Questions tagged [pll]
The pll tag has no usage guidance.
36
questions
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19 views
How to correct phase using arctangent as Phase Detector
I have a DPLL that's trying to lock to a DSB-SC input signal with a carrier whose phase is $\theta$. So after some mixing and filtering (Costas Loop), I have these two signals ($\hat{\theta}$ is the ...
2
votes
0answers
52 views
Problem with 1st order PLL update equation
The output of a communication channel is given by:
$x(t) = \sum_n{a_n}h(t-nT)$,
where $\{a_n\}$ are BPSK symbols, $h(t)$ is the channel response, and $T$ is the symbol period. If there is an ...
3
votes
1answer
86 views
NCO loses lock after a while for certain values of alpha
EDIT: So the transfer function for my system is
$$ F_{nco}(z)=\beta E(z)/(z-1)$$
$$ z\Theta_{nco} (z)=\Theta_{nco} (z)+\alpha E(z)+\beta E(z)/(z-1)$$
So I would like to obtain $\Theta_{nco} (z) / \...
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13 views
Worst-case error bounds for PLL
I am working on a project that involves time synchronization and we want to derive worst case bounds for the accuracy of the current time given measurements with known error as input. Unfortunately ...
0
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0answers
46 views
Doppler shift in police radar
I don't understand how the radar frequency can be extracted from this diagram :
(source:https://copradar.com/rdrparts/)
and specially i don't understand what is the role of PLL and IF circuits and ...
3
votes
1answer
102 views
SRF-PLL discretization problem
So I've been working on how to digitally implement a static reference frame PLL (SRF-PLL), which is a quite popular PLL used for extracting three-phase grid angle.
This PLL works by using the DQ0 ...
0
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0answers
21 views
The mean value of phase noise as a stochastic process
What is the mean value of phase noise as a stochastic process?
Where can I get a theoretical analysis of this topic?
PS: PLL produces cos(2*πfct+φ(t)). The phase noise refers to φ(t). The mean value ...
0
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0answers
36 views
PLL carrier recovery: intermediate versus baseband
When looking at carrier recovery, a PLL is often applied to correct the frequency offset between the local oscillator and the transmitter after down conversion.
I'm wondering what happens to the PLL ...
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19 views
Resources on software PLLs in high latency systems?
For my master thesis I am prototyping a software PLL in Matlab using an Analog Devices AD9467 (ADC) evaluation+capture board. The VCO I am trying to control has an output frequency of approx. 2.2GHz ...
1
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0answers
109 views
How does a Costas Loop lock to one of multiple BPSK signals
I've been looking into how GPS receivers work in terms of signal processing. When a GPS receiver tracks the received signal, it often uses a Costas loop to synchronize the carrier.
How that works ...
1
vote
1answer
364 views
Residual carrier tracking with PLL
Residual carrier systems such as PCM/PM/NRZ and PCM/PM/Bi-phase are common in space applications. Compared to suppressed-carrier systems such as BPSK, the literature sources on residual-carrier ...
3
votes
1answer
275 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 ...
1
vote
1answer
69 views
upconverting a kHz/MHz signal to GHz
I want to know how in practice we can take a kHz/MHz signal to a GHz band?
Suppose we have an FSK modulated signal at around 300 kHz (or 20 MHz). I want to take it to 3.5 GHz, so about 3499700 kHz ...
1
vote
1answer
147 views
Basic PLL theory: voltage-controlled oscillator confusion
I am trying to write my first PLL in Python, and I've been making use of this excellent tutorial:
http://www.pythonpowerelectronics.com/contents/tutorials/tutorial1/pll_tutorial.pdf
Reading through ...
2
votes
0answers
183 views
Dynamic loop bandwidth for a Costas loop
I'm using a Costas loop for carrier recovery. The BER vs SNR (from GNU Radio Simulation) curve for different loop bandwidths (0.03,0.05 and 0.07) is shown in the graph below. It can be seen that the ...
1
vote
2answers
283 views
Software PLL tracking of carrier frequency in bandlimited transmission
My understanding is that a PLL(either in hardware or software) can recover the carrier frequency(or be used to correct the frequency offset) of a system. My question is how does this work when the ...
2
votes
1answer
489 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 ...
2
votes
0answers
551 views
Carrier recovery with the Costas loop : PLL pull-in range
I have created a channel model in GNU Radio (a modified version of the default GNU Radio Channel Block). Its performance under AWGN (without timing, phase or frequency offsets) aligns properly with ...
2
votes
1answer
755 views
PLL phase and frequency characteristics
I'm currently working with BPSK carrier phase and frequency recovery in GNU Radio. I have been able to use Costas loop and Frequency locked loop (four carrier acquisition) which are based on the ...
1
vote
2answers
200 views
Phase ambiguity in QAM modulation
I'm currently studying a decision directed carrier recovery scheme. Basically a PLL try to estimate the phase error in the current received symbol, the phase detector compensate the incoming symbol's ...
0
votes
1answer
211 views
Is Phase Locked Loop is essential for BPSK signal reception?
I'm noob in DSP studying BPSK communication between speaker and microphone using acoustic signal. I read article of this BPSK communication which says it needs Phase Locked Loop(PLL) sequence to match ...
2
votes
1answer
220 views
Transfer function of a PLL Loop Filter that can support a linearly increasing (chirping) frequency
What is a transfer function for a the loop filter of a PLL that can track a sinusoid of the form:
\begin{equation}
x(t)=\cos\left(2\pi\left(\frac{1}{2}c_0t^2 + f_0t + \phi_0\right)\right)
\end{...
1
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0answers
209 views
Unable to stabilize 8-PSK signal with self designed costas loop
I am trying to make a signal processing block which implements the costas loop to stabilize an 8-PSK signal. Here is the flowgraph with "costas_loop" being my block.
My workflow is the following -
<...
1
vote
1answer
3k views
How to correct the phase offset for QPSK I-Q data
I have an I-Q data of QPSK modulation, the data is is smeared and I have to correct the phase offset that causes the smearing problem, how can I apply the Phased-locked loop or the Costas loop on this ...
3
votes
0answers
326 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
...
1
vote
2answers
1k views
How to remove 50 Hz frequency noise from a PCM file?
Are you kind to tell me the odds or the means by which should I grab a clean signal with the $~50 \mathrm{Hz}$ hum removed using just programming?
I managed to make a program in Visual-C that ...
2
votes
0answers
248 views
Amplitude/phase recovery on noisy signal
I have a noisy signal that has an ac component of fixed frequency but variable amplitude and phase. I'd like to recover the ac component.
The signal (blue trace) is mostly smooth, but has a few ...
0
votes
0answers
97 views
phase locked loop
I have seen that to get the phase angle of a signal, we have to use PLLs. this PLL is modeling in order to get the phase angle about one frequency, which is the free running frequency of the VCO.
If ...
0
votes
2answers
254 views
FM demodulation amplifier with saturation
I'm trying to understand how FM demodulation works. I read a lot on the internet and as far as I understand, the main process is to extract the phase difference (that is also the output) between a ...
1
vote
3answers
1k views
PLL and zero crossing detection
Is there an algorithm which can give the frequency and phase of a three phase signal (three phase voltages) without using zero crossing detection.
I mean an algorithm which is done in open loop.
1
vote
1answer
189 views
Software implemented PLLs for signal synchronization, why use them?
In short I'm recreating a program that reads 3 sinusoidal signals through an ADC performs some manipulations and then reproduces these signals through a DAC. In order to reproduce these signals I need ...
2
votes
1answer
237 views
Why do most digital pll's only use the positive zero crossing?
I've been trying to get my head around digital plls from knowing nothing and seen that most examples only use the positive zero crossing, not the negative. I've tried to find the answer but the best i ...
2
votes
2answers
1k views
High modulation index PSK - carrier recovery
How to recover the carrier of a PSK signal that has high modulation index (eg. 750 symbols per second at carrier frequency 1500 Hz)? I guess that a PLL will not be able to lock onto it with such ...
2
votes
0answers
475 views
Doppler shift using PLL
I am trying to apply phase lock loop to calculate phase shift due to doppler effect and finally calculate the doppler frequency($\Delta f$). I am assuming that the received wave is of the form,
$r(t) =...
1
vote
2answers
268 views
Melodic or tonal pitch contour tracking?
What algorithms or methods can be used for the tracking of audio pitch contours? (Such as in musical vibrato and glissando, or for tonal vowels in languages such as Chinese?). Will a PLL work even ...
5
votes
1answer
743 views
Phase Locked Loop Basics
I am trying to better understand discrete-time PLLs. I drew a picture of a simple feedback system here:
I want to be able to describe and understand the system at v(t) and y(t). I found a fairly good ...
