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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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417 views

How can I perform timing recovery from the envelope of PSK signals?

I'm trying to reimplement FDMDV in GNU Radio, largely for educational purposes. It consists of 15 PSK subcarriers, 75 Hz apart, 50 symbols/sec each. The center one is BPSK and alternates phase each ...
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277 views

Time recovery - GNU Radio

I read about Time recovery (as an example, the Mueller&Muller algorithm); it is linked to when you should sample your signal. I am currently working on a project with GNU Radio and there is ...
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366 views

Moving signal power normalization

I am using matched filters using GNU Radio to extract from noise a CW Morse signal. The filter actually performs pretty well in various SNR environments. My problem is that the threshold upon I decide ...
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1answer
1k views

Possible to Derive Receive Signal Power from RSSI?

My Set-Up I am sending packets at a specific frequency and with a specific gain from one N-210 USRP to another of the same model. NOTE: I have the transmitting USRP connected to a series of ...
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1answer
118 views

Better way to mute fundamental baseband frequency?

I'm working on a project to monitor the fluctuations and harmonics present on standard 120VAC mains power. I built an adapter that drops the voltage from 120VAC to 12V and then down to 0.5-0.6 VAC ...
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2k views

OFDM symbol acquisition block in GNU Radio gives rotating constellation even if there is no carrier offset. How is this possible?

Why does the constellation rotate when using OFDM Symbol Acquisition block in this flow graph below ? The only explanation I could think of would be carrier frequency offset but in this flowgraph ...
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1answer
93 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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2answers
597 views

Use GNU Radio to extract information from a VOR signal

I want to design a GNU Radio project to extract the information of a VOR signal, then find the angle to the north and the Morse code of the station. Is there any example that shows how to do it?
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64 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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1answer
94 views

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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1answer
263 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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1k views

FFT plot in GNU Radio

i got similar question as in FFT scaling in GNU Radio and quite not clear about the answer given so far. I understood that the FFT plot is a relative value in which we have to use measurement ...
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1answer
1k views

GnuRadio: Clock Recovery MM: imu out of bounds

I have created a flowgraph, based on an example of Michael Ossmann, which takes in a signal, and should output bits. I need to use the clock recovery MM block, which I do not fully understand yet. ...
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1answer
157 views

How to manipulate attenuation in Parks MClellan algorithm?

I am using GNU Radio C++ source code in my app (pm_remez()) for generating FIR filters coefficients. Input parameters here are: ...
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1answer
2k views

FFT scaling in GNU Radio

In GNU Radio Companion, I have created a very simple flow graph where I generate a 1 kHz, 2.0 volts peak-to-peak sine wave, and feed it into an FFT sink and a time domain sink. The reference dB in ...
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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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32 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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25 views

Over-the-air (OTA) BER measurement

I'm in the process of evaluating BER performance for a GNU Radio BPSK receiver. The setup for the experiment is illustrated below. Using a spectrum analyzer just before the USRP, the average channel ...
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53 views

Auto correlation , Time duration measurement for SDR calculation purposes

I'm a SDR and DSP beginner , I'm trying to find correlation between pulses I receive using a SDR, with a replica that I have (basically pulses with predetermined duration's). I've looked in this ...
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68 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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1answer
35 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
27 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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36 views

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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35 views

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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37 views

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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36 views

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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107 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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72 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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61 views

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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39 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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1answer
160 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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70 views

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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1answer
522 views

Practical diversity combining at receivers (Maximal Ratio Combining & Equal Gain Combining)

I am trying to perform practical diversity combining implemented in GNU Radio by using Ettus N210 USRPs, one as a transmitter and two as receivers. To compare Equal Gain Combining (EGC) and Maximal ...
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402 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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2answers
1k 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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1answer
66 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
283 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 ...