnu_radio_gfsk_modulation_rate_deviation/
>
> http://www.indigresso.com/wiki/doku.php?id=opentag:radios:testing_with_gnuradio
>
> https://oshearesearch.com/index.php/2015/05/31/building-a-burst-fsk-modem-in-gnu-radio-with-message-lambda-blocks-and-eventstream/
>
> Many thanks,
> Murray
>
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-- 
Very Respectfully,

Dan CaJacob
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[Discuss-gnuradio] Callback Function in Blocks for C++

[Luis Felipe Albarracin Sanchez]

Hello Everyone,

I am trying to build a new block from scratch, that allows me to change
parameter values while the flowgraph is running.

I have found that for the .XML code i must use:

"Function"($XXX)

My question is, in the c++ code , besides creating the function and
applying values to the parameter, do i need to do something else so the
callback work?

Thanks for the response.
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Re: [Discuss-gnuradio] Callback Function in Blocks for C++

[Dave NotTelling]

Take a look at
https://github.com/gnuradio/gnuradio/blob/master/gr-blocks/include/gnuradio/blocks/throttle.h#L57
,
https://github.com/gnuradio/gnuradio/blob/master/gr-blocks/lib/throttle_impl.h#L49,
and
https://github.com/gnuradio/gnuradio/blob/master/gr-blocks/lib/throttle_impl.cc#L70
as an example.  The XML is at
https://github.com/gnuradio/gnuradio/blob/master/gr-blocks/grc/blocks_throttle.xml#L13

On Tue, Mar 20, 2018 at 12:40 PM, Luis Felipe Albarracin Sanchez <
lfasanc...@gmail.com> wrote:

> Hello Everyone,
>
> I am trying to build a new block from scratch, that allows me to change
> parameter values while the flowgraph is running.
>
> I have found that for the .XML code i must use:
>
> "Function"($XXX)
>
> My question is, in the c++ code , besides creating the function and
> applying values to the parameter, do i need to do something else so the
> callback work?
>
> Thanks for the response.
>
>
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Re: [Discuss-gnuradio] Callback Function in Blocks for C++

[Michael Dickens]

Hi Luis - You also have to make sure the function is passed through from
C++ to Python via SWIG, which means that it must be in the public header
in the OOT, not just the private header. Hope this helps! - MLD
On Tue, Mar 20, 2018, at 12:40 PM, Luis Felipe Albarracin Sanchez wrote:> Hello 
Everyone, 
> I am trying to build a new block from scratch, that allows me to
> change parameter values while the flowgraph is running.> 
> I have found that for the .XML code i must use:
> 
> "Function"($XXX)
> 
> My question is, in the c++ code , besides creating the function and
> applying values to the parameter, do i need to do something else so
> the callback work?> 
> Thanks for the response.
> 
> _
> Discuss-gnuradio mailing list
> Discuss-gnuradio@gnu.org
> https://lists.gnu.org/mailman/listinfo/discuss-gnuradio

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Re: [Discuss-gnuradio] Accessing the ADI registers on B200mini

[Firdavs Pulat]

Hi Marcus,

Could you please elaborate on the "extend the Gnu Radio multi_usrp" part?
Maybe you could point me to some examples one how to set these (I assume
others must have played around with them since it's so essential), or
documentation on how that's done? I'm just not sure where/how in the
usrp_source impl source code I would set them. I have been looking online,
but haven't found anything of use yet.

Thank you!


On Thu, Mar 8, 2018 at 10:58 AM, Marcus D. Leech  wrote:

> On 03/08/2018 10:43 AM, Firdavs Pulat wrote:
>
>> Hi all,
>>
>> Are there APIs as part of gnuradio that give access to the low level ADI
>> registers (to both probe, and set)? For instance, I'm trying to see if the
>> AGC is currently turned on on B200mini, and if it's, what kind of mode it
>> is on (e.g., slow or fast). Looking at it the USRP manual online, I see
>> functions like set_agc, set_agc_mode, etc. I just don't have any idea
>> how/where to actually use/set these. Could anyone please help me out?
>>
>> Thanks!
>>
>>
>> No need to tinker with ADI registers.
>
> The multi_usrp API provides access to a set_rx_agc function:
>
> https://files.ettus.com/manual/classuhd_1_1usrp_1_1multi__
> usrp.html#abdab1f6c3775a9071b15c9805f866486
>
> However, you'd have to extend the Gnu Radio multi_usrp "wrapper" (in
> gr-uhd in the main Gnu Radio codebase) to provide access to set_rx_agc().
>
> Note that in many cases, hardware AGC doesn't really work the way you'd
> like it to, since its "world view" may be very very different than the view
>   of your particular application.
>
>
>
>
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Re: [Discuss-gnuradio] Accessing the ADI registers on B200mini

[Marcus D. Leech]

On 03/20/2018 03:27 PM, Firdavs Pulat wrote:

Hi Marcus,

Could you please elaborate on the "extend the Gnu Radio multi_usrp" 
part? Maybe you could point me to some examples one how to set these 
(I assume others must have played around with them since it's so 
essential), or documentation on how that's done? I'm just not sure 
where/how in the usrp_source impl source code I would set them. I have 
been looking online, but haven't found anything of use yet.


Thank you!

In the Gnu Radio source code, in gr_uhd/usrp_source_impl.cc

If you look at any of the setter functions for various device 
parameters, you'd pattern your call to set_rx_agc() after one of those.  
The lowest-impact
  way to do it would be to "hijack" the existing gain-setting function, 
and have it look for "magic" gain value that then turns on hardware AGC

  via the set_rx_agc() function.

In reality, very few applications use the hardware AGC in the chip, 
which is one of the reasons that it hasn't yet been "mapped" into the GR

  API wrapper.





On Thu, Mar 8, 2018 at 10:58 AM, Marcus D. Leech > wrote:


On 03/08/2018 10:43 AM, Firdavs Pulat wrote:

Hi all,

Are there APIs as part of gnuradio that give access to the low
level ADI registers (to both probe, and set)? For instance,
I'm trying to see if the AGC is currently turned on on
B200mini, and if it's, what kind of mode it is on (e.g., slow
or fast). Looking at it the USRP manual online, I see
functions like set_agc, set_agc_mode, etc. I just don't have
any idea how/where to actually use/set these. Could anyone
please help me out?

Thanks!


No need to tinker with ADI registers.

The multi_usrp API provides access to a set_rx_agc function:


https://files.ettus.com/manual/classuhd_1_1usrp_1_1multi__usrp.html#abdab1f6c3775a9071b15c9805f866486



However, you'd have to extend the Gnu Radio multi_usrp "wrapper"
(in gr-uhd in the main Gnu Radio codebase) to provide access to
set_rx_agc().

Note that in many cases, hardware AGC doesn't really work the way
you'd like it to, since its "world view" may be very very
different than the view
  of your particular application.




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Re: [Discuss-gnuradio] Callback Function in Blocks for C++

[Luis Felipe Albarracin Sanchez]

Thanks both of you for the help,

I am checking the example in the throttle block and also the swig part, i
will let you know if i have further questions.

Kind regards.

On Tue, Mar 20, 2018 at 1:12 PM, Michael Dickens 
wrote:

> Hi Luis - You also have to make sure the function is passed through from
> C++ to Python via SWIG, which means that it must be in the public header in
> the OOT, not just the private header. Hope this helps! - MLD
>
> On Tue, Mar 20, 2018, at 12:40 PM, Luis Felipe Albarracin Sanchez wrote:
>
> Hello Everyone,
> I am trying to build a new block from scratch, that allows me to change
> parameter values while the flowgraph is running.
>
> I have found that for the .XML code i must use:
>
> "Function"($XXX)
>
> My question is, in the c++ code , besides creating the function and
> applying values to the parameter, do i need to do something else so the
> callback work?
>
> Thanks for the response.
>
> *___*
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>
>


-- 
Eng. Luis Felipe Albarracin
PMP
CCNA/CCDA/CCNP/CCDP/CCIP
ITIL v3 Foundation
Msc. Telematics / MBA
"Die Grenzen meiner Sprache bedeuten die Grenzen meiner Welt"
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Re: [Discuss-gnuradio] FSK transmitter tutorial

[Ron Economos]

I have a RTTY flow graph that you may find useful as a starting point. 
It's transmit only (I was just using it to test the RTTY decoder on the 
ICOM IC-7300 ham transceiver).


http://www.w6rz.net/rtty.grc

And a program to generate a baudot test file from a text file.

http://www.w6rz.net/baudot.c

Ron

On 03/20/2018 04:48 AM, Murray Thomson wrote:

Hi,

I would like to build an FSK modulator/demodulator. I'm using file 
sink/sources for the moment. I need to be able to specify the two 
frequencies, baud rate and sample rate (ideally at runtime).
I started with the gr-tutorial for qpsk, hoping to replace the 
modulation/demodulation with gfsk blocks, but I didn't get the result 
I was hoping for. I don't fully understand the gfsk module or how to 
change the frequencies after the modulation. I tried the fsk burst 
modem example, but it's not what I want. I would rather not use PDUs 
and I don't want to transmit in bursts.
 I would really appreciate if someone could point me to a tutorial or 
example on this. These are the resources I have read so far:


https://github.com/gnuradio/gr-tutorial/blob/master/examples/tutorial7/mpsk_stage6.grc
https://nccgroup.github.io/RFTM/fsk_transmitter.html
https://www.reddit.com/r/GNURadio/comments/3u5zp2/gnu_radio_gfsk_modulation_rate_deviation/
http://www.indigresso.com/wiki/doku.php?id=opentag:radios:testing_with_gnuradio
https://oshearesearch.com/index.php/2015/05/31/building-a-burst-fsk-modem-in-gnu-radio-with-message-lambda-blocks-and-eventstream/

Many thanks,
Murray





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