John Meloche | 19 Dec 14:56 2014

GRC Install - Pybombs vs Binaries

Hello experts,
I have been using linux and GRC for about a year and as such I am still pretty 'green' about a lot of stuff, but I am learning and hopefuly someone will be able to advise me about me questions.
I use GRC at work behind a firewall.  Installing via Pybombs is very cumbersome if not impossible only due to the fact that Pybombs 'fetches' various dependencies, etc from various locations on the internet.  The firewall is preventing access (as it is designed to) to some parts of github, etc.  So the only way to use pybombs in my circumstance is to bring the computer off site for the installation to complete without errors.  I have recently learned how pybombs can be used to install or revert to a specific version of GRC.  The binary package which is installed with the 'apt-get install .... " terminal command is allowable from behind the firewall and seems to be a good solution for me going forward.  At a training course from Corgan Labs in the spring we were warned that binaries will be phased out in favour of pybombs.
This leads me to a few questions:
1) Will the binaries be available and supported into the future or will pybombs eventualy be the method of choice?
2) Is there an advantage to using one method over the other?
3) Is there a way to identify a package version that is considered to be long term support compared to a minor bug fix (similar to the way that Ubuntu has identified its versions)?
Best Regards,
John Meloche
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Richard Bell | 18 Dec 19:39 2014

uhd_fft not resonding

I'm using Ubuntu 14.04, UHD_003.008.00-18-g864f84b5 and GNU Radio 3.7.6

Whenever I start uhd_fft from a command line, the window opens and starts to plot. After about a second, the window goes into not responding mode, where it greys out and you can't click anything. Does anyone know what could be causing this behaviour? Is it a local setting of mine?

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Martin Braun | 18 Dec 19:02 2014

Dev Call December

Starting now, YT URL:

Ping me in #gnuradio if you want to join.

Mostafa Alizadeh | 17 Dec 21:11 2014

connecting GNURadio to xilinx evaluation board


I have KC705 evaluation board of xilinx: 

I have also a daughter board of fmcomms1: 

I want to use GNURadio alongside of this board. I suddenly saw Zynq system here (I don't know anything about Zynq system):

Is it possible to use KC705 with GNURadio? 
To be specific, is there any FPGA program for KC705 to integrate it with GNURadio? 

Any suggestions? 

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David Halls | 17 Dec 18:41 2014

Vectors for GNU Radio Python Blocks

Hi all,

How do I write the init section for a Python block with an complex input vector of length v_len, so I need to adapt the following...

"def __init__(self, Nb, Ns, mapping, v_len):



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gaddam yamuna | 17 Dec 18:39 2014

Trouble at OFDM modulation FFT waveform

 Good Morning Sir,
               I am an M.Tech student, want to implement ' OFDM Modulation & De 

Modulation on GNU Radio'.

         Sir i unable to get the OFDM modulation FFT waveform .Will you please 

help in parameters of WX GUI FFT block or any settings which give clear 

Frequency plot ( FFT PLOT)  of OFDM Modulation like in below figure.

                           Thank you Sir.

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M Dammer | 16 Dec 18:03 2014

pipe data from GRC through shell command (like gr-pipe in 3.6) ?

I want to pipe data from GRC "through" a command running in the linux 
shell. I found gr-pipe on github, but it seems to be for 3.6 only. Until 
now I have used file sinks / sources and FIFOs, but this is inconvenient 
as FIFOs have to be created and things have to happen at a specific 
place in the filesystem. I'd rather find a way to directly connect to 
STDIO of a given command.
thanks Mark
Rui Zou | 16 Dec 17:21 2014

How to pass time tag into usrp sink as a parameter ?[hurry...]

I would like to implement the process as follows at the Rx side: Record 
the time when the first sample arrived, and then wait for a certain 
interval and then send ack back to Tx. Meanwhile, finish the cfo 
calculating and compensating.
Here is my whole flow graph design. (Each means a block)

                            pkt_dtc-> cfo_calc -> file_sink
                                             cfo_calc -> cfo_cpst
                                        file_source -> cfo_cpst -> usrp_sink

where pkt_dtc, grab_time_tag and cfo_calc was done myself with C++. 
However, My question are:
1. Is it correct of my whole desgin (I want to implement them in one top 
block) or are there any easier solutions ?
2. After the block grab_time_tag, how should I pass the time information 
(directly got from the method get_tags_in_range) into the usrp_sink as a 
parameter so as to send ack at the intended time? Should I write in 
Python(but they are not the same level) or C++(but I can't rewrite a 
usrp_sink) ?

Any doubts or suggestions are highly appreciated !
Thesis 2015 | 16 Dec 06:24 2014

HELP: USRP1+WBXv3 "Overflow"

Good day,

We are beginners using the USRP1 with WBX v.3 50-2200 daughterboard and GNU radio Companion version with UHD_003.008.000-18-g864f84b5 installed on Ubuntu 14.04 LTS operating system. Our goal in using these is to create an SDR WBFM receiver.

We have followed what was done in the video posted by the ettus research ( but have encountered some problems. As we ran the GRC file, both the FFT plot and Scope plot appeared but all we could hear are static sounds together with the script shown below:

Executing: "/media/thesis/Data/Downloads/Thesis/FM Reciever using GRC/"

linux; GNU C++ version 4.8.2; Boost_105400; UHD_003.008.000-18-g864f84b5

Using Volk machine: sse4_1_64_orc
-- Opening a USRP1 device...
-- Using FPGA clock rate of 64.000000MHz...

UHD Warning:
    The hardware does not support the requested RX sample rate:
    Target sample rate: 5.000000 MSps
    Actual sample rate: 5.333333 MSps
-- Tune Request: 88.100000 MHz
--   The RF LO does not support the requested frequency:
--     Requested LO Frequency: 88.100000 MHz
--     RF LO Result: 88.099634 MHz
--   Attempted to use the DSP to reach the requested frequency:
--     Desired DSP Frequency: -0.000366 MHz
--     DSP Result: -0.000366 MHz
--   Successfully tuned to 88.100000 MHz
INFO: Audio sink arch: alsa
>>> Done

As we are doing all the simulations, we did not use any antenna yet. However, we are waiting for the arrival of the antenna LP0410 400 MHz to 1 GHz Log Periodic PCB directional antenna, at 5-6dBi Gain. We have purchased this antenna for it is capable to receive signals from 88.1MHz to 107.9MHz (frequency range of all the FM stations that we are about to receive).

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Richard Bell | 15 Dec 19:28 2014

Odd Behavior

Problem: Real and Imaginary outputs of CPFSK sometimes seem flipped in the transmitter.

I'm using the CPFSK block to modulate for a binary FSK radio. All that I reference here is in the transmitter. There are 3 input paramaters for the block: k (modulation index), A (Amplitude) and N (Samples/Symbol). The relationship between input and output of the CPFSK block is shown below and found in the source code:

out[n] = A*exp( j * k * pi * 1/N * n * input[n] )

where input[n] = +1 or -1 is the input data to the block.

Now with that all setup, here is the odd behavior. Since input[n] is only +1 and -1, I expect the real part of the output to remain unchanged and the input changes, because cos(-x) = cos(x) and I expect the imaginary part to flip signs as the input changes because sin(-x) = -sin(x). What I see is sometimes the cos will be flipping signs with the sin remaining constant. It is as though the inphase and quadrature arms were reversed.

I am looking at the real and imaginary output of the CPFSK block in the transmitter. Because we are in the transmitter, there are no channel effects or synchronization effects that come into play to cause this.

Does anyone know what could cause this?

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Tom Rondeau | 15 Dec 16:59 2014

Hackfest at TU Delft

Hey everyone,

As a reminder to the community, we're having a hackfest at TU Delft during the last week or January. We still have some room left if there are a few more people out there who think they can make it. Turns out a few of the guys I was expecting are "working on a phd" and think that they are "busy." Ping me if you haven't already about joining us.

I've also started a basic page about the hackfest that will get filled in as we go:


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