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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Efficient frequency domain search for reduced number of hypotheses

In CDMA signals (such as GNSS) there are two unknown parameters when one receives the signal, residual carrier frequency and an unknown delay. Assuming the carrier frequency residual is known, what is ...
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How does the sample rate work on an SDR?

How can an SDR, which has a sample rate of about 32MHz record signals with a frequency of 1GHz? Shouldn't the sample rate be at least two times as high as the frequency or am i missing something?
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Research on SDR security Gnu Radio and legal transmission with filters

In fact, I am doing research around SDR and possible dangers. Then I stumbled upon the most well known "replay attack". Via Black hills, I came across the following diagram in gnuradio: The ...
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Why aren't I getting my expected FM channel when multiplying these two frequencies?

Hope y'all are doing well. Recently I've picked up a LimeSDR and interfacing it with GNURadio and been having a blast with it. I got my first FM receiever demo working using examples from LimeSDR FM ...
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G3RUH Multiplicative scrambler in C++

I have written and tested a G3RUH (1 + X^12 + X^17) descrambler. It seems to work quite well in an SDR project I'm working on. I'm currently working on a scrambler and I can't get it to work. Below is ...
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Sampling rate for a 200 kHz signal

I'm using a rsp1 to sample the output of an underwater acoustic transducer which has a resonant frequency of 200 kHz (with a 500 Hz bandwidth) . The transmitted signal is a CW pulse which can vary ...
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What a SDR can (and cannot) tell about a received signal's power/energy

I'm rather new to SDR and I'm still wrapping my head around understanding how it functions. I greatly appreciate it if you guys can help me understand what's going on. From what I've gathered, an SDR ...
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How does SDRs implement anti-aliasing filters, when the sampling rate can be fairly arbitrary?

I was looking at the schematic for the small USRP B205-mini SDR from Ettus. I can't seem to find any switchable analog anti-aliasing filter on the input of the chip, or anything resembling a filter ...
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USRP N210 Main clock rate and The transmission signal Sampling Rate

I am testing the transmission and receiving signal using two USRP N210. The communication setting as follows: ...
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How does under sampling modify the spectrum of a signal in nyquist zones and BW?

I have two conflicting concepts when looking at the spectrum of a analog to digital signal that has been sampled. The nyquist zones. So any sampling frequency fs will make the spectrum replicate at ...
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Can 2 (coherent) digitizers with input bandwith X be used to digitize a signal of banwidth 2X?

TL;DR: Can 2 tunable digitizers, each with an instantaneous bandwidth of X MHz and a common clock source, be used to achieve an instantaneous bandwidth of close to 2*X MHz by tuning their central ...
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How to judge the percentage of white noise and color noise when using typical SDR enviroment?

Per this question,I understand different result when noise occurs in time domain and frequency domain. As to the system,has antenna+upconveter+USRPB210+laptop,...
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More Efficient Frequency Shift + FIR Decimation

I am dealing with complex IQ data from a software defined radio. I'd like to digitally shift the spectrum by some amount to center an off-center signal, then decimate down to that signal only. ...
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time division duplexing (TDD) with USRP B2xx

I am going to implement a real-time TDD link (in the order of one-millisecond burst durations) using two laptops and two USRP B2xx (in either single antenna or dual-antenna ways). I searched a lot on ...
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GNU Radio and USRP audio source problem

I have a modem which accepts a voice in GNU Radio, digitizes and compresses it (codec2) and transmits it using USRP on one laptop and receives it on another laptop. When I use "Wave File Source&...
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GNURadio GFSK demod missing data

we are trying to develop a flowgraph for cubesat operation. Our flowgraph for includes both downlink and uplink parts in one flowgraph. It uses SoapySDR as a driver of an SDR. Most of the used blocks ...
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HackRF setup for capturing GNSS signals

I have a MATLAB script which process IF signals to acquire GPS satellites. I decided to capture IF signals containing GPS L1 C/A (1575.42 MHz) myself. What I have: HackRF TCXO for HackRF Active GPS ...
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GNU Radio, Frequency Hopping Spread Spectrum for High Hopping Intervals

I am planning to implement a frequency hopping spread spectrum transmitter and receiver in GNU Radio. In my project, the bandwidth of the message signal is around 200 kHz and the maximum frequency ...
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transmit signal with hackrf one

I want to use hackrf one to transmit a continuous signal. my question is that "can hackrf transmit signal continuously or it has certain interrupt between its transmission?" my question is ...
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Are Software Defined Radios only Oscilloscopes?

I am wondering if SDRs (software defined radios), e.g. HackRF, RTL-SDR, or USRPs, are, in essence, just oscilloscopes you can plug to a computer to get the data from it. If not, what are the main ...
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UBX could not transmit signal

I am new to x310. I want to transmit a signal with its UBX daughter board and using gnu USRP sink block . but it seems no signal transmitted. Is this a software problem or hardware?
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Computing Phase Difference Between Two Channels from SDR

I'm trying to compute the phase difference between two channels of a software-defined radio. I'm providing code for two different methods that I'm trying below. In both cases, I'm transmitting a pure ...
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Relationship between sampling rate and bandwidth in gnu radio

I wondering something. While working with adalm pluto sdr in gnu radio, the sample rate I enter in the source block is actually bandwidth. I know that bandwidth must be half of the sampling rate ...
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wireless card in place of an antenna/ hack a robot

My nephew has this toy robot and asked me to build a new remote for it. It's a "Cady Wida" robot from JJRC. When I opened it up, a tag inside said "40 MHz" and the board sported a &...
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LTEcellSearch on ADALM PLUTO error

Im following the example from Matlab in here https://www.youtube.com/watch?v=lcCWTnmKblE im trying to capture an LTE frame and decode the cell id, however i get a false PCI and it changes value ...
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Real-time FM demod results in clicking and strangely-shaped output

hardware engineer here dipping his toes into software DSP and running into some issues. I'm attempting to demodulate in realtime a simple narrowband FM signal with samples from an RTL-SDR, and play ...
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Changing sampling frequency of SDR

Here is the block diagram for RTL-SDR which is taken from Software-Defined Radio Using MATLAB, Simulink, and the RTL-SDR: I think it well explains the basics of RTL-SDR but I have multiple questions. ...
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Comparing self-made O-QPSK signal with Zigbee burst (Q-QPSK acc. to IEEE 802.15.4)

What might be the cause of the worse baseband demodulation result of the bottom VSA screenshot compared to the demodulation result shown in the top screenshot ? Randomized Q-QPSK signal generated by ...
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GnuRadio additive scrambling/descrambling

How are you supposed to use GNU Radio additive scrambler block? The wiki documentation is very vague on the subject: Scramble an input stream using a Linear Feedback Shift Register (LFSR). This block ...
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SDR and amplitude modulated signals

Can I view every signal that has been transmitted using software defined radio as a amplitude modulated signal? For example I could make a frequency modulated baseband signal in GNU Radio and connect ...
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SDR : IQ GMSK signal demodulation

I'm trying to develop an application for the demodulation of some GMSK signals transmitted over the air. I'm using a RTL-SDR which outputs 8 bits IQ samples of the baseband signal. Here is what I've ...
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Digital demodulator (SDR) for receiving legacy analog modulated wave

I understand that in SDR, after the ADC the signal processing is fundamentally based on I/Q modulated waves where any discrete value that can be transmitted corresponds to a symbol which is ...
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Doubt about sampling rate and spectrum with USRP and gnuradio [duplicate]

I have started working recently with software defined radio (SDR) as well as gnuradio. I have worked with digital signal processing for a while and one feature at one tutorial, which I saw for ...
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TypeError: primitive_connect() when executing in gnu radio

I'm building the frequency analyzer for RTL-SDR. But having problem in building and executing code. ...
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Can I create my IF signal on SDR before bringing data to PC?

I'm relatively new to SDR's and I'm trying to determine what sort of BW I need for my laptop to get the best resolution possible for an FMCW system. I have an X310 Ettus with a UBX160 daughtercard ...
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Why I get another spectrum when upconvert an o-qpsk baseband signal with a bladerf compared to a hackrf device?

I have just start working with bladerf instead of former used hackrf hardware and I need to solve a problem. Currently I use the following bladerf hardware, libraries and firmware: bladerf (2.0 micro ...
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Implementation of Overlap Save Filtering with Decimation

I am trying to implement Matlab code which performs FIR filtering with complex bandpass filter using Overlap Save method and perform decimation as well by using different length forward and inverse ...
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Code Snippet to Convert ADC Samples to I/Q

I'd like to pull a narrowband signal out of ADC samples, where the ADC rate is much higher than the bandwidth/central frequency of the narrowband signal. I'd like to feed the narrowband signal into a ...
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Unstable frequency/phase when using external reference for Ettus B200

I am attempting to do a simple record of a CW, 250MHz signal at the Rx port of an Ettus B200 using an Anritsu MG369 signal generator. I am using the 10 MHz ref signal provided by the SG (output @ ~...
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How is the Tx/Rx Gain calculated in USRP?

I know that USRPs are uncalibrated devices. In many exampls you can set the so called Tx or Rx gain (as in the picture below). Now, I know that this does not correspond to the real power of the ...
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Need to extract phase of incoming signal, how to find FFT bin of frequency of interest in GNU Radio?

When receiving a higher frequency signal, say 2 GHz, the freq as shown in frequency sink is often off by some amount (1-2 MHz) on the ettus B200. So I can't just assume the location of the signal is ...
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filter single radio station with sdr [closed]

I want to write a program to filter a single radio station using SDR. Not for any application just a stepping stone to learn. I am going to use C so it is easier for me to see the steps and things ...
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2 votes
4 answers
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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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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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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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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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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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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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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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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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