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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GNU Radio GMSK modulator

I'm looking at the GNU Radio GMSK modulator block. The Gaussian taps are somehow convolved with a rectangular window with 4 * samples-per-symbol taps owing to the fact for GMSK, the filter spans four ...
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Not sure why I get errors of missing blocks when trying examples in Gnuradio Companion

I just started working with GNURadio without much of familiarity about this software. I found a couple examples online and I tried to run them but I get many Missing Block errors. Thats how it looks ...
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Synchronization and downsampling after matched filtering - GNURadio polyphase clock sync

I am trying to model a QPSK transmission. For this, I am using the software GnuRadio and more specifically the block polyphase clock sync. This block performs timing synchronization for PAM signals by ...
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i want to replicate a network analyzer using GNU radio and USRP B210

i want to create a flowgraph for network analyzer using GNU radio and USRPB210 and to test a device ?kindly tell me where to start and attach a workspace diagram if you have ? want to replicate a ...
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Impact of the sample rate of the emitting signal : communication between HackRF One and USRP NI 2921

I am transmitting a 1 kHz cosine wave with a HackRF One. I receive it with a NI2921 USRP at a sample rate of 200kHz. All the process is on GNURadio Companion. I changed the sample rate at emission ...
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SDR : Signal divided between the edges of the receiving window

I'm using a SDR (specifically the RTL-SDR) to analyse the spectrum and i noticed a phenomena that does not seem logical. The signal I want to capture is centred on 868.3 MHz and the central ...
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62 views

Communication between two USRP : mismatched spectra between transmission and reception

I am trying to make two USRP communicate between each other : for the transmission, I'm using an HackRF One USRP and for the reception a NI 2921 USRP. As a first test, I'm trying to send different ...
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71 views

How can an SDR recover a high-frequency signal?

How can software-defined radios operate at high frequency? The Nyquist rate dictates that you need to sample at twice the frequency to fully recover the signal. If my signal of interest is modulated ...
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QPSK Phase Recovery : Maximum-likelihood Vs Costa's Loop

I have implemented a QPSK Costa's loop in GNU Radio and run some BER benchmarking. All is going well. Out of curiosity, I'm trying to implement the Maximum Likelihood phase recovery shown below. For ...
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71 views

Offset QPSK detection in GNU Radio - Sample delay

An OQPSK detector is being tested in GNU Radio. The architecture was obtained from Michael Rice's Digital Communications - A discrete-time approach. The flowgraph is shown below. The modulator ...
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80 views

FFT-based coarse carrier recovery for QPSK

An FFT-based coarse frequency acquisition block is being tested in GNU Radio. The algorithm used can be found on the GOES satellite user manual and is summarized in the figure below. The algorithm ...
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GnuRadio FM Receiver: Heterodyne vs Xlating vs Direct

I'm trying to build an FM receiver (and eventually transmitter) in GnuRadio that will be able to interact with my local repeater. Starting with WBFM (because I can consistently pull in broadcast ...
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Find the SNR of an FM broadcast signal in GNU Radio?

Any ideas on how to find the SNR of an FM broadcast signal in GNU Radio? I have seen an SNR estimator block for MPSK modulation? Do I need to create an OOT block for calculating SNR of FM signals or ...
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QPSK signal 'passthrough' - not working as expected

as a fun project I am trying to build Quadrature Phase Shift Keying (QPSK) modulator & demodulator for a Digital Video Broadcasting (DVB) application. I am using the LimeSDR mini as my hardware ...
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GNU Radio | Transceiver loopback adapted | Transmission stops unexpectedly

(This is a follow up question to a previous question: link) I have implemented a flowgraph of a transceiver loopback inspired by the examples found at ...
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GNU Radio | Async FEC encoder/decoder loopback | Issue during decoding?

I have implemented a loopback flowgraph intending to perform the following: FEC encode (repetition code) an input stream in16_2.dat Store the encoded stream as <...
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Any ideas on creating a GNU radio block for scanning active frequencies (FM/AM/DAB/DVB-T)?

I am trying to create a GNU Radio block that scans the active frequencies, let's say for FM/DAB channel. I have seen scanner implementations in c++/python but are not compatible with GNU Radio. Can ...
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GNU Radio | Packet Encoder/Decoder | Unwanted bytes added to the transmitted stream

(A follow up question can be found here: link) In an attempt to understand how the packet encoding blocks work I tried to mimic the experiment performed by Aaron, published in this post, but reduced ...
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Changes in amplitude after Quadrature Demodulation

I'm getting the FSK signal from the satellite in I/Q format (see the last 2 waves at the bottom of the picture). After applying Quadrature Demodulation, I'm getting the top wave. The questions are:...
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77 views

GnuRadio's SNR estimators usage

I'm trying to calculate the SNR of a satellite signal using GRC, but all of the 4 offered estimators either have a lot of -NaN values or are ~35dB throughout the entire recording. (I just connected ...
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40 views

Channeling two named PIPEs with a GNU Radio flowgraph | String transmitted on one end does not reach the other end

1) I created two named PIPEs: $ mkfifo pipe_in $ mkfifo pipe_out 2) Then connected pipe_in to ...
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69 views

Working principal of MIMO(2 by 2)-OFDM (802.11n)

I have gained basic knowledge on MIMO-OFDM from online sources and in process of building 802.11n standard in GnuRadio+USRP B210. My goal is to analyze the channel state information and play with it ...
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44 views

Creating GNU radio flowgraph for continuous switching between transfer and receive mode

I am having a hackrf-one device which can either transmit or receive signals. I am having a GNU radio flowchart which has a selector block which allows manual switching. I am not able to switch it at ...
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Can a software defined radio with a frequency range of 300 MHz – 3.8 GHz detect AM (535 to 1705 KHz) and FM signals (88 to 108 MHz)?

I am interested in knowing whether BladeRF SDR with a frequency range of (300 MHz - 3.8 GHz) detect AM and FM frequencies? Also, how important is the sampling rate of the SDR. For example, BladeRF has ...
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217 views

Residual carrier tracking with PLL

Residual carrier systems such as PCM/PM/NRZ and PCM/PM/Bi-phase are common in space applications. Compared to suppressed-carrier systems such as BPSK, the literature sources on residual-carrier ...
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212 views

EbNo, SNR, and BER simulation for BPSK with convolutional code

Im currently simulating BER performance of CCSDS convolutional code. Im having some troubles in specifying EbNo and SNR in gnuradio blocks. From matlab webpages on BER simulation for RRC pulse and ...
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How can I tune into two FM frequencies at the same time?

I have a file source for a FM radio capture and have a working FM tuner. I need to tune into two frequencies and listen at the same time. Any help to accomplish this would be appreciated! Current ...
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90 views

Phase noise modeling using gnuradio IIR filter

I need some advice regarding phase noise modeling using gnuradio IIR filter. I'm trying to synthesize phase noise (multiplicative) with a given noise mask. In one paper, the authors were able to ...
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33 views

Group delay emulation in GNU Radio

I'm trying to test an equalizer against group delay distortion of a satellite communication link. According to the CCSDS standards, It is agreed to simulate high-order modulation system with in-band ...
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187 views

GNU Radio loop bandwidth normalization

From GNU Radio documentation, the control_loop block proposes loop bandwidth values in the range $[\frac{2\pi}{200}, \frac{2\pi}{100}]$ in radians per sample. Some blocks, like the new timing symbol ...
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“Image Processing” [closed]

I'm an Italian student. I'm studying Gnu Radio and I would like to upload a photo, can I upload it with "file image source" or other blocks? I need to make FFT of an a image. -> image 2D Thank you ...
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128 views

Recovering data from mystery signal

I was scanning the airwaves using my RTL-SDR and found a signal being broadcast locally that I was able to receive. When I configure the SDR Console V3 software to NFM, I get the following audio. (Wav ...
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379 views

Why am I seeing a negative frequency on FFT graph in Gnu Radio Companion? [closed]

I have a pretty simple flow here in GRC, but for some reason I'm seeing a negative frequency mirroring the 10khz signal that I'm generating. What's causing this negative frequency to show up in the ...
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174 views

am I recording LTE uplink signals?

I have this app in my phone which tells me the LTE UL frequency and power: so I went with my SDR and measured the received signal at that frequency: Now, how can I be sure this is the transmitted ...
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126 views

Dynamic loop bandwidth for a Costas loop

I'm using a Costas loop for carrier recovery. The BER vs SNR (from GNU Radio Simulation) curve for different loop bandwidths (0.03,0.05 and 0.07) is shown in the graph below. It can be seen that the ...
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120 views

Emulating a Variable Delay

I am trying to emulate a satellite link where the delay time between the satellite and ground station changes over time due to the satellite's motion. I plan do this by converting to the frequency ...
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76 views

Band-edge filtering for an RRC pulse-shaped manchester/biphase-encoded bitstream

Band-edge (derivative matched) filters can be used to generate an error signal for frequency locked loops (real part) or symbol timing loops (imaginary part). The derivation of the band-edge filters ...
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155 views

Blind equalization with constant modulus algorithm in GNU Radio

I'm currently simulating the effect of multitap channel on BPSK as well as its remedy i.e. equalization. The modem is expected to work with satellite TT&C transponder. The communication channel ...
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Pulse shaping with RRC : Number of taps

I am running a BPSK flowgraph in GNU Radio which is based on RRC pulse shape. I noticed that the BER is quite poor when the number of taps is low. However, using the number of taps around $20\times ...
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54 views

Analog equivalent for transition width in Digital radios

I have started off with GNUradio and I am not sure if I understand the transition width parameter available in GNU radio companion filter blocks . As per online documentation transition width of a ...
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1answer
369 views

Timing recovery in GNU Radio : Variable rate vs Fixed rate operation

I have been wondering about the implementation of timing recovery blocks in gnuradio. In literature, for asynchronous sampling, all that is needed are error detector (MM, ML, Gardner etc), a loop ...
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237 views

GMSK/GFSK BER simulation in GNU Radio : How to specify signal energy

In GNU Radio, BER vs SNR can be measured by fixing the signal energy and varying the amplitude of the noise source block. For example, in BPSK, we have transmitted signal $s\left(t\right)$ with a ...
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399 views

Carrier recovery with the Costas loop : PLL pull-in range

I have created a channel model in GNU Radio (a modified version of the default GNU Radio Channel Block). Its performance under AWGN (without timing, phase or frequency offsets) aligns properly with ...
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555 views

PLL phase and frequency characteristics

I'm currently working with BPSK carrier phase and frequency recovery in GNU Radio. I have been able to use Costas loop and Frequency locked loop (four carrier acquisition) which are based on the ...
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220 views

BER vs SNR simulation for GFSK modulation (Closed-form BER for GFSK)

I'm in the process of simulating the performance of a GFSK modem in GNU Radio. I have managed to get a curve similar to the curves I see in a number of literature sources. However, I need an accurate ...
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791 views

GNU Radio QPSK 4 Symbols

I'd like to generate a simple QPSK signal in GNU radio, but so far I haven't been able to get it to perform the way I'd like and I'm not sure if this has to do with some misunderstanding I have about ...
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Satellite receiver suite

I'm in the process of implementing a general purpose baseband system for modulation schemes (Linear + CPM) commonly used satellite and deep-space TT&C as shown in the functional flow block diagram ...
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322 views

Software Defined Radio samples analysis using gnuradio and python

I'm trying to replicate what gnuradio is doing in "pure" python with a hackrf. Having mixed result, I decided to use the same data to compare the outputs I obtain. My gnuradio workflow is the ...
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234 views

AM demodulation from a real RF signal

I'm capturing an RF signal transmitted at 433.8MHz, with a bandwidth of about 50KHz. My goal is to be able to save it as a .wav file. I'm using an RTL-SDR dongle and a software named HDSDR, where I ...
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USRP + GNU Radio as 1 GHz bandwidth spectrum analyzer

I have maybe not trivial but some interesting question. I need to create 802.11ac channels spectrum analyzer with USRP. Hardware: USRP B210 Software: GNU Radio 3.7.9 PC: Intel Core i3 i3210m 16 GB ...

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