Signal Processing

Questions tagged [sdr]

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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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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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40 views

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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44 views

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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124 views

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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48 views

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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202 views

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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55 views

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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72 views

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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27 views

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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56 views

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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150 views

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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34 views

Spectrum Visualization of TX AD9361 Simulink Model

I'm using the SIMULINK AD9361 simrf support models, more specifically i use an AD931 TX model to generate a 20MHz RF LTE signal around 2GHz Fc the issue is when i use a spectrum analyzer scope i see ...
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646 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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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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80 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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79 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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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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49 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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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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94 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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56 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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124 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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64 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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957 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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204 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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112 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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176 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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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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34 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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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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23 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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66 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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845 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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141 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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129 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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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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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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194 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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246 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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571 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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77 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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