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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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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1answer
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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1answer
68 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
549 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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577 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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1answer
808 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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1answer
279 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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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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73 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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456 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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1answer
306 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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How does transition width of a low-pass filter affect a message which is well within the pass-band?

I'm taking a communication systems course and we use GNURadio in the lab. In an exam, we had a simple question where we were asked to demodulate a Dual Side Band (with carrier) AM signal in GNURadio. ...
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856 views

gnuradio: How can I change the value of the tag exiting the “Correlate Access Code - Tag” block?

Background: I have built a conventional demodulator in gnuradio and am trying to send payload data out of the flowgraph to an external Python script. I'm using gnuradio v3.7.12. It seems to me that ...
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472 views

GNURadio Sending Short Packets

I'm trying to create a basic GNURadio flow graph that will transmit a short message in order to receive an appropriate reply back. I currently have the following flowgraph: I have a program that ...
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1answer
4k views

How do I extract data from a gnuradio flowgraph now that the message sinks have been deprecated?

Background: I am writing a Python script that contains a gnuradio flowgraph object used to demodulate incoming IQ data. The flowgraph is started and runs while I periodically poll it for demodulated ...
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1answer
125 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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1answer
574 views

What kind of modulation is this?

I'm trying to find out what kind of modulation and encoding is used by my window cover remote control, aiming to implement the same on a Raspberry Pi to add a bit of home automation. A colleague ...
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1answer
965 views

Avoiding DC spike while decoding FSK signal

I am using the Quadrature Demod module in GNU Radio to decode an FSK signal, but the signal is appearing quite noisy. It has two distinct peaks centered around the advertised frequency, but they are ...
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2answers
644 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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256 views

how can i use gr-specest in gnuradio? [closed]

hello Pr how can i use the fam and the gr-specest in the GRC for cyclostationary features ------------------------------------------------------------------------
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214 views

Unable to stabilize 8-PSK signal with self designed costas loop

I am trying to make a signal processing block which implements the costas loop to stabilize an 8-PSK signal. Here is the flowgraph with "costas_loop" being my block. My workflow is the following - <...
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426 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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1answer
104 views

Frequency components much less prominent at the receiver for multiple tones

I am trying to transmit a multi-tone signal from one USRP (N210) to another and have written an out of tree block to generate the multi tone signals using an ifft. The two USRPs are connected directly ...
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278 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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1answer
892 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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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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2answers
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
309 views

Denoising effect in GnuRadio OFDM Serializer block

Why does the OFDM serializer has such a strong denoising effect in the flow graph below ? Is that normal ? The upper constellation is AFTER the OFDM serializer block and the lower is BEFORE the OFDM ...
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1answer
4k views

Large spike at the center frequency when using Ettus X310

I am using the Ettus X310 SDR and GNU radio. On the GNU radio schema I have a standard UHD USRP source block connected to a GUI FFT sink - basically I'm just displaying the spectrum of the raw signal ...
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1answer
536 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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1answer
408 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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1answer
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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289 views

Is GNU Radio a good choice still? [closed]

I'm a newbie at DSP. I am starting a hobbyist project where I plan to monitor 100's of wildlife radio collar frequencies (at my job) and record how many "beeps" per minute are received. My software ...
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385 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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2answers
838 views

Sampling frequency lower than half of sampled signal frequency?

In GNURADIO when RTL-SDR Source block is placed there is a parameter Sample Rate (sps) and ...
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1answer
4k views

GNU Radio - PSK Mod block - unexpected constellation diagram

I am simulating a QPSK modulation in GNU radio. Here is the flowgraph: . The source is a binary stream coming from the Random Source block. There are 4 PSK Mod blocks configured identically (4 ...
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1answer
2k 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
4k views

Why isn't this AM Demod GNU Radio flow graph working with different sampling rates?

I am trying to demodulate an AM signal in GNU Radio, and I am having problems with the sampling rates. I will start off with an example where the flow graph was working. The sampling rate is 256kHz, ...
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1answer
162 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 ...