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# Tag Info

## Hot answers tagged analytic-signal

Accepted

### Is there a relation between an analytic signal (signal processing) and an analytic function (complex analysis)?

There is a relationship between these two concepts. Let the complex function $f(z)$ be analytic on and inside a simple closed curve $C$ in the complex plane. Then Cauchy's integral formula states that ...
• 90.4k
Accepted

### Does analytic signal have positive instantaneous frequency?

It is not the case that the instantaneous frequency of an analytic signal is always positive. In general, the instantaneous frequency can become negative, also for analytic signals. I'll show this ...
• 90.4k

### How to "draw" the function/wave to send symbols using QAM?

The baseband QAM signal is complex, and the only way to draw it is by doing two drawings, one for the in-phase (real) component, and one for the quadrature (imaginary) component. The passband QAM ...
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• 90.4k

### Envelope detection in MATLAB

The Hilbert is very simple to implement with high accuracy for narrow band signals such as the OP presents (we just need to introduce a perfect quadrature phase shift and maintain the amplitude ...
• 52.1k

### Calculate and interpret the instantaneous frequency

Sorry to provide an answer a year after the fact, but I stumbled across this post while searching for articles on this very topic. Your questions reflect the widespread disagreements and ...
• 31
Accepted

### Phase change rate of human speech

I will not address the question whether or not it is meaningful to compute the instantaneous frequency of a speech signal. Instead I will show you a better method for computing the instantaneous ...
• 90.4k
Accepted

### Separate Simple Signal into Exponential Components

Your problem seems to be finding the analytic signal to a given real signal. What you apparently need is the Hilbert transform. This will allow you to "recreate" the imaginary part of $y(t)$ from the ...
• 431

### Definition of minimum-phase system

one thing about a non-minimum phase system (with a rational transfer function), is that it can be thought of as the series concatenation (or cascade) of a minimum-phase system, having identical ...

### QAM Constellation Construction - Basic 4/8 QAM

One can choose any mapping desired from the unique data sequences to the symbol locations on the QAM constellation. It is common and usually best to Gray-code the mapping such that only one bit ...
• 52.1k
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### CODECS used for VoIP calls

Let me put in an unconnected form things about audio codecs. Audio can be music or speech (discluding ultrasound, sonar etc). Music is wideband and requires high-fidelity. Speech has a lower ...
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### Alternative to Hilbert Transform

If your signal is relatively narrow band (does not occupy the entire Nyquist bandwidth) then an FIR filter would be more efficient to compute the band-limited Hilbert Transform vs an FFT which ...
• 52.1k
1 vote

### Construct complex signal from a real-valued time series and Hilbert transform

Clearly, $A(t)$ is the analytic signal of $v(t)$. How so ? This is simply a conversion from cartesian to polar co-ordinates. Every complex signal can be written this way regardless of whether it's ...
• 45.4k
1 vote
Accepted

### Envelope detection in MATLAB

Is it because I am using a Hilbert filter of order 63 ? Yes. The Hilbert Transform is difficult to implement in practice. Its impulse response is infinitely long and infinitely non-causal. That means ...
• 45.4k
1 vote
Accepted

### Can a cosine modulated complex valued baseband signal be transmitted over physical channels?

There are two interpretations of this problem. One is that only real voltages and currents can exist in the real world. Complex signals exist to simplify calculations, and in the DSP realm, where ...
• 15.3k
1 vote

### How an algorithm for measuring the analytic signal (Hilbert transform) gives us complex value at the end?

In general for the FT, in order for the result for the DFT or IDFT to be real, the waveform MUST be real and even (symmetric about vertical axis) or imaginary and odd (anti-symmetric about the ...
• 52.1k
1 vote

### How an algorithm for measuring the analytic signal (Hilbert transform) gives us complex value at the end?

(while we expected it to be real). We certainly did not expect this to be real. Quite on the contrary: a real time domain signal has a spectrum that is conjugate symmetric. Be zeroing out the ...
• 45.4k
1 vote

### Magnitude of the analytic signal

Using your notation for the (complex valued) analytic signal; $$s(t) = x(t) + j \hat{x}(t) = |s(t)| e^{j \phi(t)} \tag{1}$$ where $x(t)$ is the message signal and $\hat{x}(t)$ is its continuous-time ...
• 28.3k
1 vote

### Determine the haar wavelet function is linear or nonlinear

Linearity can play at different levels in this context: The Haar wavelet functions are piece-wise affine (constant), not linear (but sometimes people call affine "linear"). Any standard ...
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Only top scored, non community-wiki answers of a minimum length are eligible