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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Phase difference calculation for non divisible sample rate to frequency

I am learning DSP and I am trying to simulate a simple phase difference calculator between two sinusoidal signals using GNU radio. My flowchart looks like this: As can be seen on the chart, one of ...
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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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447 views

How to set a Carrier Wave for DBPSK Modulators in gnuradio?

for a Project I need to build an Audio Modem in GNU Radio. I decided, that it would be the best to use DBPSK Modulation, because that is fast and relatively noise resistant. But as it seems, the ...
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307 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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16 views

Slip rate for sliding correlator channel sounder in GNU radio

I have a spread spectrum channel sounder running the following transmitter and receiver: [![tx][1]][1] [![enter image description here][2]][2] Imm not sure how to modify the slip rate between the ...
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28 views

Extracting rms delay, delay spread, and CIR from power delay profile

I have a spread spectrum channel sounder running the following transmitter and receiver: When running it over the air (~2km), I get the plot of the correlator output: I can see that there are peaks ...
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42 views

Synchronization of tx and rx in sdr

I am implementing a FMCW radar using bladerf sdr: When reading the output from the vector sinks, the outputs are not synchronised.How should I synchronise them? is it possible to do so using gnuradio ...
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79 views

Sample rates, Samples per Symbol, and Digital Pulse Shaping

Having some confusion about digital pulse shaping for complex baseband (passband) signals. The complex baseband linear modulation equation is $$s(t)=\sum_{m=-\infty}^{\infty}\text{Re}\{a_m\}h(t-mT)+j\...
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Gnuradio scaling on Ubuntu issue

I have problem with scaling on gnuradio. When i use more than one WX widget - which shows parameters of signal - i can't see last widget. How can I deal with this problem - just to scale scopes, and ...
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86 views

16 QAM GNU Radio

I have been trying to implement a transmitter receiver flow graph which uses 16 QAM. I am using a USRP B200 as the transmitter and a RTL-SDR as the receiver. I used uhd_packet_tx.grc and ...
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321 views

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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39 views

Gnu Radio Constellation Receiver

I am trying to use gnu radio to transmit data from one SDR to another using a 16QAM modulation scheme. This is the diagram on the receiver side. Looking at the constellation sink, the constellation ...
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322 views

How to adjust receiver gains to avoid saturation and quantization noise to optimise post digital processing?

I am using a Hack RF One as SDR and the software GNU Radio to receive and process signals emitted from a drone. Given that the drone is moving and is emitting signals from a wide zone, received signal ...
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1answer
243 views

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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31 views

Chunks to Symbols in Gnuradio 3.8

I am trying to follow this tutorial to build a flow graph with GnuRadio 3.8. However, I am unsure what settings should I use for Chunks to Symbols and get some errors when I execute the flow graph: <...
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GNU Radio | Packet Encoder/Decoder alternative

Are there any alternatives for packet encoder/decoder (deprecated) in gnuradio3.8.0.0 ?
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57 views

Record Signal after Threshold Reach in GNU Radio

I would like to use GNU radio to begin recording a predetermined number of complex samples to a file sink automatically as soon as a signal magnitude threshold is reached. For example, as the gnu ...
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1answer
34 views

GNU radio, FSK channel estimator

A quick question, is there any way to do channel estimation on a (G)FSK receiver. I'm trying to build a DASH7 receiver. I found that there is a block for a OFDM channel estimator, but i can't find ...
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639 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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167 views

Symbol Synchronization for GFSK/FSK signals in GNU Radio

I am trying to demodulate GFSK signal, and extract the packets using GNURadio. TX information: It is basically BLE transmission but customized. BW: 2MHz, data rate: 1MSymbols/sec, 1 bit per symbol. ...
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22 views

Increasing samples per symbol degrades correlation between signals

I am trying to implement a simple pseudo-noise (PN) ranging simulation. I have used this GNU Radio example, and I have adapted it a bit to suit my needs. Here is a screenshot of my flowchart: The ...
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1answer
42 views

How to correct for delays in a PAM-X signal with orthogonal CDMA?

I have a receiver which receives data bits at a rate of 5kbit/s. The number of data bits per burst is low (say, 16 bits). These databits are obtained after despreading the incoming signal using an ...
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2k views

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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473 views

I wish to create a GNU Radio program in C++ that doesn't need GRC or Python, is there a reference or template for this?

I want to create a functionally equivalent C++ file to the Python top_block.py file that is generated by GRC when executing a (blank example) flow chart. I know that C++ can be used to define blocks ...
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36 views

Strange signals in wifi channel

I am currently working with a USRP B200 mini-i to receive 802.11 signals from various usb wifi devices. When sending packets with the USB device over a channel, lets say 2.412GHz, i can't really see ...
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104 views

Proper way to detect and decode transmission in gnuradio

I am receiving AM modulated data over USRP. I successfully receive the data using an IF frequency (i.e., offset from the carrier), apply a highpass to remove RXLO phase noise and then downmodulate the ...
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67 views

How to architect a “for loop” (frequency hopping) in gnuradio (companion)?

I have the setup where I send data via USRP Sink over an SDR and receive the response. However, this needs to be performed at different carrier frequencies, sequentially in time but continuously (the ...
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78 views

gnuradio extremely sluggish with QT (but seems OK with WX)

I am evaluating gnuradio with Ettus USRP X310 and 2xUBX-160 daugterboards, connected via GBit ethernet to a new Lenovo laptop running Win10 and gnuradio 3.7.13.5. I am testing it with the most basic ...
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149 views

GNU Radio - Bandwidth and Band Reject Filter

I am currently trying to generate a psk modulated carrier with gnu radio. Attach is an image of my flow graph. As can be seen I am generating a bit stream using the Random Source module and ...
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68 views

OQPSK - GNU Radio Companion

I was wondering if anyone has had any success in implementing OQPSK in gnuradio. I have a working theory of expanding on the Constellation Modulator to include a custom OQPSK function. I have ...
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91 views

RSP1A sample rate vs if bandwidth

I'm using the RSP1A SDR and I want to understand how to choose the best configuration for receiving a signal of 125 khz bandwidth. I would like to know if when choosing the option 200 KHz IF ...
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48 views

GNU Radio - General Filtering Questions - Any feedback is appreciated!

This is a fairly general question I feel like. So, the scenario I am presenting is this: I am generating random data using the random source module and feeding that data into the Constellation ...
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1answer
251 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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104 views

How to setup filters to catch 4FSK deviations

I'm trying to demodulate a radio signal from Motorol DP4801 (MOTOTRBO) that follows DMR specification. I'm receiving the signal by using HackRF with the rate sample 1 MHz. The radio uses frequency ...
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36 views

GNU Radio | Grouping just 24 consecutive soft bits from a repeating tagged stream onto 3 bytes, starting from a specified tag

A vector source [0,1,0,0,0,0,0,0,0,1,0,0,0,0,0,0,0,1,0,0,0,0,0,0,0,1,1,1,1,1,1] produces repeatedly a tagged stream with one tag, ...
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116 views

Having trouble transmitting/receiving a BPSK signal using two USRPs

I am relatively new to working with SDRs and GNURadio and I am attempting to generate a BPSK signal and transmit it through one USRP and receive and demodulate it on another USRP. I am using GNURadio ...
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1answer
991 views

O-QPSK constellation interpretation - GNU Radio

I am currently trying to recover the I&Q of a O-QPSK signal generate from the standard XBEE arduino module using a B200. I can get somehow get a "look-like" of a constellation. Here an screenshoot:...
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452 views

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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204 views

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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855 views

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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1answer
220 views

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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1answer
115 views

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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1answer
38 views

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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1answer
152 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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1answer
201 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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1answer
578 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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1answer
473 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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85 views

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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1answer
1k views

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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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 ...