Re: [Discuss-gnuradio] GnuRadio: Clock Recovery MM: imu out of bounds

[Marcus Müller]

Hi Michael,

so, this having sat on my "what the hell, I need to look at this" list
for the weekend:
I can't reproduce the behaviour, but that might simply have the cause of
me using white noise instead of your recording. Could you share that?

I have two hypotheses and one observation so far:
The observation is that in many places where we want to get the closest
int to a float, we use stuff like int imu= rint(mu*NSTEPS), which is
wrong in respect to the return value (double), the parameter type
(double) and in most cases also the side effects (rint is the version of
nearbyint that sets error flags, but we don't check them). We should use
something else; that's an overhaul of existing code that'll have to be
done another day.

So first hypothesis:
It's your signal that will suffice for us to reproduce the error. That's
the "good" case, because then one can actually inspect what goes wrong here.

Second hypothesis:
Based on above observation and VirtualBox' history of delicate floating
point bugs, this might get a bit more involved, especially since
floating point exception registers are involved, which historically were
hard to properly multithread/make ISR save; maybe the overhaul mentioned
above would solve the issue, though.

Best regards,
Marcus

On 21.08.2015 08:00, Michael B wrote:
> Hi Tom,
>
> Thanks for your help. I've adapted the sample rate of the result
> coming out of the low-pass filter now. However, if I decimate much
> further, my signal becomes a bit too weak I think.
> New chart:
> http://imgur.com/mbt288s,etHbYLT#0
>
> New result:
> http://imgur.com/mbt288s,etHbYLT#1
>
> Is this a better approach?
> The initial error still persists though.
>
> Regards
>
>
>
>
>  
>
>
> 
> From: mibo...@hotmail.com
> To: t...@trondeau.com
> Date: Thu, 20 Aug 2015 09:09:42 +0200
> CC: discuss-gnuradio@gnu.org
> Subject: Re: [Discuss-gnuradio] GnuRadio: Clock Recovery MM: imu out
> of bounds
>
> Hi Tom,
>
> Thanks for your answer. That's indeed something that I need to think
> about more. However, as I understand it, the samples per symbol rate
> is equal to (samp_rate / data_rate). My sample rate is 500k, and my
> data rate (i think) is only around 100 or 200. See this figure of my
> (cleaned) signal:
>
> http://imgur.com/8pNqCop
>
> You see that it takes approximately 10 ms to transmit one symbol. This
> means 100 symbols per second. As I have 500k samples per second, this
> means 5k samples per symbol, right?
>
> However, I have tried setting the samples per symbol to 4, just to
> try, and the 'out of bounds' error still persists.
>
> Regards,
> Michael
>
>  
>
>
> 
> From: t...@trondeau.com
> Date: Wed, 19 Aug 2015 09:41:19 -0400
> Subject: Re: [Discuss-gnuradio] GnuRadio: Clock Recovery MM: imu out
> of bounds
> To: mibo...@hotmail.com
> CC: discuss-gnuradio@gnu.org
>
> On Wed, Aug 19, 2015 at 2:51 AM, Michael B  <mailto:mibo...@hotmail.com>> wrote:
>
> I have created a flowgraph, based on an example of Michael Ossmann
> <https://github.com/mossmann/im-me/blob/master/garage/garage-decode.py>,
> which takes in a signal, and should output bits.
>
> I need to use the clock recovery MM block, which I do not fully
> understand yet. However, after reading some blogposts, I am quite
> sure that I can leave most of the settings default, except for the
> Omega one. Here's my flowgraph:
>
>
> http://imgur.com/pHRXnZu
>
> When running this flowgraph, it gives me the following error:
>
> /thread[thread-per-block[5]:]:
> mmse_fir_interpolator_ff: imu out of bounds./
>
>
>
> While searching, I stumbled upon this piece of code
> 
> <http://gnuradio.org/redmine/projects/gnuradio/repository/revisions/ce3d887a47b47cb2d5351e14066ceb56b2b3c892/entry/gr-filter/lib/mmse_fir_interpolator_ff.cc>
>  in
> the source of GnuRadio:
>
>
> /int imu = (int)rint(mu * NSTEPS);  
>   if((imu < 0) || (imu > NSTEPS)) {
> throw std::runtime_error("mmse_fir_interpolator_ff: imu out of
> bounds.\n");
>   }/
>
>
> So, I suspect it is not due to my Omega setting (which might be
> wrong, I have to play with that setting), but that it is due to my
> Mu setting, which is just the default (0.5). However, I understand
> that Mu needs to be between 0 and 1, so I do not really understand
> what the problem is. Anyone who does?
>
> Environment details:
>
>   * GNU Radio Compa

Re: [Discuss-gnuradio] GnuRadio: Clock Recovery MM: imu out of bounds

[Michael B]

Hi Tom,

Thanks for your help. I've adapted the sample rate of the result coming out of 
the low-pass filter now. However, if I decimate much further, my signal becomes 
a bit too weak I think. 
New chart:
http://imgur.com/mbt288s,etHbYLT#0

New result:
http://imgur.com/mbt288s,etHbYLT#1

Is this a better approach?
The initial error still persists though.

Regards




 


From: mibo...@hotmail.com
To: t...@trondeau.com
Date: Thu, 20 Aug 2015 09:09:42 +0200
CC: discuss-gnuradio@gnu.org
Subject: Re: [Discuss-gnuradio] GnuRadio: Clock Recovery MM: imu out of bounds




Hi Tom,

Thanks for your answer. That's indeed something that I need to think about 
more. However, as I understand it, the samples per symbol rate is equal to 
(samp_rate / data_rate). My sample rate is 500k, and my data rate (i think) is 
only around 100 or 200. See this figure of my (cleaned) signal:

http://imgur.com/8pNqCop

You see that it takes approximately 10 ms to transmit one symbol. This means 
100 symbols per second. As I have 500k samples per second, this means 5k 
samples per symbol, right?

However, I have tried setting the samples per symbol to 4, just to try, and the 
'out of bounds' error still persists.

Regards,
Michael

 


From: t...@trondeau.com
Date: Wed, 19 Aug 2015 09:41:19 -0400
Subject: Re: [Discuss-gnuradio] GnuRadio: Clock Recovery MM: imu out of bounds
To: mibo...@hotmail.com
CC: discuss-gnuradio@gnu.org

On Wed, Aug 19, 2015 at 2:51 AM, Michael B  wrote:






I have created a flowgraph, based on an example of Michael Ossmann, which takes 
in a signal, and should output bits.I need to use the clock recovery MM block, 
which I do not fully understand yet. However, after reading some blogposts, I 
am quite sure that I can leave most of the settings default, except for the 
Omega one. Here's my flowgraph:
http://imgur.com/pHRXnZu

When running this flowgraph, it gives me the following error:

thread[thread-per-block[5]:]: 
mmse_fir_interpolator_ff: imu out of bounds.



While searching, I stumbled upon this piece of code in the source of GnuRadio:


int imu = (int)rint(mu * NSTEPS);   
  if((imu < 0) || (imu > NSTEPS)) { 
throw std::runtime_error("mmse_fir_interpolator_ff: imu out of bounds.\n"); 
  }


So, I suspect it is not due to my Omega setting (which might be wrong, I have 
to play with that setting), but that it is due to my Mu setting, which is just 
the default (0.5). However, I understand that Mu needs to be between 0 and 1, 
so I do not really understand what the problem is. Anyone who does?Environment 
details:GNU Radio Companion 3.7.7.1Running a GNU Radio live DVD in a virtual 
machine (VirtualBox 4.2.12) on Windows 7.Using Volk machine: ssse3_64
  

Michael,
I don't have an answer, but I can say where you're doing something wrong. 
You're samples/symbol (samp_per_sym) is definitely /not/ 2.5k. That's a 
massively oversampled signal and can't be right. You need to think what's the 
sampling rate of the system? What's the symbol rate of my signal? That will 
tell you the samples/symbol you need. It should small, like 2 or 4.
Tom
  

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Re: [Discuss-gnuradio] GnuRadio: Clock Recovery MM: imu out of bounds

[Tom Rondeau]

On Thu, Aug 20, 2015 at 3:09 AM, Michael B  wrote:

> Hi Tom,
>
> Thanks for your answer. That's indeed something that I need to think about
> more. However, as I understand it, the samples per symbol rate is equal to
> (samp_rate / data_rate). My sample rate is 500k, and my data rate (i think)
> is only around 100 or 200. See this figure of my (cleaned) signal:
>
> http://imgur.com/8pNqCop
>
> You see that it takes approximately 10 ms to transmit one symbol. This
> means 100 symbols per second. As I have 500k samples per second, this means
> 5k samples per symbol, right?
>
> However, I have tried setting the samples per symbol to 4, just to try,
> and the 'out of bounds' error still persists.
>
> Regards,
> Michael
>


Decimate decimate decimate. You should down sample your signal as soon as
possible to something reasonable. You want your sample rate to be large
enough to hold the information, but not too large that you're just wasting
cycles. Take your input signal down to reasonably represent the slow data
rate so that the actual sps is correct. You can just set these numbers
arbitrarily.

Tom




> --
> From: t...@trondeau.com
> Date: Wed, 19 Aug 2015 09:41:19 -0400
> Subject: Re: [Discuss-gnuradio] GnuRadio: Clock Recovery MM: imu out of
> bounds
> To: mibo...@hotmail.com
> CC: discuss-gnuradio@gnu.org
>
>
> On Wed, Aug 19, 2015 at 2:51 AM, Michael B  wrote:
>
> I have created a flowgraph, based on an example of Michael Ossmann
> <https://github.com/mossmann/im-me/blob/master/garage/garage-decode.py>,
> which takes in a signal, and should output bits.
>
> I need to use the clock recovery MM block, which I do not fully understand
> yet. However, after reading some blogposts, I am quite sure that I can
> leave most of the settings default, except for the Omega one. Here's my
> flowgraph:
>
> http://imgur.com/pHRXnZu
>
> When running this flowgraph, it gives me the following error:
>
> *thread[thread-per-block[5]:]:
> mmse_fir_interpolator_ff: imu out of bounds.*
>
>
>
> While searching, I stumbled upon this piece of code
> <http://gnuradio.org/redmine/projects/gnuradio/repository/revisions/ce3d887a47b47cb2d5351e14066ceb56b2b3c892/entry/gr-filter/lib/mmse_fir_interpolator_ff.cc>
>  in the source of GnuRadio:
>
>
>
>
>
> *int imu = (int)rint(mu * NSTEPS); if((imu < 0) || (imu > NSTEPS)) {
> throw std::runtime_error("mmse_fir_interpolator_ff: imu out of
> bounds.\n");   }*
>
>
> So, I suspect it is not due to my Omega setting (which might be wrong, I
> have to play with that setting), but that it is due to my Mu setting, which
> is just the default (0.5). However, I understand that Mu needs to be
> between 0 and 1, so I do not really understand what the problem is. Anyone
> who does?
>
> Environment details:
>
>- GNU Radio Companion 3.7.7.1
>- Running a GNU Radio live DVD in a virtual machine (VirtualBox
>4.2.12) on Windows 7.
>- Using Volk machine: ssse3_64
>
>
> Michael,
>
> I don't have an answer, but I can say where you're doing something wrong.
> You're samples/symbol (samp_per_sym) is definitely /not/ 2.5k. That's a
> massively oversampled signal and can't be right. You need to think what's
> the sampling rate of the system? What's the symbol rate of my signal? That
> will tell you the samples/symbol you need. It should small, like 2 or 4.
>
> Tom
>
>
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Re: [Discuss-gnuradio] GnuRadio: Clock Recovery MM: imu out of bounds

[Michael B]

Hi Tom,

Thanks for your answer. That's indeed something that I need to think about 
more. However, as I understand it, the samples per symbol rate is equal to 
(samp_rate / data_rate). My sample rate is 500k, and my data rate (i think) is 
only around 100 or 200. See this figure of my (cleaned) signal:

http://imgur.com/8pNqCop

You see that it takes approximately 10 ms to transmit one symbol. This means 
100 symbols per second. As I have 500k samples per second, this means 5k 
samples per symbol, right?

However, I have tried setting the samples per symbol to 4, just to try, and the 
'out of bounds' error still persists.

Regards,
Michael

 


From: t...@trondeau.com
Date: Wed, 19 Aug 2015 09:41:19 -0400
Subject: Re: [Discuss-gnuradio] GnuRadio: Clock Recovery MM: imu out of bounds
To: mibo...@hotmail.com
CC: discuss-gnuradio@gnu.org

On Wed, Aug 19, 2015 at 2:51 AM, Michael B  wrote:






I have created a flowgraph, based on an example of Michael Ossmann, which takes 
in a signal, and should output bits.I need to use the clock recovery MM block, 
which I do not fully understand yet. However, after reading some blogposts, I 
am quite sure that I can leave most of the settings default, except for the 
Omega one. Here's my flowgraph:
http://imgur.com/pHRXnZu

When running this flowgraph, it gives me the following error:

thread[thread-per-block[5]:]: 
mmse_fir_interpolator_ff: imu out of bounds.



While searching, I stumbled upon this piece of code in the source of GnuRadio:


int imu = (int)rint(mu * NSTEPS);   
  if((imu < 0) || (imu > NSTEPS)) { 
throw std::runtime_error("mmse_fir_interpolator_ff: imu out of bounds.\n"); 
  }


So, I suspect it is not due to my Omega setting (which might be wrong, I have 
to play with that setting), but that it is due to my Mu setting, which is just 
the default (0.5). However, I understand that Mu needs to be between 0 and 1, 
so I do not really understand what the problem is. Anyone who does?Environment 
details:GNU Radio Companion 3.7.7.1Running a GNU Radio live DVD in a virtual 
machine (VirtualBox 4.2.12) on Windows 7.Using Volk machine: ssse3_64
  

Michael,
I don't have an answer, but I can say where you're doing something wrong. 
You're samples/symbol (samp_per_sym) is definitely /not/ 2.5k. That's a 
massively oversampled signal and can't be right. You need to think what's the 
sampling rate of the system? What's the symbol rate of my signal? That will 
tell you the samples/symbol you need. It should small, like 2 or 4.
Tom
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Re: [Discuss-gnuradio] GnuRadio: Clock Recovery MM: imu out of bounds

[Tom Rondeau]

On Wed, Aug 19, 2015 at 2:51 AM, Michael B  wrote:

> I have created a flowgraph, based on an example of Michael Ossmann
> ,
> which takes in a signal, and should output bits.
>
> I need to use the clock recovery MM block, which I do not fully understand
> yet. However, after reading some blogposts, I am quite sure that I can
> leave most of the settings default, except for the Omega one. Here's my
> flowgraph:
>
> http://imgur.com/pHRXnZu
>
> When running this flowgraph, it gives me the following error:
>
> *thread[thread-per-block[5]:]:
> mmse_fir_interpolator_ff: imu out of bounds.*
>
>
>
> While searching, I stumbled upon this piece of code
> 
>  in the source of GnuRadio:
>
>
>
>
>
> *int imu = (int)rint(mu * NSTEPS); if((imu < 0) || (imu > NSTEPS)) {
> throw std::runtime_error("mmse_fir_interpolator_ff: imu out of
> bounds.\n");   }*
>
>
> So, I suspect it is not due to my Omega setting (which might be wrong, I
> have to play with that setting), but that it is due to my Mu setting, which
> is just the default (0.5). However, I understand that Mu needs to be
> between 0 and 1, so I do not really understand what the problem is. Anyone
> who does?
>
> Environment details:
>
>- GNU Radio Companion 3.7.7.1
>- Running a GNU Radio live DVD in a virtual machine (VirtualBox
>4.2.12) on Windows 7.
>- Using Volk machine: ssse3_64
>
>
Michael,

I don't have an answer, but I can say where you're doing something wrong.
You're samples/symbol (samp_per_sym) is definitely /not/ 2.5k. That's a
massively oversampled signal and can't be right. You need to think what's
the sampling rate of the system? What's the symbol rate of my signal? That
will tell you the samples/symbol you need. It should small, like 2 or 4.

Tom
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[Discuss-gnuradio] GnuRadio: Clock Recovery MM: imu out of bounds

[Michael B]

I have created a flowgraph, based on an example of Michael Ossmann, which takes 
in a signal, and should output bits.I need to use the clock recovery MM block, 
which I do not fully understand yet. However, after reading some blogposts, I 
am quite sure that I can leave most of the settings default, except for the 
Omega one. Here's my flowgraph:
http://imgur.com/pHRXnZu

When running this flowgraph, it gives me the following error:

thread[thread-per-block[5]:]: 
mmse_fir_interpolator_ff: imu out of bounds.



While searching, I stumbled upon this piece of code in the source of GnuRadio:


int imu = (int)rint(mu * NSTEPS);   
  if((imu < 0) || (imu > NSTEPS)) { 
throw std::runtime_error("mmse_fir_interpolator_ff: imu out of bounds.\n"); 
  }


So, I suspect it is not due to my Omega setting (which might be wrong, I have 
to play with that setting), but that it is due to my Mu setting, which is just 
the default (0.5). However, I understand that Mu needs to be between 0 and 1, 
so I do not really understand what the problem is. Anyone who does?Environment 
details:GNU Radio Companion 3.7.7.1Running a GNU Radio live DVD in a virtual 
machine (VirtualBox 4.2.12) on Windows 7.Using Volk machine: ssse3_64
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