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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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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1answer
34 views
Max frequency of cosine in SDR
I would like to transmit a 56 MHz real cosine and receive it using SDR with max complex sample rate equals 61.44MSPS and an analog filter with BW = 56MHz (the transceiver is AD9361). Can I do it? How ...
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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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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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2answers
46 views
Transmitting a 350 MHz signal
I'm currently on an SDR kick and reverse engineering and then emulating all of the remote controls in my house. There are numerous solutions to transmitting signals over 315 or 433 MHz and you can ...
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2answers
72 views
DAC and ADC architecture in SDRs
What are the DAC and ADC architectures in SDRs for inphase and quadrature phase channels?
Do we have separate ADC and DAC for each channel or there is some clever way that they are multiplexed to ...
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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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26 views
Possibilities to get the amplitude of a signal at specific frequency from IQ
I'm newbie to the dsp topic and my understanding of math symbols is limited.
So at the moment I'm little bit lost to find the right resources.
I receive an IQ stream from a SDR.
Sample rate: 250k/s
...
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1answer
12 views
Converting PLL Discriminator into Doppler error
I'm writing a GPS receiver SDR software, and I have calculated the PLL discriminator ouptut as atan(Q_Prompt,I_Prompt)
I would like to know the formula that converts the discrminator output to doppler ...
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59 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:
...
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1answer
229 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 ...
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1answer
70 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
52 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
57 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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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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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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79 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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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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1answer
310 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
67 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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455 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
47 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
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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2answers
166 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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461 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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89 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
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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94 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
142 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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5answers
197 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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54 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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251 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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77 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
70 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
311 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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161 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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28 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
356 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
261 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
86 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
107 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
142 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
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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366 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
75 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
848 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). ...
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1answer
88 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
2k 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 ...
