20
votes
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Is a notch filter for 50 Hz without delay possible?
You could use a 2nd order IIR notch filter as I describe in this post Transfer function of second order notch filter - That post demonstrates a 50 Hz IIR notch with 1 KHz sampling.
[Update: As @...
- 53.8k
10
votes
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Flat fading criterion of OFDM subcarrier spacing
Your mathematical derivation is correct, your $H[k]$ is the single-tap equalizer (i.e. one tap for each subcarrier, and the subcarriers do not mix with each other. That's the orthogonal in OFDM).
...
- 6,248
10
votes
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Delay a signal in time vs in frequency
Is there any trade-off in numerical precision or speed?
Yes. For delays that are integer multiples of the sampling period method 1 is far superior: it's computationally efficient, it's bit-exact, it'...
- 47k
8
votes
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Digital delay effect: avoiding clicks on delay time change
If you are not changing the delay length very often, and you don't want to have a Doppler effect that comes from continuously changing the delay length, then try a cross-fade. Both delay lengths ...
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8
votes
Is a notch filter for 50 Hz without delay possible?
This is an uncertainty principle kind of problem: there is no way to make a reliable filter with little delay that will suppress a narrow band around 50Hz since the narrowness of a criterion in ...
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7
votes
Accepted
How to calculate a delay (correlation peak) between two signals with a precision smaller than the sampling period?
This is basically what @hooman suggests: fit a parabola to the three points near the peak of the sample cross-correlation of the data.
Using the formula for $p$ from Julius O. Smith - Peak Detection:
$...
- 25.9k
6
votes
Is a notch filter for 50 Hz without delay possible?
I joined this community only to answer your question as I had a similar problem about 2 years ago, in ECG domain though.
What I've found (unfortunately I cannot trace the source back) is a very ...
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5
votes
How to calculate a delay (correlation peak) between two signals with a precision smaller than the sampling period?
Lagrange parabolic estimator
The standard Lagrange polynomial parabolic interpolation peak finding formula from Peter's answer,
$$p = \frac{1}{2} \frac{\alpha - \gamma}{\alpha - 2\beta + \gamma}$$
...
- 13.6k
5
votes
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Maximum cross-correlation coefficient value for time delay estimation
As your plot shows, the second form allows for the correlation peak to be negative. Now, what does a strong negative cross correlation mean? It means the signals are very similar, except one has a ...
- 2,463
5
votes
Is a notch filter for 50 Hz without delay possible?
I assume this a for real-time processing. Otherwise, you could simply discard the number of samples corresponding to the group delay.
1st solution - Use an IIR notch filter. You could use this ...
- 3,787
4
votes
Digital delay effect: avoiding clicks on delay time change
If you have a continuously varying delay like, for example, a chorus or flanger, you need a to implement a time varying fractional delay in addition to your regular (integer) delay line.
If you only ...
- 47k
4
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How to calculate a delay between two signals in frequency domain?
Calculating a delay between two signals is not as simple as you described and it cannot be generalized as easily either.
The case for two sinusoidal signals seems trivial, as the delay then ...
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4
votes
How to calculate a delay (correlation peak) between two signals with a precision smaller than the sampling period?
You can fit a curve to the points around the peak of the cross-correlation obtained by xcor and find the peak of the fitted curve. Ideally, you know the cross-correlation function of your signals and ...
- 321
4
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Digital delay effect: avoiding clicks on delay time change
The problem here is a discontinuity in the signal, which results in the click you're hearing. A possible solution is to make the delay variation as smooth as possible so that step-like discontinuities ...
- 43
4
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What exactly is a 90 degree phase shift of a digital signal in FM demodulation appraoches?
The OP asked about a phase shift specifically but from the written details without seeing the actual demodulator implementation, I suspect he may possibly be asking how to implement the delay that is ...
- 53.8k
4
votes
Delay in Savitzky-Golay filtering
Standard Savitzky-Golay filters are linear phase (type I) FIR filters. So they have an odd number of filter coefficients $2N+1$, and the delay equals $N$.
For a good overview of Savitzky-Golay ...
- 91.3k
4
votes
Is a notch filter for 50 Hz without delay possible?
For removing mains hum from EEG signals, you can take advantage of the fact that the noise is stable in phase and frequency, albeit not necessarily in amplitude depending on the overall electrical ...
- 141
4
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How to Reduce Phase Lag Caused by Kalman Filter
Have you considered trying a constant jerk model as opposed to a constant acceleration model? Perhaps a higher order model would capture the acceleration better. See, for instance:
K. Mehrotra and P. ...
- 41
4
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Accepted
How to Reduce Phase Lag Caused by Kalman Filter
What you're experiencing is the transient lag of the Kalman Filter.
The Kalman Filter, using the Measurement and Process Noise balances between begin very adaptive to being an aggressive smoother.
In ...
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4
votes
Delay a signal in time vs in frequency
At the risk of blowing my own trumpet and that of my co-author, Bob Williamson, there is also this paper which shows the equivalence of three techniques referred to in the FIR link in Ben's answer and ...
- 25.9k
4
votes
Accepted
Estimate the time delay of two signals
The issue is we are looking for likeness but the values are scaled beyond that metric. In the OP’s construct all symbols used should have equal weight toward the correlation determination; for example,...
- 53.8k
4
votes
Issue Understanding Time Delay of a Digital Filter
To help your intuition, consider a sinusoidal signal with frequency $\omega_0$ and some arbitrary but constant phase $\phi$:
$$x[n]=A\sin(\omega_0n+\phi)\tag{1}$$
Delaying the signal $x[n]$ by $n_0$ ...
- 91.3k
4
votes
How to reduce clicking in an audio signal with seek jumps?
Clicking noise on seek is a result of discontinuity in the audio signal. One way of reducing this noise is applying a fade-in effect for few frames post seek.
- 665
4
votes
Wideband phase vs time delay beamforming correction
I am studying a 1D beamforming for wide-band signals, so that applying only phase weights to each individual antenna would steer the beam for the central frequency. For other frequencies the steering ...
- 32k
3
votes
Accepted
Confused with filtering linear chirp signal using band-pass filter
You are seeing the difference between "wide band FM" and "narrow band FM" in your modulated waveform. Observe your modulation index for each case and then review the sideband levels versus mod index ...
- 53.8k
3
votes
Accepted
Regarding the advantages of generalized linear phase filters
Note that with the definition of generalized linear phase $\phi(\omega)$ according to
$$H(e^{j\omega})=|H(e^{j\omega})|e^{j\phi(\omega)}\tag{1}$$
and
$$\phi(\omega)=\alpha\omega+\beta\tag{2}$$
the ...
- 91.3k
3
votes
Interpreting the cross correlation results
Yes and no. In principle, you can use the peak of your correlation function. However, it is not at 10000. The correlation function is symmetric around 0, so your peak is actually much closer to zero ...
- 2,463
3
votes
Delay a signal in time vs in frequency
As Hilmar pointed out, for delays that are integer multiples of the sampling period, method 1 is far superior.
Also, Method 1 is more suitable for real-time operations as you don't need to buffer the ...
- 3,787
3
votes
Accepted
Audio compressor delay/lookahead
What is typical delay times for a compressors or limiters delay/lookahead time?
I don't think there is "typical": it depends a lot on the bandwidth, frequency content and what specifically ...
- 47k
3
votes
Audio compressor delay/lookahead
In another life, maybe about 25 years ago, I did a few simple compressors in DSP code and I did toss in a delay on the audio, which is equivalent to a lookahead on the audio envelope. The delay was ...
- 21.1k
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