Questions tagged [gnuradio]

GNU Radio is a free software development toolkit that provides the signal processing runtime and processing blocks to implement software radios.

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How to debug GNU Radio's C++ program from source code?

I recently started to look at some GNU Radio C++ code. Some complex code sections are not easy to understand, so I want to see how these code sections work. Since GNU Radio is written in Python and C++...
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GNU Radio filter normalization

I have noticed that all filter taps from the firdes class are normalized by dividing them over the sum of all taps magnitude, as shown in the example below for Gaussian Filter. Is this normalization ...
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GNU Radio buffer size [migrated]

How can I set custom buffer size for OOT python block in GNU Radio? My goal is block with input parameter input_buffer_len and block's geeral_work() function works with exactly input_buffer_len ...
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43 views

oQPSK/QPSK conversion with fractional interpolation

I once used a GNU Radio QPSK receiver for oQPSK demodulation. All I did was to "forcefully" delay the Q channel by half the symbol time. At the time, I was using a discrete number of samples ...
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GNURadio signal degradation *above* Nyquist rate

I am going through the basic tutorials for GNURadio, and I have a question related to the sample rate tutorial. In it they demonstrate the degradation effects of sampling at too low a sampling rate. I ...
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Comparing self-made O-QPSK signal with Zigbee burst (Q-QPSK acc. to IEEE 802.15.4)

What might be the cause of the worse baseband demodulation result of the bottom VSA screenshot compared to the demodulation result shown in the top screenshot ? Randomized Q-QPSK signal generated by ...
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68 views

Clock Recovery with FSK Demodulation in GNU radio

I'm working on demodulating an fsk signal sent from a cubesat on the ground to an antenna station. I'm trying to do it in GNU radio but I am not quite getting the original signal back. The cubesat ...
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Gnu radio C++ on Ubuntu 16.04

I've read posts that Ubuntu 16.04 is not a good fit for newer gnuradio. Since I can't update Ubuntu so I had to install 3.7.9. It works fine except the C++ part. Because GRC won't generate C++ code (...
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GNURADIO Busports and channel map for polyphase channelizer block

I am trying to implement the channelizer presented in this paper given in this link; http://www.trondeau.com/examples/2014/1/23/pfb-channelizers-and-synthesizers.html. However, I am experiencing a ...
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Gnu Radio symbol recovery

I have successfully built Simulation example: FSK. Everything works fine and I'm getting same results as in example. For the next step I would like to save demodulated binary data in file but I'm ...
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2FSK implementation with VCO GNURadio

I am fairly new to GNURadio. I am trying to generate a 2FSK with minimum frequency shift. Instead of multiplying with a 8MHz complex carrier, I directly use VCO to generate two frequencies. One at 7....
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GNU Radio head block doesn't finish simulation

My task is to generate finite number of samples and save it to the file. For that purpose I used head block but after setting the run option to: Run to Completion, the flowgraph doesn't stop, just ...
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58 views

GnuRadio additive scrambling/descrambling

How are you supposed to use GNU Radio additive scrambler block? The wiki documentation is very vague on the subject: Scramble an input stream using a Linear Feedback Shift Register (LFSR). This block ...
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pi/4 QPSK modulation/demodulation in GNU Radio

Is there any quick mechanism to create pi/4 QPSK or pi/2 BPSK modulation scheme in GNU Radio using Constellation Modulator object or Constellation Object? Or I need to write it by myself? Thanks in ...
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Clock recovery using Mueller and Muller adds noise affecting EVM or SNR (Two cases - GNU Radio & Python code)

The implementation of the Mueller and Muller clock recovery that I am seeing adds a large amount of 'noise' or degradation to the Error Vector Magnitude (EVM) to the symbols on the constellation. This ...
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SDR and amplitude modulated signals

Can I view every signal that has been transmitted using software defined radio as a amplitude modulated signal? For example I could make a frequency modulated baseband signal in GNU Radio and connect ...
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74 views

Fractional Resampler - GNU Radio

Fractional Resampler block in GNU Radio has parameter phase shift but there is a lack of information in which factors user has to provide this parameter (radians, degrees or samples?). There is only ...
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300 views

Source IO size “8” does not match sink IO size “4”

This is my first attempt at using GNU Radio. I am trying to do this example, which is a sine wave generator. The example works, so I am trying to connect the throttle block to the audio sink block. ...
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Frequency response of chirp signal changes when extracting burst from repeating chirp waveform

I hope i can make myself clear enough, even though i might not be familiar with the right terms. Using GNU Radio, i created a chirp signal with a sawtooth signal source into a frequency mod block, as ...
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GNU Radio Companion - Constellation Modulator - what is the reason behind the interesting Time Sink waveforms obtained?

For my setup of a Constellation Modulator block and QT GUI Time Sink block, with the symbol map for the Constellation Object being [0, 1, 2, 3], and the Constellation Points for the Constellation ...
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Doubt about sampling rate and spectrum with USRP and gnuradio [duplicate]

I have started working recently with software defined radio (SDR) as well as gnuradio. I have worked with digital signal processing for a while and one feature at one tutorial, which I saw for ...
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62 views

GNU Radio Companion - Constellation Modulator block - how to generate single constellation point only?

I'm beginning to learn about the Constellation Modulator block, and just trying it out by setting up a 4-QAM system, with the constellation points arbitrarily set as : [-1-1j, 1-1j, 1+1j, -1+1j] And ...
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GNU Radio Companion - generating a 4-QAM constellation - how to do it?

I'm doing the baby steps right now to learn about GNU Radio Companion. I'm using 3.7.13.5 at the moment. I'm just focusing on getting a simple binary stream together, such as '110100' (repeated) .... ...
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154 views

TypeError: primitive_connect() when executing in gnu radio

I'm building the frequency analyzer for RTL-SDR. But having problem in building and executing code. ...
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What is wrong with this GNURadio flow graph?

I am simply trying to modulate a wav file sampled at 22.05kHz, then demodulate it. The audio output is choppy and I get errors in the console output ("volk warning, no arch found... though I've ...
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Why does applying RRC to the signal increase bandwidth?

Please see this question: Why samples per symbols $\geq 2$ in the GNURadio Constellation Modulator block?. The first answer here says "filtering the signal, you have bandwidth expansion". ...
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Can I create my IF signal on SDR before bringing data to PC?

I'm relatively new to SDR's and I'm trying to determine what sort of BW I need for my laptop to get the best resolution possible for an FMCW system. I have an X310 Ettus with a UBX160 daughtercard ...
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190 views

gnuradio: Best way to sync to simple preamble

I never figured out a clean way to sync to a simple preamble in GNU Radio 3.7/3.8, so I built my own block to do so. It was a variation on the Correlate Access Code - Tag Stream block that simply cut ...
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21 views

Why I get another spectrum when upconvert an o-qpsk baseband signal with a bladerf compared to a hackrf device?

I have just start working with bladerf instead of former used hackrf hardware and I need to solve a problem. Currently I use the following bladerf hardware, libraries and firmware: bladerf (2.0 micro ...
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47 views

Why do I see a frequency shift from center when transmitting a QPSK via USRP with GNU Radio?

I am transmitting a QPSK signal via GRC and when I look at it on the spectrum analyzer, the signal is shifted away from my center frequency. This shift increases the higher the center frequency (i.e. ...
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What modulation is done when I connect a signal source to a USRP block in GNURadio?

When I connect a sinusoidal signal source to a USRP sink and upconvert the frequency, what modulation is done to convert the baseband signal to a passband signal?
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195 views

QPSK demodulator on GNURadio continuously loses phase lock

I am designing a QPSK demodulator to be used for receiving Meteor M2 (LEO satellite) signals (QPSK at 72Kbaud). However, I am finding a lot of problems in my way. First of all, this is the flowchart I ...
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Advice on generating stable FMCW waveform

I am trying to derive parameters for a triangular FMCW waveform such that the phase of the signal has consistency from one period to the next. Perhaps this is arbitrary and feel free to tell me so, ...
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55 views

Unstable frequency/phase when using external reference for Ettus B200

I am attempting to do a simple record of a CW, 250MHz signal at the Rx port of an Ettus B200 using an Anritsu MG369 signal generator. I am using the 10 MHz ref signal provided by the SG (output @ ~...
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Need to extract phase of incoming signal, how to find FFT bin of frequency of interest in GNU Radio?

When receiving a higher frequency signal, say 2 GHz, the freq as shown in frequency sink is often off by some amount (1-2 MHz) on the ettus B200. So I can't just assume the location of the signal is ...
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What is the successor to the GNURadio liveCD?

I used to burn and run the GNU Radio livecd - it was a very nice package that gave me a working gnuradio environment - with drivers and tools - without doing a lot of sysadmin or package management, ...
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29 views

Bit error rate transient

I see often people here posting about GNU Radio, I hope mine is not in the wrong place. I try to implement a demodulation chain and would like to measure its performance. I added a BER block and it ...
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75 views

Why samples per symbols $\geq 2$ in the GNURadio Constellation Modulator block?

Let's say I want to emulate the design of a modulator I am building "in real life". I'd like the components, input data rate, and output bandwidth to be the same as in the real system. If ...
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Why is the bandwidth for this QPSK system larger than expected?

Below is my gnuradio-companion graph. As you can see the sample rate is 100k, I am modulating with QPSK, and am filtering the waveform (RRC) with the "Excess BW" parameter, at 0.35. The ...
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160 views

Offset QPSK Demodulation using GnuRadio

I am currently trying to demodulate an Offset QPSK signal coming from a satellite using GNURadio. If I understood correctly, an OQPSK is a QPSK with one of the two bits per symbol delayed by half a ...
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64 views

Gnuradio fifo cntrl timed out looking for acks

I am using USRP N210 SBX for my experiment. It is a simple TX RX system with a tuning center frequency. I have uploaded the flowgraph. I am connecting to the USRP using a remote server CPU MHZ : 2300....
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64 views

LoRa sensing using USRP GNURADIO

I made a simple RF sensing using USRP N210. I am trying to detect LoRa transmission. A LoRa Node is operating at 915 MHz with Spreading Factor 8 and bandwidth 500 kHz. I have used a USRP UHD Source ...
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64 views

is it possible to introduce fractional delay in waveform in GNURadio?

I know this is a strange question as its hard to do in digital domain. I know it is a straight forward task if the signal is defined within N number of samples where I can go to Fourier transform ...
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108 views

How to use values from the output of a block in GNURadio

I want to use the output values of the top_block as a way of directing my flowdiagram. So I want the flowdiagram to take one path if the output of my processing ...
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76 views

QPSK transmission simulation

I am trying to simulate a QPSK transmission using GNU Radio following mpsk_stage6.grc example in Gnuradio tutorials. Currently I have no idea where is the problem and everytime I execute the flow ...
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Packet Encoder GNU QPSK Transmission

Hello everyone!. This is a template to QPSK transmission but Packet Encoder block is no longer available in new GNURadio versions, what do I need to replace this block in order to do a QPSK ...
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gnuradio - cpp block, cpu usage

I was working with message passing blocks (like es_trigger_edge, es_sink and more). When I connected (using msg_connect) other block in c++ that I wrote, I have noticed that simple processing of the ...
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gnuradio - flowgraph with cpp

I build a flowgraph in gnuradio, generated python code, change a little and run it using python. My question is, does building the flowgraph in cpp will provide better results (time)? (in other words ...
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Get data after “Correlate Access Code Tag”

in my Gnuradio flowgraph i have a stream of bytes that are 0x00 or 0x01. Using the "Correlate Access Code Tag" block, I am able to insert a tag just after that a specific Access Code has ...
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400 views

Is Bluetooth Low Energy jamming possible with an SDR like the HackRF on GNURadio?

It seems like BLE jamming is technically possible by just jamming the 3 advertising channels 37, 38 and 39 https://github.com/lws803/BLE-jammer and it has been proven to work on an STM32 + 3x NRF24l01 ...