Questions tagged [sdr]
Software Defined Radio (SDR) is the implementation of radio receiver, detector and transmitter systems in software, as opposed to analog hardware or application-specific ICs. It usually uses a baseband sampled representation of the RF bandpass signals.
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58 views
PLL in Tracking for GNSS behaviour
I'm doing work on SDR for GNSS and I'm tracking the signals I/Q using PLL.
The calculations for the PLL is done like the following for error estimation:
...
3
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1answer
127 views
Obtain I/Q Components from a Real Signal On the Fly - Hilbert Transform or Digital Downconversion?
I'm planning to build a data acquisition system for a software-defined radio receiver. Basically, it just uses an ADC which samples an analog signal and send the signal to a processor. And then a ...
3
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1answer
61 views
I Q sampling and baseband version of analytic signal
Is it correct to say that if we have a radio signal $s(t)$ centered around the angular frequency of $\omega$ as $\omega\pm\omega_B/2$ (where $\omega_B$ is the bandwidth of the signal) and the ...
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1answer
27 views
Generating band-limited NRZ signal
What is the bandwidth of a NRZ signal (of a given frequency) and how would you directly synthesize a discrete version a band-limited NRZ signal at some higher sample rate?
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1answer
44 views
SDR spectrum anomalies
Is it normal to see periodic peaks going from 48.75 - 90 MHz? Also i was checking on my SDR dongle once and the whole band was raised above background offset for like a whole 50 MHz bandwidth and then ...
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45 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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7 views
Simultaneous transmission of a D2D user
Can a D2D user (a device) transmit simultaneous different signals to a cellular user and a D2D receiver. If we suppose that the D2D device is equipped with SDR technology and can change their ...
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45 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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63 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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1answer
226 views
Digital FM Demodulation
I have created a Common Lisp Library to receive samples of an FM signal from BladeRF1 SDR. I want to write a subroutine to implement FM demodulation. The input should be in the format of IQ data.
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1answer
49 views
Recommended device for testing my own SDR?
I'm trying to implement my own SDR using Matlab. I was wondering what kind of device I could buy in order to test it. I know I can use my own soundcard but I was thinking of EM waves, not sound. Is ...
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60 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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318 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
42 views
Equalisation of FFT spectra
The image shows the frequency spectra of a signal recorded using a SDR. The SDR is of DirectDownSampling type and has some compensation in the signal chain to compensate for the DC spike which would ...
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1answer
34 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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2answers
142 views
Getting the bitstream of an unknown RF signal
I am trying to get the bitstream of a signal sent over 433MHz. I have installed SDR# (I'm on Windows), connected my NESDR SMART, and I identified the signal here:
I can see there is only one peak ...
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1answer
391 views
How to process IQ data saved as a binary file using rtl-sdr? [duplicate]
How to get meaningful insights from IQ data saved as binary file?
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1answer
79 views
Recommendations for SINAD equipment
I am interested in buying a device that measures the SINAD of the audio signal(FM signal) that I receive from PC.
Here is the setup:
Signal generator (generating 1kHz FM signal ) $\rightarrow$ ...
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21 views
Any recommendations for buying SINAD measuring equipment? [duplicate]
I am interested in buying a device that measures the SINAD of the audio signal(FM signal) that I receive from PC. Here is the setup :
Signal generator -> attenuator ->HackRF connected to PC with SDR#
...
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1answer
161 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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0answers
88 views
Which equipment to use for testing performance of AM, FM, and DAB
I want to test the performance of AM, FM and DAB radio in RTL-SDR. I want to measure sensitivity, adjacent channel selectivity, cross-modulation/blocking, and third-order intermodulation to be some of ...
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1answer
106 views
Appropriate channel bandwidth for my BPSK modulated Psuedo-Random code on direct conversion transceiver
My hardware is an analog device SDR+Xilinx FPGA (sdr = fmcomms4-ebz). The direct conversion transceiver (ad9364) has a tunable channel bandwidth of 200Khz - 56Mhz. I am employing BPSK modulation on a ...
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4answers
157 views
Detecting a three-tone signal in real-time
I'm new to digital signal processing, and I've been looking into FFT, filtering, Matlab etc. What I'd like is to build a program which will detect when a certain BEEP is transmitted through a trunked ...
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46 views
what waveform using to send qpsk signal with IQ tranceiver
I have an SDR tranceiver (AD9361 on fmcomms3) working with IQ channels, i wanted to make a c++ software that modulate and send a digital QPSK signal but i'm a beginner in digital signal processing and ...
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226 views
How to plot real time graph using python for the signals received from RTL SDR?
Using the below python code, I am able to plot a graph. Can anyone please tell me how to modify this code to plot the graph continuously in real time?
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59 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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1answer
64 views
How do I differentiate between signals from an unknown program?
I believe this question is on topic for this site under Algorithm debugging questions, but if not, I would appreciate a suggestion about where to post this question....
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2answers
259 views
From IQ to pi/4 DQPSK
I need to decode $\frac\pi4$-DQPSK packets from an SDR, preferably in C#.
I have the SDR receiver part done. Now I'm trying to learn how to take the IQ stream and get the packet info from it.
I've ...
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0answers
125 views
Why do IQ Impairements, Quadrature Skew and DC offset have these geometric effects on the constellation?
I'm studying telecommunications, and would like to be sure to understand the maths behind these effects.
For IQ Imbalance and DC offset, it seems pretty clear why we observe a rectangle shape or a ...
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0answers
21 views
Correct way to calibrate RX into a measuring receiver
While playing with my SDR (Software Defined Radio) Board, I was interested in performing a TX output power table at different center frequencies and TX antenna gains.
I have an RF frequency generator....
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1answer
288 views
90 Degree Phase Shift / Rotation Algorithm for SDR
I'm working on a library to preform frequency demodulation from an SDR signal. I'm using https://github.com/sysrun/rtl-sdr/blob/master/src/rtl_fm.c as a crib for this. The algorithm starts by taking ...
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1answer
222 views
Best way to resample an OFDM signal without interpolating + filtering?
I am working on a custom transceiver with a sampling rate of 3.84 MHz (256 OFDM subcarriers at 15 kHz, although 56 subcarriers are null). I would like to resample the signal to 5 MHz, in order to use ...
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1answer
81 views
Compare the quality of IQ data from different Software Defined Radios (SDRs)
I want to know what methods are best to scientifically evaluate the quality of different Software Defined Radios (SDRs) that spit out IQ samples.
For this question, I would like to set the boundary ...
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1answer
96 views
Using Matlab/Simulink to build Reader based on Software Define Radio
I am a student. I want to learn about Software Defined Radio to build a Reader for Saw tag and simulate them on Matlab/Simulink.
These bocks below is what I want to build in Matlab/Simulink
I found ...
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1answer
107 views
Modulating ofdm in audio spectrum
Trying to modulate audio with OFDM data.
My fs = 44.1khz, i'm using 64 sub-carriers, but i'm only using 5 sub-carriers for data, so my bandwidth is about 3.445khz. I'm not sure how to properly write ...
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1answer
210 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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1answer
335 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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1answer
65 views
why transmitting a long pulse its spectrum gets spread?
I'm transmitting an RF signal with a CC1101 at 440 MHz.
This signal is a constant of 1, so the spectrum should be a delta.
Using a SDR dongle, I've checked the spectrum and it's wider than a delta ...
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2answers
749 views
Time Alignment of 2 Sensors Sampling the Same Signal with Different Hardware Delays
I have two radios sampling simultaneously, and I am trying to time-align their two signals (they will always start sampling at slightly different times with random delays due to hardware differences). ...
3
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1answer
81 views
How to undo dynamic Doppler effect by software?
I have a signal affected by Doppler effect. In general, the Doppler effect changes the scale of the time and frequency domains. So, to undo this phenomenon, I am using a sampling rate converter. Two ...
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1answer
1k views
Checking for VHF pulse with SDR and python
So I have a small NooElec Software Defined Radio and I've got it working well with my Raspberry Pi using GQRX as a controller and to visualize the SDR output.
My goal though is to use a python script ...
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0answers
547 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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0answers
93 views
Does anyone recognize this modulation?
I'm trying to extract the code of my garage remote, but i have some difficulty to find witch modulation has been used.
At first I thought it was a simple digital modulation, but there is some strange ...
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2answers
2k views
Help in understanding the IQ raw file format used by SDRs/GnuRadio [closed]
I apologise as I feel like I should know this off the top of my head. I will try to explain what I believe I know and then ask a simple question.
The usual file format used in software defined radios ...
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1answer
393 views
How to get coordinates of complex RTL-SDR signal?
As I have already explained here (https://stackoverflow.com/questions/49358449/python-how-to-get-coordinates-of-complex-rtl-sdr-signal-peaks?noredirect=1#comment85722604_49358449), I need to find the ...
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1answer
121 views
Understanding unexpected i/q calculation on a downsampled signal
I am reading samples with an RTL-SDR, centered on an FM broadcast station:
...
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211 views
RTL-SDR data types
I am using pyrtlsdr to read samples from an RTL-SDR. As in the example on the page, I am getting samples with sdr.read_samples(x).
The RTL-SDR returns 16 bits per ...
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1answer
88 views
FFT showing evenly spaced signals when tuned to ~56 MHz down to 25.680
I'm running GQRX on Mac OS X 10.11.6 hooked up to an RTL-SDR dongle. I noticed when I'm tuned anywhere between ~56 MHz on down to 25.680 MHz I see evenly spaced signals on the FFT. But when I tune ...
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2answers
581 views
Curved noise floor and ugly unexplained peaks after FFT
It has been so long since I studied this at University, so I'll better ask here if I'm doing something really wrong here.
I'm using a USRP frontend for L1 band surveillance. I want a 20MHz bandwidth, ...
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1answer
133 views
Weird noise floor slope when capturing with USRP E310
I'm experiencing a weird effect on my captures. It may just be due to my bad dsp understanding.
I'm using an E310 SDR platform to capture a multitone (4 carriers) signal:
Fc = 150 MHz
Bw = 286 KHz
...
