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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211 views

What can be done with I/Q data which would otherwise be impossible?

As I understand it, I/Q data is the complex representation of any waveform. It enables us to understand two things at any arbitrary point in time: The projected amplitude of the waveform. The ...
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1answer
29 views

How to modulate PSK63 with liquiddsp?

I am trying to implement the BPSK-63 modulator using liuid dsp library. Here is my code: ...
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0answers
27 views

Finding time of arrival of signal using GNU radio

I am sending a repeating BPSK modulated PN sequence signal from a USRP x310 transmitter. I am receiving the sequence with another USRP x310. Both are attached to an octoclock. Is there a way to get ...
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18 views

RTL-SDR GNURadio FM Radio

LINK to video rtl sdr video using gnuradio for fm radio. shows signal stages thru the blocks
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1answer
27 views

Detect static in audio with Python

I have a program running in python. It samples the demodulated FM output from an SDR. When there is no transmission, the input to the program is completely static. How can I go about squelching the ...
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1answer
37 views

SDR Dongle, 2MHz Bandwidth related to Fs but bandwidth range 50-2000 MHz

Having a conceptional issue. If a SDR dongle has a 2MHz signal bandwidth, but that can be anywhere within the range of 50-2000 MHz, why is the bandwidth only 2 MHz. The clock must be double the ...
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1answer
21 views

Heterodyne modeling confusion in SDR

I've been reading this lab sheet which explains the signal processing math of the RTL-SDR radio dongle. http://www.eas.uccs.edu/~mwickert/ece4670/lecture_notes/Lab6.pdf In pages 5 and 6, the local ...
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36 views

ADALM-PLUTO SDR with gnuradio on Macbook

I am looking to interface PlutoSDR with gnuradio on a macbook. I have gnuradio-companion installed, however, plutosdr blocks (source and sink) don't show up in it. Also tried installing iio-...
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1answer
46 views

Processing Wifi Packets

Im trying to use GNUradio 3.8 with an sdr to pick up some wifi packets 2.4 and 5 GHz but im seeing a ton of dropped samples from my sdr. Im wondering if my dropped samples have to do with the sample ...
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1answer
46 views

Cosine of amplitude 1 but GNU Radio shows FFT has amplitude > 30,000

I am doing an FFT on a cosine wave which has an amplitude of 1. The FFT is amplitude is not 1 but over 30,000. What am I missing here? It's from the GNU Radio FFT wiki page:
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50 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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1answer
38 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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138 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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61 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
50 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
77 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
46 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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2answers
25 views

In SDR could you isolate I and Q

I'm just curious if this could be a way of transmitting stereo?
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1answer
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
13 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
293 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
74 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
62 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
61 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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82 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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92 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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104 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
338 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
69 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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537 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
49 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
174 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
485 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
98 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
220 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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99 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
162 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
209 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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56 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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266 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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84 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
78 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
332 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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189 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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37 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
384 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 ...