[Discuss-gnuradio] gr-lte : itemsize mismatch:

[Rafik ZITOUNI]

Dear all,

I tried to run the lte_top_block_siso.grc and I got this error :

/gr/runtime_swig.py", line 4574, in primitive_connect
return _runtime_swig.top_block_sptr_primitive_connect(self, *args)
ValueError: itemsize mismatch: Channel Estimator0:0 using 576, PBCH
Decoder0:1 using 480

Please could you have any idea how to fix this issue?

Best,

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[Discuss-gnuradio] Internship proposal

[Rafik ZITOUNI]

Hi everyone,

If you are passionate by radio communications and software programming on
GNU Radio, VEDECOM (Versailles, France) institute propose a student
internship of 6 months on radio access technologies for 5G adapted to the
automotive communications.


VEDECOM is an Institute for Energy Transition (ITE) established as part of
the French government’s forward-looking investment plan. It is also a part
of the French autonomous vehicle plan and was recently added to
‘Eco-mobility’, one of nine ‘solutions for the industry of the future’ that
form part of a government scheme called ‘Nouvelle France Industrielle’,
designed to reinvigorate the country’s industry. VEDECOM is a
partnership-based foundation belonging to the University of Versailles
Saint-Quentin-en-Yvelines, France.


The duration of the internship is *6 months*.

Monthly net salary*: 700€* per month

Date of beginning:  *as soon as possible *

Candidates are invited to contact *Rafik Zitouni*


firstname.lastn...@vedecom.fr


Best,
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[Discuss-gnuradio] Error with wifi_tx and wifi_transceiver

[Rafik ZITOUNI]

Hi,

I am using gnuradio in a second machine where I had installed gnuradio
version 3.7.12git-126-g37d373ac.

I tried to run wifi_tx and wifi_transceiver and I obtained the following
error:

tb = top_block_cls()
  File "/home/rafik/Workspace/gr-ieee802-11-next/examples/wifi_tx.py", line
153, in __init__
sensitivity=0.56,
  File "/home/rafik/.grc_gnuradio/wifi_phy_hier.py", line 81, in __init__
self.msg_connect((self.ieee802_11_decode_mac_0, 'out'), (self,
'mac_out'))
  File "/opt/usr/lib/python2.7/dist-packages/gnuradio/gr/hier_block2.py",
line 59, in wrappe
d
func(self, src.to_basic_block(), srcport, dst.to_basic_block(), dstport)
  File "/opt/usr/lib/python2.7/dist-packages/gnuradio/gr/hier_block2.py",
line 131, in msg_c
onnect
self.primitive_msg_connect(*args)
  File "/opt/usr/lib/python2.7/dist-packages/gnuradio/gr/runtime_swig.py",
line 3043, in pri
mitive_msg_connect
return _runtime_swig.hier_block2_sptr_primitive_msg_connect(self, *args)
RuntimeError: invalid msg port in connect() or disconnect()


Do you have an idea how to fix this error.

Best,

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Re: [Discuss-gnuradio] GNU Radio debug with GDB

[Rafik ZITOUNI]

Thanks you Marcus and Cinaed for your answer,

I removed libc6-dbg from my ubuntu 14.04 and it is working now. I just give
the cc source code and after that added my breakpoints and debug works
fine.

For thread info, Yes I doing it on ddd, with a graphical tool seeing the
threads' numbers.

Best regards,

Rafik,





2017-07-18 1:10 GMT+02:00 Marcus Müller <marcus.muel...@ettus.com>:

> ... and that's not a problem per se. Anyway, this is a syscall, and it's
> unlikely that there's a problem *within* your operating system.
>
> So, the rest of the backtrace where this is from is very likely more
> relevant.
>
> Also, poll() might indicate this is a more or less idle thread; use
> `info threads` to see the other threads of your process; use `thread
> NUMBER` to switch between them.
>
> Best regards,
>
> Marcus
>
>
> On 17.07.2017 22:49, Cinaed Simson wrote:
> > On 07/17/2017 09:28 AM, Rafik ZITOUNI wrote:
> >> Dear all,
> >>
> >> I have an issue that appears when I'm running gdb.
> >>
> >> I obtained the following message.
> >>
> >> 0x7fcb038c6c5d in poll () at ../sysdeps/unix/syscall-template.S:81
> >> 81  ../sysdeps/unix/syscall-template.S: No such file or directory.
> >>
> >>
> >> Could you have any idea how to fix this issue?
> > Typically it means you don't have source code to a library.
> >
> > -- Cinaed
> >
> >
> >> Best,
> >> --
> >> **<http://www.ece.fr/>Rafik
> >>
> >>
> >>
> >> ___
> >> Discuss-gnuradio mailing list
> >> Discuss-gnuradio@gnu.org
> >> https://lists.gnu.org/mailman/listinfo/discuss-gnuradio
> >>
> >
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>
>
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>



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[Discuss-gnuradio] GNU Radio debug with GDB

[Rafik ZITOUNI]

Dear all,

I have an issue that appears when I'm running gdb.

I obtained the following message.

0x7fcb038c6c5d in poll () at ../sysdeps/unix/syscall-template.S:81
81  ../sysdeps/unix/syscall-template.S: No such file or directory.


Could you have any idea how to fix this issue?

Best,
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Re: [Discuss-gnuradio] Chunks to symbols with 16 QAM modulation

[Rafik ZITOUNI]

Dear Marcus,

Thanks for your answer and the precious complementary information. I
conclude that an implementation of QAM16's costas loop is more complicated
than the existing one, i.e  MPK receiver.

I am trying to reuse some existing implementation with 16QAM in order to
obtain something with my flowgraphs.

Best regards,



2017-07-17 14:25 GMT+02:00 Marcus Müller <muel...@kit.edu>:

> Hi Rafik,
>
> I should have been a little more constructive in my last email:
> It's not inherently impossible to correct phase of a QAM reception using a
> costas loop – it's just that the GNU Radio costas loop block makes
> assumptions that break down for 16QAM:
>
>- The Costas loop is a phase-only correction mechanism. Now, there's
>12 different phases in a 16QAM:
>[image: Phases of QAM]
>Thus, all the Phase-locking Costas could do is correct things so that
>you find the 12 possible phase values again
>- Problem: While after a PSK-correcting Costas loop, you only have to
>correct the phase ambiguity by rotating until the right symbol shows up at
>the right position, now there's possibly one or two symbols, so your
>ambiguity resolution gets a whole lot less fun
>- The angles (¼π, ¾π, 5̸4π and 7̸4π [blue and green lines], ±atan(±⅓)
>[orange and red] and π/2±atan(±⅓) [violet and brown]) aren't equally
>distributed around the circle – which means that the costas-typical
>assumption of linear, uniform error-over-angle function breaks down. This
>is per se not catastrophical, but will actively break your system in
>low-SNR situation. You'd have to build a costas loop with a phase error
>detector (PED) that has a feeling for whether the current symbol is on a
>diagonal or not, and adjusts the error estimate appropriately
>- The ¼π, ¾π, 5̸4π and 7̸4π angles each are twice as likely to occur
>than any of the other 8 phases (simply because there's two constellation
>points on each of these phases, vs one for the rest). That means that you
>might want to adjust your decision regions for a self-built PED 
> accordingly.
>
> The GNU Radio Costas Loop supports none of that. It's really meant for
> lower-order PSK constellations, and doesn't have the flexibility to address
> inequal phase decision boundaries etc. Really, Costas Loops are usually
> *not* used to recover phase of non-PSK modulations, as far as I (limited
> experience with QAM receivers) can tell.
>
> So, generally, if you can do timing recovery (and that might be possible,
> e.g. with a Polyphase Filterbank Clock Recovery approach), you should be
> able to see the constellation diagram. However, that will be rotated, and
> possibly also still slowly continue to rotate, depending on how good your
> timing recovery works. As I tried to hint at above, it's not trivial to
> design a phase recovery for true QAM modulations – in fact, the need to do
> that is, in practice, often avoided by having sufficient channel state info
> from somewhere else – e.g. by having a known preamble that can be used to
> derotate.
>
> Phase sync, like any sync, is always pretty application-specific, and it's
> not inherently easy to say, "yeah, that's the optimal algorithm" for any
> given case. You'll often find something like a receiver getting the initial
> phase estimate by correlating the post-timing-recovery stream to a known
> sequence, and then either using a phase error loop with a small bandwidth,
> assuming that phase jumps will never be large enough that you end up
> jumping the minimum phase distance between constellation points, or looking
> for periodically inserted pilot symbols and updating their internal phase
> tracking from these.
>
> Personally, I kind of still consider the Costas Loop a concept rooted in
> analog signal processing (though it definitely works good in digital
> domain, too) with the error signals etc actually being analog voltages
> being fed back to analog summing amplifiers and so on. That makes it easy
> (ok, easier) for me to visualize how phase stabilization for PSK-type
> modulations works. If I have to imagine I'd have to synchronize a quantized
> QAM with such a thing optimally, I'd have a hard time describing what the
> analog error estimator and analog loop filter should look like. In digital
> domain, we get all the "logic" coming cheap, so, yeah, why not have a few %
> of symbols being used for phase recovery and skip the phase error loop – we
> can double-use them to estimate more of the channel than just the phase, so
> that's not such a bad deal, usually. Again, this is all very
> application-specific!
> Best regards,
> Marcus
>
>
> On 07/17/2017 12:56 PM, Rafik ZITOUNI wrote:
>
> Thanks Marcus,
>
> So

Re: [Discuss-gnuradio] Chunks to symbols with 16 QAM modulation

[Rafik ZITOUNI]

Thanks Marcus,

So, how can I see my constellation points with 16 QAM receiver ?

Regards,



2017-07-17 12:26 GMT+02:00 Marcus Müller <muel...@kit.edu>:

> No.
>
> That's not going to work out, mathematically.
>
> Best regards,
>
> Marcus
>
> On 07/17/2017 10:29 AM, Rafik ZITOUNI wrote:
>
> Dear Cinaed,
>
> The costas loop works only with BPSK, QPSK and 8PSK.
>
> Is it possible to change the actual costas loop and add the 16 QAM.
>
> Best regards,
>
>
>
> 2017-07-14 0:46 GMT+02:00 Cinaed Simson <cinaed.sim...@gmail.com>:
>
>> On 07/13/2017 06:16 AM, Rafik ZITOUNI wrote:
>> > Dear Cinaed,
>> >
>> > But how to see the constellations of my received symbols since
>> > constellation receiver and constellation decoder have a byte as an
>> output.
>> >
>> > Is it possible to have a costas loop for QAM 16?
>>
>> I use the Polyphase Clock Sync.
>>
>> In the tutorial 7, they use a channel model
>>
>>  Const. Demod -> Channel Model-> Polyphase Clock -> CMA Equalizer ->
>> Costa Loop -> Demodulator
>>
>> and put the Constellation Sink on the output of the Costa Loop.
>>
>> -- Cinaed
>>
>> >
>> > Thanks,
>> >
>> > 2017-07-13 1:30 GMT+02:00 Cinaed Simson <cinaed.sim...@gmail.com
>> > <mailto:cinaed.sim...@gmail.com>>:
>> >
>> > On 07/12/2017 09:55 AM, Rafik ZITOUNI wrote:
>> > > Dear Cinaed,
>> > >
>> > > Thanks for your answer.
>> > >
>> > > I tried with my Tx and it works fine with a constellation, but
>> with my
>> > > receiver symbols or  constellation_decoder, digital.qam_16()[1]
>> gives me
>> > > an error.
>> >
>> > I'm using the Constellation Modulator/Constellation Decoder pair
>> and the
>> > Constellation Object with Type=Variable Constellation.
>> >
>> > The same object is used for both the Constellation Modulator and the
>> > Constellation Decoder.
>> >
>> > When I look inside the Constellation Decoder there's nothing to
>> > configure.
>> >
>> > Maybe you're doing things differently.
>> >
>> > -- Cinaed
>> >
>> > >
>> > > line 164, in __init__
>> > > self.digital_constellation_decoder_cb_0_0 =
>> > > digital.constellation_decoder_cb(digital.qam_16()[1])
>> > >
>> > > Best,
>> > >
>> > >
>> > >
>> > >
>> > > 2017-07-12 2:26 GMT+02:00 Cinaed Simson <cinaed.sim...@gmail.com
>> <mailto:cinaed.sim...@gmail.com>
>> > > <mailto:cinaed.sim...@gmail.com <mailto:cinaed.sim...@gmail.com
>> >>>:
>> > >
>> > > On 07/11/2017 05:13 AM, Rafik ZITOUNI wrote:
>> > > > Dear gnuradio users,
>> > > >
>> > > > I am trying to use digital_chunks_to_symbols to reconstruct
>> block by
>> > > > block my QAM modulator.
>> > > >
>> > > > Please could you give me an idea how to set the
>> constellation points in
>> > > > Symbol Table field?  I can do it with BPSK, QPSK and 8PSK
>> using
>> > > > constellation[0].points, constellation[1].points and
>> > > > constellation[2].points, but how can I do it with 16 QAM ?
>> > >
>> > > Try
>> > >
>> > >  Symbols:digital.qam_16()[1]
>> > >  Constellations: digital.qam_16()[0]
>> > >
>> > > -- Cinaed
>> > >
>> > >
>> > > >
>> > > > For my 16 QAM receiver, could you please tell me if it's
>> possible to
>> > > > have a constellation points view?
>> > > >
>> > > > Best,
>> > > >
>> > > > --
>> > > > **<http://www.ece.fr/>Rafik
>> > > >
>> > > >
>> > > >
>> > > > ___
>> > > > Discuss-gnuradio mailing list
>> > > > Discuss-gnuradio@gnu.org <mailto:Discuss-gnuradio@gnu.org>
>> &

Re: [Discuss-gnuradio] Chunks to symbols with 16 QAM modulation

[Rafik ZITOUNI]

Dear Cinaed,

The costas loop works only with BPSK, QPSK and 8PSK.

Is it possible to change the actual costas loop and add the 16 QAM.

Best regards,



2017-07-14 0:46 GMT+02:00 Cinaed Simson <cinaed.sim...@gmail.com>:

> On 07/13/2017 06:16 AM, Rafik ZITOUNI wrote:
> > Dear Cinaed,
> >
> > But how to see the constellations of my received symbols since
> > constellation receiver and constellation decoder have a byte as an
> output.
> >
> > Is it possible to have a costas loop for QAM 16?
>
> I use the Polyphase Clock Sync.
>
> In the tutorial 7, they use a channel model
>
>  Const. Demod -> Channel Model-> Polyphase Clock -> CMA Equalizer ->
> Costa Loop -> Demodulator
>
> and put the Constellation Sink on the output of the Costa Loop.
>
> -- Cinaed
>
> >
> > Thanks,
> >
> > 2017-07-13 1:30 GMT+02:00 Cinaed Simson <cinaed.sim...@gmail.com
> > <mailto:cinaed.sim...@gmail.com>>:
> >
> > On 07/12/2017 09:55 AM, Rafik ZITOUNI wrote:
> > > Dear Cinaed,
> > >
> > > Thanks for your answer.
> > >
> > > I tried with my Tx and it works fine with a constellation, but
> with my
> > > receiver symbols or  constellation_decoder, digital.qam_16()[1]
> gives me
> > > an error.
> >
> > I'm using the Constellation Modulator/Constellation Decoder pair and
> the
> > Constellation Object with Type=Variable Constellation.
> >
> > The same object is used for both the Constellation Modulator and the
> > Constellation Decoder.
> >
> > When I look inside the Constellation Decoder there's nothing to
> > configure.
> >
> > Maybe you're doing things differently.
> >
> > -- Cinaed
> >
> > >
> > > line 164, in __init__
> > > self.digital_constellation_decoder_cb_0_0 =
> > > digital.constellation_decoder_cb(digital.qam_16()[1])
> > >
> > > Best,
> > >
> > >
> > >
> > >
> > > 2017-07-12 2:26 GMT+02:00 Cinaed Simson <cinaed.sim...@gmail.com
> <mailto:cinaed.sim...@gmail.com>
> > > <mailto:cinaed.sim...@gmail.com <mailto:cinaed.sim...@gmail.com
> >>>:
> > >
> > > On 07/11/2017 05:13 AM, Rafik ZITOUNI wrote:
> > > > Dear gnuradio users,
> > > >
> > > > I am trying to use digital_chunks_to_symbols to reconstruct
> block by
> > > > block my QAM modulator.
> > > >
> > > > Please could you give me an idea how to set the
> constellation points in
> > > > Symbol Table field?  I can do it with BPSK, QPSK and 8PSK
> using
> > > > constellation[0].points, constellation[1].points and
> > > > constellation[2].points, but how can I do it with 16 QAM ?
> > >
> > > Try
> > >
> > >  Symbols:digital.qam_16()[1]
> > >  Constellations: digital.qam_16()[0]
> > >
> > > -- Cinaed
> > >
> > >
> > > >
> > > > For my 16 QAM receiver, could you please tell me if it's
> possible to
> > > > have a constellation points view?
> > > >
> > > > Best,
> > > >
> > > > --
> > > > **<http://www.ece.fr/>Rafik
> > > >
> > > >
> > > >
> > > > ___
> > > > Discuss-gnuradio mailing list
> > > > Discuss-gnuradio@gnu.org <mailto:Discuss-gnuradio@gnu.org>
> > <mailto:Discuss-gnuradio@gnu.org <mailto:Discuss-gnuradio@gnu.org>>
> > > > https://lists.gnu.org/mailman/listinfo/discuss-gnuradio
> > <https://lists.gnu.org/mailman/listinfo/discuss-gnuradio>
> > > <https://lists.gnu.org/mailman/listinfo/discuss-gnuradio
> > <https://lists.gnu.org/mailman/listinfo/discuss-gnuradio>>
> > > >
> > >
> > >
> > > ___
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> > <mailto:Discuss-gnuradio@gnu.org <mailto:Discuss-gnuradio@gnu.org>>
> > > https://lists.gnu.org/mailman/listinfo/discuss-gnuradio
> > <https://lists.gnu.org/mailman/listinfo/discuss-gnuradio>
> > > <https://lists.gnu.org/mailman/listinfo/discuss-gnuradio
> > <https://lists.gnu.org/mailman/listinfo/discuss-gnuradio>>
> > >
> > >
> > >
> > >
> > > --
> > > **<http://www.ece.fr/>Rafik
> > >
> >
> >
> >
> >
> > --
> > **<http://www.ece.fr/>Rafik
> >
>
>


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Re: [Discuss-gnuradio] Chunks to symbols with 16 QAM modulation

[Rafik ZITOUNI]

Dear Cinaed,

But how to see the constellations of my received symbols since
constellation receiver and constellation decoder have a byte as an output.

Is it possible to have a costas loop for QAM 16?

Thanks,

2017-07-13 1:30 GMT+02:00 Cinaed Simson <cinaed.sim...@gmail.com>:

> On 07/12/2017 09:55 AM, Rafik ZITOUNI wrote:
> > Dear Cinaed,
> >
> > Thanks for your answer.
> >
> > I tried with my Tx and it works fine with a constellation, but with my
> > receiver symbols or  constellation_decoder, digital.qam_16()[1] gives me
> > an error.
>
> I'm using the Constellation Modulator/Constellation Decoder pair and the
> Constellation Object with Type=Variable Constellation.
>
> The same object is used for both the Constellation Modulator and the
> Constellation Decoder.
>
> When I look inside the Constellation Decoder there's nothing to configure.
>
> Maybe you're doing things differently.
>
> -- Cinaed
>
> >
> > line 164, in __init__
> > self.digital_constellation_decoder_cb_0_0 =
> > digital.constellation_decoder_cb(digital.qam_16()[1])
> >
> > Best,
> >
> >
> >
> >
> > 2017-07-12 2:26 GMT+02:00 Cinaed Simson <cinaed.sim...@gmail.com
> > <mailto:cinaed.sim...@gmail.com>>:
> >
> > On 07/11/2017 05:13 AM, Rafik ZITOUNI wrote:
> > > Dear gnuradio users,
> > >
> > > I am trying to use digital_chunks_to_symbols to reconstruct block
> by
> > > block my QAM modulator.
> > >
> > > Please could you give me an idea how to set the constellation
> points in
> > > Symbol Table field?  I can do it with BPSK, QPSK and 8PSK using
> > > constellation[0].points, constellation[1].points and
> > > constellation[2].points, but how can I do it with 16 QAM ?
> >
> > Try
> >
> >  Symbols:digital.qam_16()[1]
> >  Constellations: digital.qam_16()[0]
> >
> > -- Cinaed
> >
> >
> > >
> > > For my 16 QAM receiver, could you please tell me if it's possible
> to
> > > have a constellation points view?
> > >
> > > Best,
> > >
> > > --
> > > **<http://www.ece.fr/>Rafik
> > >
> > >
> > >
> > > ___
> > > Discuss-gnuradio mailing list
> > > Discuss-gnuradio@gnu.org <mailto:Discuss-gnuradio@gnu.org>
> > > https://lists.gnu.org/mailman/listinfo/discuss-gnuradio
> > <https://lists.gnu.org/mailman/listinfo/discuss-gnuradio>
> > >
> >
> >
> > ___
> > Discuss-gnuradio mailing list
> > Discuss-gnuradio@gnu.org <mailto:Discuss-gnuradio@gnu.org>
> > https://lists.gnu.org/mailman/listinfo/discuss-gnuradio
> > <https://lists.gnu.org/mailman/listinfo/discuss-gnuradio>
> >
> >
> >
> >
> > --
> > **<http://www.ece.fr/>Rafik
> >
>
>


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Re: [Discuss-gnuradio] Chunks to symbols with 16 QAM modulation

[Rafik ZITOUNI]

Dear Cinaed,

Thanks for your answer.

I tried with my Tx and it works fine with a constellation, but with my
receiver symbols or  constellation_decoder, digital.qam_16()[1] gives me an
error.

line 164, in __init__
self.digital_constellation_decoder_cb_0_0 =
digital.constellation_decoder_cb(digital.qam_16()[1])

Best,




2017-07-12 2:26 GMT+02:00 Cinaed Simson <cinaed.sim...@gmail.com>:

> On 07/11/2017 05:13 AM, Rafik ZITOUNI wrote:
> > Dear gnuradio users,
> >
> > I am trying to use digital_chunks_to_symbols to reconstruct block by
> > block my QAM modulator.
> >
> > Please could you give me an idea how to set the constellation points in
> > Symbol Table field?  I can do it with BPSK, QPSK and 8PSK using
> > constellation[0].points, constellation[1].points and
> > constellation[2].points, but how can I do it with 16 QAM ?
>
> Try
>
>  Symbols:digital.qam_16()[1]
>  Constellations: digital.qam_16()[0]
>
> -- Cinaed
>
>
> >
> > For my 16 QAM receiver, could you please tell me if it's possible to
> > have a constellation points view?
> >
> > Best,
> >
> > --
> > **<http://www.ece.fr/>Rafik
> >
> >
> >
> > ___
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[Discuss-gnuradio] Chunks to symbols with 16 QAM modulation

[Rafik ZITOUNI]

Dear gnuradio users,

I am trying to use digital_chunks_to_symbols to reconstruct block by block
my QAM modulator.

Please could you give me an idea how to set the constellation points in
Symbol Table field?  I can do it with BPSK, QPSK and 8PSK using
constellation[0].points, constellation[1].points and
constellation[2].points, but how can I do it with 16 QAM ?

For my 16 QAM receiver, could you please tell me if it's possible to have a
constellation points view?

Best,

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Re: [Discuss-gnuradio] Good SNR despite rotating constellation

[Rafik ZITOUNI]

Thank you so match for your detailed and accurate answers.

I received a second answer from Phil Frost in which he explained my result.
So now i am doing same thing with QPSK and 8PSK.


Cheers,


2017-07-04 14:25 GMT+02:00 Phil Frost <ind...@bitglue.com>:

> On Tue, Jul 4, 2017 at 6:30 AM Rafik ZITOUNI <rzito...@gmail.com> wrote:
>
>> Could you give me an explanation how it was possible to obtain a good snr
>> and ber with a wrong constellation with  good SNR and BER?
>>
>
> for BPSK the value of the bit is determined only by examining the sign of
> the real part. There will be errors only when the cluster of points
> approaches the imaginary axis, where the sign of the real point changes. If
> the frequency offset it small (it rotates slowly) and the SNR high, then
> for most rotations there will be negligible errors.
>
> In practice you will probably have great difficulty tuning the receiver
> accurately enough for this to work. Furthermore, doppler shift in the
> channel may make the frequency change over time. Thus, the need for the
> Costas loop or some other frequency synchronization.
>
> Alternately, you can compare the phase of the current signal to the
> previous symbol: https://en.wikipedia.org/wiki/
> Phase-shift_keying#Demodulation
>



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Re: [Discuss-gnuradio] BER & SNR

[Rafik ZITOUNI]

Thank you so match for your detailed and accurate answers.

I received a second answer from Phil Frost in which he explained my result.
So now i am doing same thing with QPSK and 8PSK.


Cheers,


2017-07-04 14:25 GMT+02:00 Phil Frost <ind...@bitglue.com>:

> On Tue, Jul 4, 2017 at 6:30 AM Rafik ZITOUNI <rzito...@gmail.com> wrote:
>
>> Could you give me an explanation how it was possible to obtain a good snr
>> and ber with a wrong constellation with  good SNR and BER?
>>
>
> for BPSK the value of the bit is determined only by examining the sign of
> the real part. There will be errors only when the cluster of points
> approaches the imaginary axis, where the sign of the real point changes. If
> the frequency offset it small (it rotates slowly) and the SNR high, then
> for most rotations there will be negligible errors.
>
> In practice you will probably have great difficulty tuning the receiver
> accurately enough for this to work. Furthermore, doppler shift in the
> channel may make the frequency change over time. Thus, the need for the
> Costas loop or some other frequency synchronization.
>
> Alternately, you can compare the phase of the current signal to the
> previous symbol: https://en.wikipedia.org/wiki/Phase-shift_keying#
> Demodulation
>



for BPSK the value of the bit is determined only by examining the sign of
the real part. There will be errors only when the cluster of points
approaches the imaginary axis, where the sign of the real point changes. If
the frequency offset it small (it rotates slowly) and the SNR high, then
for most rotations there will be negligible errors.

In practice you will probably have great difficulty tuning the receiver
accurately enough for this to work. Furthermore, doppler shift in the
channel may make the frequency change over time. Thus, the need for the
Costas loop or some other frequency synchronization.

Alternately, you can compare the phase of the current signal to the
previous symbol: https://en.wikipedia.org/wiki/Phase-shift_keying#
Demodulation


2017-07-04 12:48 GMT+02:00 Marcus Müller <marcus.muel...@ettus.com>:

> BER is an observation, a count, not an estimation – it only makes sense to
> talk about a Bit Error Rate (BER) after a complete physical layer receiver,
> i.e. at the bit level. You can estimate the BER of a whole system if you
> know how it reacts to noise – but that's typically not what you do.
> Instead, you just simulate with various noise/distortion levels, measure
> for each of these and write down the number of wrong bits. A good receiver
> will make more of a noisy signal (lower BER) than a bad receiver for the
> same modulation. So, BER depends on your receiver implementation.
>
> SNR, on the other hand, the Signal-to-noise-ratio, is not something that
> depends on your implementation – it's really just the ratio of Signal power
> to noise power. Since we're looking at a noise reception, one can only
> write an estimator for these powers – and thus, SNR is a measure relative
> to a mathematical model of your reception, and not something that indicated
> demodulability. It's very important to say *where* in the signal chain
> you look at the SNR – is it directly at the antenna? After mixing to
> baseband? After filtering to a channel bandwidth? It's equally important to
> explicitly specify what you consider signal and what you consider noise
> power – for example, one might say "OK, after my timing recovery, I still
> have a bit of phase offset, but that's OK, I just declare the difference
> between perfect constellation point and actual recovered point "noise" and
> be done with it". That's a very practical thing to look at – and, indeed,
> for the decider, which has to convert complex numbers to bits, it just
> looks like a random addition to the perfect signal, but that power didn't
> come in as noise power – it's just an error we introduced by not being able
> to perfectly synchronize.
>
> As another example, if you take any signal, and shift it in frequency,
> then that doesn't change its power at all! So, a reception with a terribly
> bad frequency offset still has the same SNR as a perfectly synchronized
> one. UNLESS, that is, that you declare the phase offset between recovered
> symbols and perfect constellation points "noise".
>
> Now, depending on what you declare to be noise and what you declare to be
> signal, you'd define different SNR estimators. I constantly repeat this (I
> don't mind, someone has to):
>
> *There's no single "right" SNR estimator. Everything depends on what you
> define to be noise and what you define to be signal. One man's noise is
> another man's signal.*
>
> Coming back to your original question:
> > How Is it possible to get a good 

Re: [Discuss-gnuradio] BER & SNR

[Rafik ZITOUNI]

My question is:

How Is it possible to get a good estimation of the BER without a costas
loop?




2017-07-04 11:39 GMT+02:00 Marcus Müller <marcus.muel...@ettus.com>:

> You're still not explaining what your question is – I really don't know
> what to answer.
>
> What is wrong?
>
> On 07/04/2017 11:31 AM, Rafik ZITOUNI wrote:
>
> Sorry I missed to add the flow graph.
> Here is attached.
>
> 2017-07-04 11:29 GMT+02:00 Rafik ZITOUNI <rzito...@gmail.com>:
>
>> Marcus,
>>
>> You find attached my flow graph with  Tx and Rx. I know that it is not
>> recommended to have TX and RX in the same flow graph but i did it just to
>> obtain one view for my Tx and Rx.
>>
>> Thanks,
>>
>> 2017-07-04 11:23 GMT+02:00 Marcus Müller <marcus.muel...@ettus.com>:
>>
>>> Dear Rafik,
>>>
>>> I think we're approaching this from the wrong side: I don't think that I
>>> should be explaining why you get a good BER and SNR estimate, it is you who
>>> should explain why you're expecting something different, and then we can
>>> discuss! I'm not quite sure what I could be explaining at this point :)
>>>
>>> Best regards,
>>>
>>> Marcus
>>>
>>> On 07/04/2017 11:20 AM, Rafik ZITOUNI wrote:
>>>
>>> Thank you Marcus for your answer !
>>>
>>> My BER and SNR are calculated and obtained using MPSK SNR Estimator
>>> Probe and Error Rate blocks. I obtained  two points, which rotate in the qt
>>> gui constellation sink despite the BER and SNR have been obtained as
>>> expected. Could you give me an explanation how it was possible to obtain a
>>> good snr and ber with a wrong constellation with  good SNR and BER?
>>>
>>> I found the  presentation of Tom Rondeau useful, since he explained the
>>> function of the costas loop block.  https://static.squares
>>> pace.com/static/543ae9afe4b0c3b808d72acd/543aee1fe4b09162d08
>>> 633fc/543aee1fe4b09162d0863402/1392309732018/mpsk.pdf
>>>
>>>
>>> This morning I add a Costas loop after a Polyphase Clock Syncronisation
>>> block, and it s going well. You find attached a screenshot of my
>>> constellation for a DBPSK of my receiver/transmitter. I propose to add
>>> a grc to gnuradio/gr-digital for MPSK since grc is more easy to understand
>>> than python source code.
>>>
>>>
>>> Now I am trying to send and receive data files such as videos or images
>>> (bmp). Do you have an example with a file exchange implemented in .py or
>>> grc?
>>>
>>> Best,
>>>
>>>
>>> 2017-07-04 9:44 GMT+02:00 Marcus Müller <marcus.muel...@ettus.com>:
>>>
>>>> Hi Rafik!
>>>>
>>>> So, what's wrong with the BER and the SNR estimate?
>>>>
>>>> Best regards,
>>>>
>>>> Marcus
>>>>
>>>> On 07/03/2017 11:29 PM, Rafik ZITOUNI wrote:
>>>>
>>>> Dear all,
>>>>
>>>> I translate the /gr-digital/examples/narrowband/digital_bert_tx.py and
>>>> the /gr-digital/examples/narrowband/digital_bert_rx.py python source
>>>> codes to GRC flow graphs. The objective is to get more graphical
>>>> possibilities with a GRC.  My flow graph gives a fine result of BER and SNR
>>>> for DBPSK modulation.
>>>> The problem is with the rotating points of my constellation. I think
>>>> that the rotation of my view comes from a lack of frequency
>>>> synchronization, but why I obtained a correct BER and SNR?
>>>>
>>>> You find attached to this message a constellation view obtained by my
>>>> flow graph.
>>>>
>>>> Please could you explain me this  result or give an advice to improve
>>>> the obtained result?
>>>>
>>>> Regards,
>>>>
>>>>
>>>> --
>>>> <http://www.ece.fr/>Rafik
>>>>
>>>>
>>>>
>>>> ___
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>>>> listinfo/discuss-gnuradio
>>>
>>> --
>>> <http://www.ece.fr/>Rafik
>>>
>>> --
>> <http://www.ece.fr/>Rafik
>>
> --
> <http://www.ece.fr/>Rafik
>
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Re: [Discuss-gnuradio] BER & SNR (was: Re: (no subject))

[Rafik ZITOUNI]

Marcus,

You find attached my flow graph with  Tx and Rx. I know that it is not
recommended to have TX and RX in the same flow graph but i did it just to
obtain one view for my Tx and Rx.

Thanks,

2017-07-04 11:23 GMT+02:00 Marcus Müller <marcus.muel...@ettus.com>:

> Dear Rafik,
>
> I think we're approaching this from the wrong side: I don't think that I
> should be explaining why you get a good BER and SNR estimate, it is you who
> should explain why you're expecting something different, and then we can
> discuss! I'm not quite sure what I could be explaining at this point :)
>
> Best regards,
>
> Marcus
>
> On 07/04/2017 11:20 AM, Rafik ZITOUNI wrote:
>
> Thank you Marcus for your answer !
>
> My BER and SNR are calculated and obtained using MPSK SNR Estimator Probe
> and Error Rate blocks. I obtained  two points, which rotate in the qt gui
> constellation sink despite the BER and SNR have been obtained as expected.
> Could you give me an explanation how it was possible to obtain a good snr
> and ber with a wrong constellation with  good SNR and BER?
>
> I found the  presentation of Tom Rondeau useful, since he explained the
> function of the costas loop block.  https://static.squares
> pace.com/static/543ae9afe4b0c3b808d72acd/543aee1fe4b09162d08
> 633fc/543aee1fe4b09162d0863402/1392309732018/mpsk.pdf
>
>
> This morning I add a Costas loop after a Polyphase Clock Syncronisation
> block, and it s going well. You find attached a screenshot of my
> constellation for a DBPSK of my receiver/transmitter. I propose to add a
> grc to gnuradio/gr-digital for MPSK since grc is more easy to understand
> than python source code.
>
>
> Now I am trying to send and receive data files such as videos or images
> (bmp). Do you have an example with a file exchange implemented in .py or
> grc?
>
> Best,
>
>
> 2017-07-04 9:44 GMT+02:00 Marcus Müller <marcus.muel...@ettus.com>:
>
>> Hi Rafik!
>>
>> So, what's wrong with the BER and the SNR estimate?
>>
>> Best regards,
>>
>> Marcus
>>
>> On 07/03/2017 11:29 PM, Rafik ZITOUNI wrote:
>>
>> Dear all,
>>
>> I translate the /gr-digital/examples/narrowband/digital_bert_tx.py and
>> the /gr-digital/examples/narrowband/digital_bert_rx.py python source
>> codes to GRC flow graphs. The objective is to get more graphical
>> possibilities with a GRC.  My flow graph gives a fine result of BER and SNR
>> for DBPSK modulation.
>> The problem is with the rotating points of my constellation. I think that
>> the rotation of my view comes from a lack of frequency synchronization, but
>> why I obtained a correct BER and SNR?
>>
>> You find attached to this message a constellation view obtained by my
>> flow graph.
>>
>> Please could you explain me this  result or give an advice to improve the
>> obtained result?
>>
>> Regards,
>>
>>
>> --
>> <http://www.ece.fr/>Rafik
>>
>>
>>
>> ___
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>> listinfo/discuss-gnuradio
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> --
> <http://www.ece.fr/>Rafik
>
>


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Re: [Discuss-gnuradio] (no subject)

[Rafik ZITOUNI]

Thank you Marcus for your answer !

My BER and SNR are calculated and obtained using MPSK SNR Estimator Probe
and Error Rate blocks. I obtained  two points, which rotate in the qt gui
constellation sink despite the BER and SNR have been obtained as expected.
Could you give me an explanation how it was possible to obtain a good snr
and ber with a wrong constellation with  good SNR and BER?

I found the  presentation of Tom Rondeau useful, since he explained the
function of the costas loop block.  https://static.squarespace.com/static/
543ae9afe4b0c3b808d72acd/543aee1fe4b09162d08633fc/543aee1fe4b09162d0863402/
1392309732018/mpsk.pdf


This morning I add a Costas loop after a Polyphase Clock Syncronisation
block, and it s going well. You find attached a screenshot of my
constellation for a DBPSK of my receiver/transmitter. I propose to add a
grc to gnuradio/gr-digital for MPSK since grc is more easy to understand
than python source code.


Now I am trying to send and receive data files such as videos or images
(bmp). Do you have an example with a file exchange implemented in .py or
grc?

Best,


2017-07-04 9:44 GMT+02:00 Marcus Müller <marcus.muel...@ettus.com>:

> Hi Rafik!
>
> So, what's wrong with the BER and the SNR estimate?
>
> Best regards,
>
> Marcus
>
> On 07/03/2017 11:29 PM, Rafik ZITOUNI wrote:
>
> Dear all,
>
> I translate the /gr-digital/examples/narrowband/digital_bert_tx.py and
> the /gr-digital/examples/narrowband/digital_bert_rx.py python source
> codes to GRC flow graphs. The objective is to get more graphical
> possibilities with a GRC.  My flow graph gives a fine result of BER and SNR
> for DBPSK modulation.
> The problem is with the rotating points of my constellation. I think that
> the rotation of my view comes from a lack of frequency synchronization, but
> why I obtained a correct BER and SNR?
>
> You find attached to this message a constellation view obtained by my flow
> graph.
>
> Please could you explain me this  result or give an advice to improve the
> obtained result?
>
> Regards,
>
>
> --
> <http://www.ece.fr/>Rafik
>
>
>
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[Discuss-gnuradio] (no subject)

[Rafik ZITOUNI]

Dear all,

I translate the /gr-digital/examples/narrowband/digital_bert_tx.py and the
/gr-digital/examples/narrowband/digital_bert_rx.py python source codes to
GRC flow graphs. The objective is to get more graphical possibilities with
a GRC.  My flow graph gives a fine result of BER and SNR for DBPSK
modulation.
The problem is with the rotating points of my constellation. I think that
the rotation of my view comes from a lack of frequency synchronization, but
why I obtained a correct BER and SNR?
[image: Images intégrées 1]
You find attached to this message a constellation view obtained by my flow
graph.

Please could you explain me this  result or give an advice to improve the
obtained result?

Regards,


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