Questions tagged [synchronization]
The synchronization tag has no usage guidance.
99
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QPSK demodulation carrier frequency offset compensation on python
I am new to signal processing and I am trying to demodulate the IQ data, and I am stuck on the carrier frequency offset compensation.
I has 1000 samples and it is 1MHz data.
For the general idea, I ...
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What's the difference between frequency shift, frequency offset, phase offset, and phase noise?
I'm confused about these terms: frequency shift, frequency offset, phase offset, and phase noise. My understanding that frequency shift and frequency offset are the same and caused by Doppler shift. ...
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147
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Symbol synchronization interpolation control
Could anyone explain the action of interpolation control in symbol synchronization? What the underflows mean? And how it provides the fractional part? I know how other components work but don’t ...
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Baseband algortihms in exisitng mobile sytems
For OFDM-based systems, many algorithms and techniques have been proposed for each baseband functionality like synchronization and channel estimation. Do practical systems like mobiles employ only one ...
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300
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Find out time offset between two substantially same audio tracks
Say we have two audio tracks of the same movie but from different sources. The length of the animated logos at the beginning is different, so the actual movie audio starts slightly earlier on one ...
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Sampling Time Offset estimation for OFDM signal
I have a signal constituted by known OFDM symbols, and my goal is precisely estimate the Sampling Time Offset (STO). However, while the STO in the context of a single-carrier modulation is pretty ...
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Why are preambles repeated in communication systems
Many modern digital communication systems repeat a preamble at the start of a frame/burst which is used by the receiver for timing and frequency synchronization. One example is 802.11a. Why are the ...
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168
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Synchronizing two sets of data sampled at different frequencies
I have two different datasets.
Dataset 1 has a frequency of 1000Hz/sec and dataset 2 has a frequency of 50Hz/sec, how can I synchronize the two datasets so that they can be used as training data?
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114
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oQPSK symbol synchronization
I'm validating a C++ oQPSK receiver. The 5Mbps oQPSK signal is generated by a satellite emulator. The receiver structure goes as follows:
SDR --> AGC --> Costa's Loop --> Delay --> ...
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39
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Is there any sampling offset when using external reference signal
I perform real experimental tests for optical communications using DCO-OFDM. The transmitted signal is uploaded into an AWG (arbitrary waveform generator), then bias (2.5 V) is added before adopting ...
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Why should costas loop be done after clock recovery, as opposed to before?
In GNURadio's PSK tutorial they place the costas loop after clock sync and linear equalizer. This seems odd to me.
I'm thinking that it's easier to lock onto a carrier frequency at the higher RF ...
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146
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Problems with PSS phase offset calculation algorithm
I'm trying to implement a carrier frequency offset (CFO) estimation algorithm to correct my phase offset with the correlated PSS signal.
The algorithm for a corelated signal y(n) is as follows:
y(n) ...
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57
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synchronization algorithm for cpfsk modulation
I am searching for simple and efficient algorithm to implement in order to estimate the symbol timing offset for synchronization purpose
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37
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SDRs synchronization
I have 3 software defined radios (we can suppose that we have Ettus X310). I need to synchronize them because I need a high level of accuracy.
I know that I can use the Octoclock to synchronize them, ...
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74
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Synchronization for busty signals by correlation methods
I'm trying to reuse standard synchronization algorithms for phase(Costas) and Time (Polyphase Filter bank) for receiving bursty signals. The bursty signals are transmitted every 5 seconds. The signals ...
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Synchronizing 2 time series signals at slightly different sampling frequencies
I'm working with an embedded system that has two acquisition channels and unfortunately, their clock crystals are slightly out of sync. Even though both boards are configured by software to sample at ...
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Derivation of Costas Loop SNR in digital domain
The tracking performance of PLL-based is often expressed in terms of error variance. To take into account the effect of Loop bandwidth, another parameter, called loop SNR is used. Loop SNR for an ...
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180
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Costas Loop SNR
I've seen in literature that loop performance is inversely proportional to loop SNR. The higher the loop SNR, the lower the variance, the better the performance. My question is how do we calculate the ...
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125
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Frame synchronization for single carrier burst applications in fading channels
I recently started to implement communication systems with software-defined radios in GNU Radio. In my system design, I am planning to transmit data in burst mode, the frames will be not sequentially ...
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How can I fix bad clock recovery for bursts with short distance?
I use GNURadio as a prototyping tool to build a receiver for a digital signal of a home appliance. The signal itself looks good so far.
Also the symbol synchronization works well using the symbol ...
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3
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798
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Confused about the difference between frequency synchronization and phase synchronization
I am not sure if this is the correct place to ask this question but it looked like the most fitting SE site.
I study software engineering and I am taking a course about networking, where ...
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In OFDM, does the parameter time offset is important if there is only one mobile in the cell?
I am learning about OFDM, and in my reading, I have noticed that (mentioned everywhere) synchronization is a very critical aspect of OFDM. Here, I am writing in the context of time synchronization (...
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940
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Why is phase range between $-\pi$ and $+\pi$ (instead of $0$ and $2\pi$)?
I wonder why the phase range in DSP applications is between $-\pi$ and $+\pi$.
For example, why is that not between $0$ and $2\pi$?
This question popped when I was reading about synchronization in ...
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307
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Design a timing recovery algorithm with predefined samples with max amplitude
I need your help in understanding how to simulate a timing recovery algorithm. I have already read a lot of literature and posted here the question but I have still doubts how it works.
Let me briefly ...
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Band-edge timing error detector, time accumulator
im trying to implement a band-edge FLL and timing locked loop from this paper (https://www.researchgate.net/publication/261499267_Band_edge_filters_perform_non_data-...
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Correcting large frequency offsets at very low data rates
Consider a typical BPSK system running at a baud rate of 1 kbaud/sec - the receiver needs to deal with severe frequency offsets, let's say up to +/- 1 MHz offset and that the frequency offset can ...
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2
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155
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Symbol time offset simulation
I ran a number of simulations for symbol timing synchronization in the past. I used GNU Radio mainly. Now, I'm trying to do the same thing in C++. To achieve that, I need a way to introduce symbol ...
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1
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259
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Dealing with bias in an FFT for frequency correction
I'm working on using an FFT for frequency correction of a generic modulation signal. My algorithm basically attempts to balance the energy in the positive and negative frequencies of the FFT to be ...
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71
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Actual Sample Rate slightly off?
When capturing microphone audio, I noticed that my static buffer eventually overflows.
So I timed the samples, and low and behold I'm getting an actual sample rate of 44102-ish Hz (my timer is very ...
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329
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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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113
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aperiodic auto correlation properties
I'm reading about PSC (primary synchronization code) in UMTS. It is a so-called Golay sequence.
It is said it has a good aperiodic auto correlation properties.
What does it mean (in terms of aperiodic)...
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195
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Symbol synchronization with unknown symbol rate
I'm learning about the early late gate symbol synchronization and understand that it needs to be given the symbol rate ahead of time.
How could a multi-symbol rate system use an early late gate?
It is ...
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synchronize adcs with neuronal network
if i have two adcs(analog to digital converters) sampling a signal. Is it possible to synchronize the two adcs with deep learning?
as far as i know, with super-resolution on image processing it is the ...
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How to distinguish between received quadratures
How can you distinguish between two quadratures in QAM when the phase is not known at the receiver? For example, if the quadratures are sin and cos, how can the receiver tell which one is which, since ...
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Why does altering path length in radio transmission alter the phase of the received signal?
I do have a very naive yet bothering question:
Assume I send a sinusoid signal
\begin{equation}
A*cos(2\pi ft+ \phi_0)
\end{equation}
over a radio channel. Assume there is only a LOS-path for each ...
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Symbol Synchronization for GFSK/FSK signals in GNU Radio
I am trying to demodulate GFSK signal, and extract the packets using GNURadio.
TX information:
It is basically BLE transmission but customized. BW: 2MHz, data rate: 1MSymbols/sec, 1 bit per symbol. ...
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OFDM symbol synchronization
In an OFDM receiver, how could we find the start of the symbol for FFT operation.
I know the CP-based method to find the start of symbol. However, what if the sampling is off by some duration. We ...
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phase difference detection
For application of syncing sampling clock phase to carrier phase of received signal where the received signal is sampled with 10 times the carrier phase and modulated with the PSK shown in the figure (...
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Loop Bandwidth for Carrier Demodulation loop
I am trying to implement a simple MATLAB model for the demodulators for phase modulated signals (PSK) used in communication systems.
For the detection of the phase modulated output (PM out in the ...
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646
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PLL for Phase Demodulation and Carrier Tracking
I've been playing around with using a PLL for phase demodulation and it's working pretty well. The PLL locks to the carrier and the error term is the demodulated message signal. However, depending on ...
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Blind Carrier Synchronization
From my reading, I see that there are two ways people usually do carrier synchronization:
Decision directed, where the transmitted symbols are unknown are the receiver, decisions are made, and then ...
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825
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Designing a PI filter for a Costas Loop
I am currently trying to implement a Costas Loop in order to demodulate a BPSK signal. Here is the reference block diagram I have been using to design the loop:Costas Loop Block Diagram
I originally ...
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830
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How to allign audio signals after DTW?
Hello I am not a domain expert in signal processing but I need to align two audio signals.
I have seen the following page
https://librosa.github.io/librosa_gallery/auto_examples/plot_music_sync
I ...
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NDA timing estimation for mutli-level QAM(RC pulse)
What non-data0aided techniques are used to estimate the timing for multi-level QAM? For single level QAM(so 4 QAM) you can use variance minimization or power maximization but I'm not sure these ...
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Synchronising audio in realtime without knowledge of original signal
Was doubting whether this is the right SE forum to ask my (elaborate) question, so don’t hesitate to let me know if it’s not. Also, if anyone knows of a better way to title the question, feel free to ...
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Initial Clock synchronization between multiple smart phones (android OS) connected over Wifi?
I want to synchronize the initial clock of multiple smartphone devices (Android-based) for real-time VoIP communication. Basically, a MANET has been formed and I want to synchronize the clocks up to <...
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Digital PLL loses lock every time mesage crosses zero
I think my digital PLL is almost ready, but I've encountered this problem and I don't know what might be causing it, so I'd appreciate if you could help.
I'm using the DPLL in a Costas loop. It seems ...
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How to synchronize audio and video streaming for not fixed FPS streaming?
It's a 3-stage process.
In the first stage, a video (with audio) is recorded at a fixed 25 FPS rate. In the second stage, it's demuxed in two different channels and the video is processed. In the ...
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Need some references on sound quality evaluation and syncing
I have to do a project where I'm receiving the same sound signal from different channels (with different offsets), but they may not be consistent all the time. At any given time, I should decide which ...
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Maximum cross-correlation coefficient value for time delay estimation
I am using cross-correlation for time delay estimation of two synchronized recordings ($x_1$ and $x_2$) of a fixed sound source from two different locations.
I understand that the delay is associated ...
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