## Top new questions this week:

### Estimate changing time lag between signals

Suppose I have two timeseries \$x_1(t)\$ and \$x_2(t)\$, shown in the image that I drew below. They look almost identical in general form, except some features are shifted slightly in time from one series ...

signal-analysis cross-correlation random time-series

### Why is the last value of an RFFT always real?

I am using numpy to do FFTs of real-valued data. And I don't understand why the Nyquist frequency is always real (or has zero phase). So, say A = rfft(data) then A[-1] is always a real value, and not ...

fourier-transform
 answered by Peter K. 1 vote

### Why upsample before modulation?

We're doing a project in which we're sending an OFDM frame, modulated to some appropriate carrier, over a channel. Before modulating, we are instructed to upsample and low-pass it. Is there a good ...

modulation interpolation

### Why power and not amplitude?

I'm reading 'The Scientist and Engineer's Guide to Digital Signal Processing'. It says for a noisy signal, the important parameter is not the deviation from the mean, but the power represented by the ...

noise

### Beginner level : Help in learning EM algorithm with an estimation example using Gaussian source

The problem is blind estimation of a communication channel by jointly estimating its coefficient and the input source \$x\$. Let \${y(n)}\$ be the corrupted output of an FIR channel with \$\{v(n)\}\$ as an ...

self-study system-identification parameter-estimation

### reducing pepper noise

For an image with pepper noise, presuming it is desirable to reduce the pepper noise, which operations, in which sequence, would you apply? Find an image, add pepper noise, and demonstrate your ...

image-processing noise

### Kalman Filter initial Q values

I have a 6 state Kalman Filter (Unscented). When I use a diagonal matrix only for Q (i.e only the diagonal has covariances), I get a "smooth" plot of estimate against actual. If I use the entire Q ...

kalman-filters

## Greatest hits from previous weeks:

### How to mimic/copy/fake someone's voice?

Is there any existing application to sample someone's voice and use it to modulate any other voice or synthesize a text to resemble the original one? For example, this Text-to-Speech Demo by ...

modulation voice

### How can I plot Frequency vs magnitude of wavelet transform?

I am running morlet continuous wavelet transform. I have got wscalogram of signal and now I want to Plot freq-magnitude like the following picture., but I don't know how to do it: I've used ...

frequency-spectrum frequency wavelet

### Acoustic characteristics of thoracic diaphragm

I am looking for any kind of information about the acoustic characteristics of the thoracic diaphragm. In particular, I'm looking for characteristics which will allow to differentiate it from other ...

image-processing acoustics ultrasound

### Time-domain filtering to match a target time-varying frequency response

I would like to implement a filter in the time domain based on a desired frequency response that changes over time. The initial goal is a bandpass filter with a time-varying center frequency, where ...

filters filter-design digital-filters
 asked by Del F 1 vote

### How do we find the capacity of MIMO wideband point to point system?

This question is in the context of digital communication . In many text books (wireless communication), when people derive the capacity of point to point communication system (one transmit one ...

digital-communications