Signal Processing

Questions tagged [gnuradio]

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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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Frame synchronization for single carrier burst applications in fading channels

I recently started to implement communication systems with software-defined radios in GNU Radio. In my system design, I am planning to transmit data in burst mode, the frames will be not sequentially ...
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23 views

How to recover modulation symbols？

I am using GNURadio to send and receive a limited number of modulation symbols. I have constructed the following flow chart:random source(no repeat)->chuncks to symbols(file sink1)->polyphase ...
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29 views

How to depict small-scale fading effect using SDR boards?

In summary, I want to depict small-scale fading. I am using two HackRF One boards; one as transmitter and another as receiver. If I produce a signal (e.g. QPSK), what property of received signal ...
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44 views

GNURadio Guided Tutorial PSK Demodulation Example

I have been reading and doing the steps on this webpage of GNUradio : https://wiki.gnuradio.org/index.php/Guided_Tutorial_PSK_Demodulation In the middle of the page, there is a section: "Using ...
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39 views

Spectrum Smoothing

I recently stumbled upon this GNU Radio flow graph which smooths spectrum. Block parameters are seen in image attached below. Also visually results doesn't change if I take out "Keep 1 in N" ...
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36 views

Reed-Solomon error correction in GNU Radio

Can someone please explain how to define parameters for Reed-Solomon decoder correctly in GNU Radio? I have already looked at ETSI EN 300 744 Clause 4.3.2 , but it does not explain how to choose ...
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55 views

How to decode a binary Signal in a wav file into binary - sent here from stackoverflow

I'm doing a puzzle that gets me to call a phone number which produces a load of beeping sounds. Putting this into audacity as a spectrogram produces this: Zoomed in it looks like this: This looks ...
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18 views

Why the output data quantity of the channel model in gnuradio is less than its input data quantity?

I am facing a problem and I have created the following flow diagram to illustrate the problem. As shown in the figure, my input is 0,1+1i,2+2i,...,199+199i, I set the parameters of "channel ...
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32 views

Digital Selective Calling (DSC) Decoder in GNU Radio

I’m attempting to develop a GNU Radio FSK decoder for Digital Selective Calling on marine VHF but I seem to be stuck. I got my hands on a Standard Horizon handheld marine VHF unit with DSC capability ...
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53 views

How can I fix bad clock recovery for bursts with short distance?

I use GNURadio as a prototyping tool to build a receiver for a digital signal of a home appliance. The signal itself looks good so far. Also the symbol synchronization works well using the symbol ...
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38 views

Decimation with dynamic factor in GNU Radio

In a GRC flowgraph I have a custom OOT block which periodically sends a PMT message to the "command message port" of the "UHD: USRP Source Block" (for set the RF center frequency ...
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47 views

Implementing OQPSK in Gnu Radio Companion

I am currently trying to realize this block diagram in Gnu Radio Companion: Before using a file source block with the binary I want to send, I plan on just using a vector with an alternating 1,0 ...
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82 views

Relationship between sampling rate and bandwidth in gnu radio

I wondering something. While working with adalm pluto sdr in gnu radio, the sample rate I enter in the source block is actually bandwidth. I know that bandwidth must be half of the sampling rate ...
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To GNU Radio users - how you find a block class writing own python code using GNU Radio library?

How are you guys finding an interesting block class among available GNU Radio modules? I find it difficult to write own flowgraphs writing in python. Assume I want to use Constant Source block, I ...
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17 views

Chunks to symbols block, what is the use of 'dimension' parameter?

Can somebody explain me what is the use of 'dimension' parameter in Chunks to Symbols block in GNU Radio? As far as I understand it relates to dimensions in symbol table given as a first argument, am ...
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24 views

wireless card in place of an antenna/ hack a robot

My nephew has this toy robot and asked me to build a new remote for it. It's a "Cady Wida" robot from JJRC. When I opened it up, a tag inside said "40 MHz" and the board sported a &...
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59 views

AWGN noise variance in upsampled BPSK signal

When I simulate BER for basic PSK schemes, I set the IQ complex noise variance to $\sigma^{2} = \frac{E_{s}}{2*R_{m}*R_{c}}*\left( \frac{Eb}{No}\right)^{-1}$ where $E_{s}$ = Energy per modulated ...
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38 views

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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50 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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2answers
45 views

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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23 views

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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119 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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28 views

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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60 views

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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56 views

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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85 views

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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56 views

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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83 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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1answer
70 views

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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1answer
126 views

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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1answer
47 views

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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126 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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582 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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64 views

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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39 views

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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76 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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307 views

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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219 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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1answer
50 views

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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1answer
36 views

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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55 views

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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296 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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24 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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1answer
65 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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16 views

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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255 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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45 views

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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1answer
59 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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49 views

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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