Douglas Geiger | 23 Oct 03:35 2014

[coproc] WG call next week

I am scheduling the next Co-Processors WG call to take place next Wednesday, October 29, 2014 <at> 2:00pm US/Eastern time (6:00pm UTC). I'll send out a reminder next week. Currently there is no agenda, so if you plan on attending and have anything you wish to discuss, please add it to the wiki page (


Doug Geiger
doug.geiger <at>
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Richard Bell | 22 Oct 23:40 2014



I just installed PyBOMBS on Ubuntu 14.04. I'm noticing that sometimes the icon labels are readable, but a lot of them are off the screen and can't be selected, like UHD. The last icon available to install for me when this happens is osmo-tetra.

To overcome this, I close PyBOMBS and restart it. Usually after this, I am able to see all the icons, but they are squished in such a way that I can't read the labels of that are missing a thumbnail picture. I can read UHD, gnuradio, gnss-sdr, etc. because those have non-default thumbnails. All the icons with ? thumbnail pics are unreadable.

Is this a known bug and is there a workaround?

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Lev Serebryakov | 22 Oct 23:39 2014

rational_resampler vs pfb_arb_resampler filter design -- why such strange cut frequencies in both cases?

 I'm looking at filter design procedures for rational_resampler and
pfb_arb_ resampler and see contradiction between them.

 Lets assume downsample with rate 3/4 or 0.75. Lets source sample rate
to be 10000 (so, target sample rate should be 7500), but, in fact, it
is irrelevant.

 rational_resampler could be configured for this task with
interpolation=3 and decimation=4. We'll set fractional_bw to "0.4" to
match arb_resampler "80%" multiplier. design_filter() method in will create low-pass filter with:

 gain = 3
 FS = 1
 transition center = 0.4/3 = 0,1(3) of 30000 = 4000 (!!!)
 transition width = 0.1

 It doesn't look resonable, as 4000 is more than 3750 which is Nyquist
frequency for targer sampling rate.

 Lets look at arbitrary resampler (

rate is < 1. so it takes first branch:

  gain = 32 (default number of filters)
  FS = 32 (WHY?!)
  transition center = 0.5 * 0.75 * 0.8 = 0.3 (And it should be in Hz!)
  transition width =  0.15

 As you can see, parameters are rather different. But in this case
filter should be roughly the same, because task is the same! We need
to filter out all frequencies below 3750!

 And both methods raise the questions. I could not say, that one of
the methods looks good to me. Questions are:

 (1) Why rational resampler doesn't take decimation in account when
calculates bandwidth? It design filter which will correctly reject all
images in upsample, but looks like aliasing is possibly when effective
ratio is less than 1, as only interpolation is used in bandwidth
calculation and resulting filter "effectively" works at upsampled rate.

 (2) Why arbitrary resampler set Fs to number of filters and AFTER
that pass bandwidth numbers as normalized to 1, not to this Fs?! 0.3
is perfectly good (may be slighly conservative, but Ok) transition
band center, but in this case this 0.3 will be taken for FS=1, and
here FS=32 (number of filters) is used, so it will be 32 times too low

 Are these two peculiarities two bugs, really, or I don't understand

 Yes, I've read harris' book on multirating processing, and AFTER this
book I got these questions.


Black Lion AKA Lev Serebryakov
Richard Bell | 22 Oct 21:01 2014

Installing GNU Radio

Hello Everyone,

I hate asking questions like this, but I need help installing GNU Radio. The objective is to have GNU Radio and UHD installed on Ubuntu 14.04 so I can use it with my USRP N210. The problem I have is this:

1) I don't like using the ettus easy install for 'UHD+GNU Radio' because their GNU Radio is usually several versions behind the most up to date version. I want control of what version I use.

2) I can't use apt-get install gnuradio because I need to install UHD first and apt-get install also installs a very old version of gnuradio.

What's left for me? Do I have to compile source code and go that route? I'm far from being a professional programmer, so I do not trust myself getting that done correctly. I remember reading something about a PyBombs install process related to this I think. Is that an option?

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Raydel Abreu (CM2ESP | 22 Oct 17:30 2014

PSK demodulation of a sub-carrier sent over FM


I had experimented with simple PSK reception with GNU-Radio when the carrier is directly phase modulated.

However I would like to know how can I demodulate a PSK transmission which is carried over a typical FM signal.

Kind regards,

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Gisle Vanem | 22 Oct 15:16 2014

log2() missing in MSVC v16

Hi again.

I finally was able to build most of GR using CMake and
the generated "Visual Studio 2010" gnuradio.sln file. Since I'm
not sure if this platform is supported or not, it may be a futile attempt.

I patched cmake/msvc/config.h since I figured that was the active one. 
IMHO it's confusing that 'volk\cmake\msvc\config.h' seems to include 
almost the same stuff.

Well, volk now uses the log2() function which my MSVC v16
doesn't have. And etc. uses these 
ISO-646 "keywords" like 'not', 'and' etc. I solved these errors by 
patching cmake/msvc/config.h like so:

 <at>  <at>  -29,6 +29,16  <at>  <at> 
 static inline double rint(double x){return (x > 0.0)? floor(x + 0.5) : ceil(x - 0.5);}
 static inline float rintf(float x){return (x > 0.0f)? floorf(x + 0.5f) : ceilf(x - 0.5f);}

+static inline double log2 (double x)
+  return log ((double)x) / log (2.0F);
+// Use of ISO-646 keyword ('not', 'and' etc. needs this header.
+#ifdef __cplusplus
+#include <ciso646>

(the cast in log2() was need to resolve any C++ ambiguty).
Not sure if this hurts if VC 2012+ already have log2() in it's <math.h>.


Here is how I used VC 2010 Express to build:
  cmake -G "Visual Studio 10 2010"
  msbuild -nologo -p:Configuration=Release -fileLogger 
    -fileLoggerParameter:Summary;Verbosity=minimal;LogFile=gnuradio-build.log gnuradio.sln

Anybody else having success with VC 2010? Or are you Windows users
(Ettus?) using VS 2012 only? Seems like Win-XP is unsupported since I get
a call to the non-existant GetThreadId(). It's in kernel32.dll, but on Vista+ only.

Su Li | 22 Oct 14:51 2014

How to save bit stream?


After demodulation, I get a stream of "0" and "1" in UChar format, I want to save this stream to a file and have a look at these raw bits before decoding them. I tried to use "File Sink" block to save them, but I cannot open the saved file with "gedit". It can be opened with  "GVim", but the content are not 0 and 1. They are "^ <at> " and "^A".

Is there anyway to save the bit stream so that when I can open the saved file I can get the stream shown as "0" and "1"? 

The flow graph is shown as following

​Thanks in advance.

Best regards,
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Marcel Stolz | 22 Oct 10:57 2014

AtributeError with OOT Module


I am trying to install an OOT module into my GNURadio distribution. I 
can integrate the module into GRC and use it in the flowgraph. However, 
when I try to execute, I get the following Error:

Traceback (most recent call last):
   File "./", line 76, in <module>
     tb = top_block()
   File "./", line 43, in __init__
     self.LTE_Analysis_pbch_bch_0 = LTE_Analysis.pbch_bch(samp_rate)
AttributeError: 'module' object has no attribute 'pbch_bch'

I assume that there is some problem with the SWIG-glue between python 
and my C++ code. However, several hours of googling have not brought up 
any solution to this issue. As has been posted previously on this list, 
this issue "has come up recently" on some installations. I have tried to 
install the module and execute it on the GNURadio Live DVD that was 
distributed via the mailing list yesterday - yet, the error remains.
Any help on this would be very appreciated!
I have attached some files which I think could be helpful for tracking 
the error.

Best regards, Marcel

Universität Bern
Institut für Informatik und angewandte Mathematik
Communication and Distributed Systems Research Group

Marcel Stolz, BSc
Master Student

Neubrückstrasse 10
CH-3012 Bern
mailto:marcel.stolz <at>

/* -*- c++ -*- */


%include "gnuradio.i"			// the common stuff

//load generated python docstrings
%include "LTE_Analysis_swig_doc.i"

	#include "LTE_Analysis/pbch_bch.h"

%include "LTE_Analysis/pbch_bch.h"

GR_SWIG_BLOCK_MAGIC2(LTE_Analysis, pbch_bch);
Attachment (pbch_bch.h): text/x-chdr, 1838 bytes
Attachment ( text/x-python, 2584 bytes
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Sebastian Komorowski | 22 Oct 08:52 2014

WiMAX scanner


I am interested in WiMAX technology (802.16e). In my research I am
dealing with algorithms for admission control in Matlab. Typically these
algorithms are located “within base station” – although they are not
standardized by any organization. In simulations it is simple to “deploy
them” as they are located inside BTS source code.

As regards verification and validation of such algorithms I am currently
using well known simulator which is ns2 – i.e. well known to the
community. It is clear however that “simulations vs reality” is not
always very close…. That is why I am interested in collecting data from
real network in a vendor agnostic way (in general from any network i.e.
build upon BTSes delivered by any vendor) – it means that I would like
“observe” traffic intensity/duration/etc directly from the radio. I am
using PureWave 6600 at university premises.

The input data for the algorithms I am interested in is the wireless
connection characteristics e.g.: connection requests, time of connection,
type of traffic, connection close, etc.

Unfortunately to my knowledge there is no one-fits-all (or virtually any)
solution to communicate with inside components of a BTS in an automated
manner (i.e. from within a software program that is learning for best
policy etc).

That is why I have started to think about using USRP (or its brother from
NI / or any other SDR) to play a role of passive probe for WiMAX wireless
signalling. I have seen that there is a “wimax scanner” project but it
seems unfinished (or would it actually be operational in the area I
mention?). Please let me know:

1.       Is it possible to use “wimax scanner” with USRP right away
(i.e. without much effort spent on programming)?

2.       Is wimax scanner full featured solution? (i.e. what can I do with

3.       What statistics I could capture with it?

4.       What limitations does it has?

5.       Are there any plans for continuing its development?

6.       Do you know if there is already happening an approach to develop
complete WiMAX stack as there is for GSM – OpenBTS…?

Thank you for the assessment of my question or any hints.



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Alex Zhang | 22 Oct 02:08 2014

iir_filter does not work with specified feedback taps?

Hi All,

Any guys who ever used IIR filters? I got problems as below:

I want the IIR filter works as:
y[n] = 1.8*x[n] + 0.8*y[n-1]
Then I set the feed forward taps as [1.8], feeback taps as [0.8], just like 
self.iir_filter_xxx_0 = filter.iir_filter_ffd(([1.8]), ([0.8]), True)

But my testing result show that the feedback taps are not involved in computing at all, thus my output turns to 
y[n] = 1.8*x[n] 

I don't know anything wrong happened to my usage...
Need help. Thanks



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Garver, Paul W | 21 Oct 22:00 2014

gr-qtgui Waterfall Time Axis

I have some large spectrum records and I would like to use GR for analysis in a a sort of "off-line" mode.  I want
to visualize the data using the spectrogram and then identify subsets of interesting features (e.g. WiFi
Packets in 2.4 GHz) by frequency and time coordinates.  Essentially, I want to know what index in the file
certain features correspond with so I can save them as separate files.  To this end, I've found
gr_spectrogram_plot very handy, but it doesn't quite do what I want because the y-axis which displays
time isn't showing up correctly.  My y-axis is always 0.0, and the cursor highlight also reads 0.0
(although the frequency is correct).  However, the qt spectrogram appears to have correct time
information when I make a simple file source -> qt spectrogram sink.  

I'd like to fix this issue so I've been pouring over the code in gr-qtgui.  I don't have much experience with
QWT or Python GUIs in general.  From what I can tell, there are methods for frequency axis and intensity
scaling, but not time.  Is this true or am I missing something in the API?  The historyExtent parameter in the
WaterfallData constructor appears to get hardcoded to 200 in
(gr-qtgui/lib).  It would also be nice to toggle between the time and sample number.

I'm happy to do the work to implement this.  Could someone point me in the right direction here?  Thanks!