Questions tagged [synchronization]

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Understanding the (complex) GNU Radio implementation of Mueller & Muller

I have some questions about the M&M implementation of GNU Radio that uses complex samples. I started reading the implementation for real values: ...
Gabriel's user avatar
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Sliding Window correlation vs cosine of relative phase

I create two band limited signals having a specific time-varying covariance at each time point using cholesky decomposition. My aim for this experiment was to show a scenario where sliding window ...
Sir-Lord's user avatar
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Can PLL for OQPSK be used for carrier frequency recovery?

This is the phase detector of PLL of OQPSK modulation. Apparently, it introduces a self-noise labeled in red which can’t be offset. I simulate this algorithm in Matlab, it doesn’t perform as well as ...
Xiang Li's user avatar
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Symbol Sync blocks in GNU Radio seem to use PID (well, PI) for their clock sync feedback loops. Why not IIR/FIR?

E.g. the Symbol Sync block has a Loop Bandwidth, which (if I read the source right) ends up as a PI loop. I know what PID does mathematically, and what FIR and IIR ...
Thomas's user avatar
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The MSE after each synchronization block doesn't go consistently down at the output of each block

I have a synchronization chain that consists of Coarse frequency synchronization block Frame synchronization block Symbol time synchronization block Fine frequency synchronization block PLL phase ...
Math_Novice's user avatar
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1 answer
122 views

CFO limit for correct LTE Zadoff-Chu Synchronization

I am working with Zadoff-Chu sequences in a Python simulation of an LTE-like communication system and need to understand the effects of carrier frequency offset (CFO) on these sequences. Specifically, ...
Sonny Wandel's user avatar
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25 views

Synchronization blocks and the domain in which they operate

I'm studying the full synchronization chain, and it's not clear to me at which domain each block works on in terms of sample vs. symbol domain. I'm particularly confused between frame synchronization ...
Math_Novice's user avatar
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Probability of miss detection and probability of false alarm in frame synchronization

I'm working on frame synchronization, and I don't fully understand the probability of miss detection and probability of false alarm in evaluating the performance of the synchronization block. As far ...
Math_Novice's user avatar
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Need to write a simple code in matlab of training sequence or zadoff Chu sequence for my OFDM signal-synchronization

I have written a complete code, in matlab, for my ofdm signal for the transmitter and receiver. Now I want to transmit my ofdm signal via wireless channel using SDR. Now, I need to combine a simple ...
Walkürie's user avatar
1 vote
1 answer
26 views

Is there any specific order for the synchronization blocks at the receiver?

I am working on frequency, time and phase synchronization at the receiver, and although there is a consensus that coarse frequency synchronization is the first block in the chain, I am confused about ...
Math_Novice's user avatar
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2 answers
118 views

What is the name of this FFT technique for carrier recovery?

https://dsp.stackexchange.com/a/67221/69442 What is the name of this FFT-based technique whose code is given in the answer and whose link I added above? Can I find information about this in any paper?
caneng's user avatar
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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 ...
Hoon's user avatar
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4 votes
2 answers
2k views

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. ...
Math_Novice's user avatar
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1 answer
291 views

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 ...
Xiang Li's user avatar
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1 answer
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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 ...
Greendrake's user avatar
1 vote
1 answer
410 views

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 ...
RH6's user avatar
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1 answer
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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 ...
BigBrownBear00's user avatar
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2 answers
294 views

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?
P76107077杰凱力艾's user avatar
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1 answer
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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 --> ...
Moses Browne Mwakyanjala's user avatar
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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 ...
Sajjad's user avatar
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1 answer
303 views

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 ...
Thomas's user avatar
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1 answer
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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) ...
Tania Guillot's user avatar
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0 answers
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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
Raphael Ngenyi's user avatar
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0 answers
47 views

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, ...
CipherX's user avatar
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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 ...
Moses Browne Mwakyanjala's user avatar
3 votes
1 answer
1k views

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 ...
Amudsen's user avatar
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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 ...
Moses Browne Mwakyanjala's user avatar
0 votes
1 answer
259 views

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 ...
Moses Browne Mwakyanjala's user avatar
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0 answers
155 views

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 ...
Okan Erturk's user avatar
1 vote
1 answer
220 views

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 ...
Johannes Mittendorfer's user avatar
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3 answers
1k views

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 ...
EL_9's user avatar
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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 (...
Aragorn's user avatar
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4 votes
4 answers
1k views

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 ...
Ali's user avatar
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-1 votes
1 answer
391 views

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 ...
AD23's user avatar
  • 79
0 votes
1 answer
129 views

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-...
Qw3rtzuiop's user avatar
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0 answers
66 views

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 ...
user67081's user avatar
  • 723
3 votes
2 answers
188 views

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 ...
Moses Browne Mwakyanjala's user avatar
2 votes
1 answer
304 views

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 ...
user67081's user avatar
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4 votes
1 answer
79 views

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 ...
Tom Huntington's user avatar
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0 answers
393 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 ...
ronyk's user avatar
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0 answers
143 views

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)...
dcs's user avatar
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-1 votes
1 answer
209 views

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 ...
Engineer's user avatar
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1 vote
0 answers
33 views

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 ...
Khan's user avatar
  • 141
1 vote
2 answers
39 views

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 ...
RM1524's user avatar
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1 vote
3 answers
113 views

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 ...
fl0ta'''s user avatar
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2 votes
2 answers
5k views

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. ...
Yaaseen Mohamed's user avatar
0 votes
2 answers
313 views

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 ...
Sampath's user avatar
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2 votes
1 answer
390 views

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 (...
user49745's user avatar
0 votes
1 answer
265 views

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 ...
sarthak's user avatar
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1 vote
1 answer
774 views

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 ...
user67081's user avatar
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