Questions tagged [synchronization]

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3answers
46 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 ...
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2answers
88 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. ...
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2answers
37 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 ...
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1answer
64 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 (...
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1answer
45 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 ...
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1answer
68 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 ...
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3answers
95 views

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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0answers
75 views

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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1answer
38 views

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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0answers
35 views

(Frequency Offset): Relationship between Normalized Carrier Frequency Offset (normalized CFO) & ppm in OFDM system

How can I change a normalized carrier frequency offset (CFO) to ppm? And If the DAC sampling rate is 30GS/s, and the clock frequency is 15GHz, then should I use 30G or 15G when I calculate ppm? ...
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1answer
67 views

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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1answer
34 views

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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1answer
20 views

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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2answers
76 views

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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1answer
41 views

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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1answer
34 views

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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0answers
93 views

Implementing Costas loop for 4-PAM

EDIT 2: OK, regarding the code I’ve pasted below, and seeing the FFT plot, I suspect the LPFilters aren’t working since I’m getting $0.5*m(t)*[cos(2 \pi f_c t ( \theta_e)+cos(\theta_e)]$ instead of $0....
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1answer
270 views

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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0answers
225 views

How is DJI OcuSync wireless link physical layer implemented?

I'm looking for documentation on the wireless command link of the DJI OcuSync. I found this website (in Chinese). It seems like an OFDM link that uses Alamouti codes? I'm specifically interested in ...
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1answer
46 views

Synchronization Accuracy Required For Communications

One of the biggest problems in phase modulated communication is discovering when your signal has arrived. High accuracy in this area is important, as even a quarter wavelength error can cause the ...
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1answer
76 views

QPSK demodulation problem due to apparent transmitter clock frequency drift

I am using FPGA to generate 10Mbaud QPSK signal in two channels corresponding to two quadratures. Upsampling to 1GSample/s (using raised cos filter for interpolation) and complex upconversion (f_up=...
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1answer
422 views

GNU Radio loop bandwidth normalization

From GNU Radio documentation, the control_loop block proposes loop bandwidth values in the range $[\frac{2\pi}{200}, \frac{2\pi}{100}]$ in radians per sample. Some blocks, like the new timing symbol ...
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1answer
118 views

Synchronize a software waveform generator

I'm having some trouble with a software waveform generator I'm attempting to put together. Especially with synchronizing the waveform. Goal Generate a mains synchronized (50 Hz) sinusoidal waveform ...
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1answer
171 views

Frequency Hopping Spread Spectrum Synchronization Methods

Frequency-hopping spread spectrum waveforms change the carrier frequency at some interval. I can see if the frequency is constant for the duration of an entire packet, the pilot symbols could be used ...
1
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1answer
260 views

OFDM: How to do the carrier recovery of the quadrature(I/Q) demodulation

For an OFDM system, after the OFDM modulation, the quadrature modulation is used to move the signal from the baseband to the pass-band. But when it comes to the receivers, I can't find any way to make ...
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0answers
126 views

Band-edge filtering for an RRC pulse-shaped manchester/biphase-encoded bitstream

Band-edge (derivative matched) filters can be used to generate an error signal for frequency locked loops (real part) or symbol timing loops (imaginary part). The derivation of the band-edge filters ...
2
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1answer
683 views

Timing recovery in GNU Radio : Variable rate vs Fixed rate operation

I have been wondering about the implementation of timing recovery blocks in gnuradio. In literature, for asynchronous sampling, all that is needed are error detector (MM, ML, Gardner etc), a loop ...
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2answers
954 views

Trouble with time-syncing two radio signals using cross-correlation

I posted a similar question a while ago here (I'm posting this follow-up since I'd like to focus more on cross-correlation now). I have a setup where I have two software-defined radios connected to ...
3
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0answers
147 views

Synchronization of BPSK with variable-length symbols (ISO 14443)

Does anyone have an idea how one would perform BPSK symbol synchronization if symbol length is allowed to vary? As dumb as that sounds, this is not a theretical question.The "Proximity" Type B NFC ...
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2answers
70 views

Synchronization with a specified sequence

I'm currently creating a project in Matlab where I'm simulating a communication, based on the SSB modulation, between a transmitter and a receiver. I've added a Barker sequence in the trasmitted ...
2
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2answers
359 views

How can I synchronize signal from an LED and TTL pulses better?

I would like to synchronize my video and voltage data using Python. (I obtain these data using Bonsai and Open Ephys for an open field exploration experiment.) I sent $150\text{ ms}$ long TTL pulses ...
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0answers
30 views

How does the M-law Synchronizer work?

Relatively new to DSP, I've came across the approach for phase-estimation of PSK-Signals x(k): My question is: What do we get by exponentiating the Baseband-Signal?
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1answer
462 views

FFT based symbol synchronization for digital demodulation

Where can I read more about "slow search" methods for symbol synchronization based on FFT for extracting a clock signal from the modulated signal? I have read here (8.7 Symbol synchronization) One ...
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0answers
230 views

Frequency Domain Variant of Pearson's Sample Correlation Coefficient?

Suppose that you need to find (i.e. acquire) $x_1$, a short data packet with a known bit sequence preamble (i.e. a PRBS BPSK), in $x_2$, quantized samples recorded from the output of an ADC. You don'...
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1answer
218 views

OFDM synchronization using training symbols

In OFDM receivers, special OFDM training symbols for which the data content is known, can be used to perform the synchronization process. A correlation operation is performed between the received ...
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0answers
68 views

Detection over AWGN analysis disagrees with Monte Carlo simulation

I have a fixed vector $\mathbf{s} \in \{\pm1\}^m$ and a random vector $\mathbf{d} \in \{\pm1\}^m$. I send either $\mathbf{x} = \mathbf{x_1} = [\mathbf{s}\space\mathbf{d}]$ or $\mathbf{x} = \mathbf{...
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1answer
321 views

Synchronizing 2 seperate speech audio signals

I have two speech signals: one with a man reading a passage, and one with a woman reading the same passage. I want to synchronize these signals so that, for each word, their readings line up. The ...
2
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0answers
269 views

Software based synchronizing of multiple data streams/sensors with slightly differing sampling rates

Situation: I try to synchronize the data streams of multiple sensors (ADXL372) of the same type but with different data output rates. The data sheet states all sensors should have the same sampling ...
0
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1answer
694 views

Measure the amount of drift in video and audio frames

I setup a stereo system using 2 GoPro Hero Session Cameras, since I need a larger baseline than the one of the Dual Hero System. This unfortunately means the two cameras are not ...
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0answers
723 views

Synchronizing signals with different sample rates

I am relatively new to signal processing, so I am still missing some basic knowledge, but I am trying to improve as much as I can. I am trying to synchronize two signals with matlab using cross-...
2
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1answer
445 views

Band edge filter for raised cosine impulse

I'm hoping to use an implementation of a frequency-locked loop for rough frequency synchronization in a PSK31 demodulator. The approach is to define a filter that is the derivative of the matched ...
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1answer
1k views

Acceptable Carrier Frequency Offset for Specific BPSK system

I've been working to build a transceiver system, with details as follow: Consists of Lime LMS6002D MyriadRF-1 board (RF front-end) and own-designed multi-proc SoC (baseband processor). SoC is running ...
1
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1answer
113 views

Is Spectral Coherence (MSC) dependent to the initial amplitude of the comparing signals?

Given the signals \begin{align} x(t) &= A_1\sin(\omega t)\\ y(t) &= A_2\sin(\omega t) \end{align} Do $A_1$ and $A_2$ play a role in the $C_{xy}$ coherence estimator? MATLAB's ...
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3answers
262 views

Sampling and Reconstructing Digital Signal

Say that I have a digital signal (a bitstream actually) whose output changes every 100 mS. I don't know exactly when it changes relative to my sampling, only that that the next bit to capture appears ...
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0answers
459 views

How can I perform timing recovery from the envelope of PSK signals?

I'm trying to reimplement FDMDV in GNU Radio, largely for educational purposes. It consists of 15 PSK subcarriers, 75 Hz apart, 50 symbols/sec each. The center one is BPSK and alternates phase each ...
3
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1answer
221 views

Why does signaling overhead for time synchronization scale up with the number of transmitter nodes in a multiple access system?

I was recently reading about random multiple access methods without time synchronisation (of the pure Aloha type). In this paper it is stated that, The need for transmitter synchronization is a ...
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1answer
267 views

How to find a know signal in another signal which contains other signals along with the signal i need in python

I am working on BPSK with sound waves a carrier waves. Actually I am modulating my data with some known sync bits along with the information I need to send. So the things I will be having at ...
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1answer
104 views

How to find the time instant where my sent signal and received signal can synchronize?

I am having two .wav files, one is modulated wave that is made into a .wav file and another is a recieved .wav file which is recorded from microphone while playing first modulated .wav file. So now ...
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0answers
360 views

Symbol timing recovery design

I am trying to design the Symbol timing recovery(#STR) block of #DVBS Receiver. These are the specifications Symbol rate ($f_s$) = $2\textrm{ MHz}$ Acquisition range = $10\%$ of Symbol rate ...
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1answer
884 views

Loop bandwidth for symbol timing recovery

I am trying to design the Symbol timing recovery (STR) block of DVBS Receiver. How should I chose the loop bandwidth and damping ratio for determining the loop filter coefficients $k_1$ and $k_2$? ...