# Questions tagged [signal-processing]

Numerical analysis of a digitized signal

291 questions
Filter by
Sorted by
Tagged with
754 views

### Peak detection in a ucontroller using FFT

A project I am working on currently is to create a heart beat sensor using a finger plethysmograph. It returns a signal to my ucontoller that only includes positive peaks. For example, the ideal ...
1k views

### Is there an intuitive interpretation of a negative variogram “nugget” value?

A variogram plots the variance of the difference between sample pairs on a field (any dimensionality) against spatial separation (the "lag") of those samples. The extrapolation from observed small-...
415 views

### On the use of the periodogram of a time series

I have a time series of hourly measurements for a duration of one year: time <- 1:(365*24)/24 set.seed(1) x <- rnorm(length(time)) The measurements are ...
317 views

### Evaluating the variation in the power of a known periodicity

Consider the following example: ...
22k views

### How can I align/synchronize two signals?

I'm doing some research but have come stuck at the analysis stage (should've paid more attention to my stats lectures). I've collected two simultaneous signals: flow rate integrated for volume and ...
1k views

### What are some common measures of variation in an interval?

Context: I'm working on an app that "listens" to breathing/snoring and "diagnoses" apnea by taking note of pauses between breaths. For the most part this works well, but it's (rather amazingly) ...
6k views

### How to simulate Signal-Noise Ratio?

I have a vector of simulated data: data = c(0.47, 0.45, 0.30, 1.15, 0.82, 0.38, 0.51, 1.36, 1.72, 0.36) I've been adding noise to this by generating random ...
793 views

### Method to find 'principal components' of EMG recordings of reflexes

I have a series of electromyographic (EMG) reflex recordings, of which I would like to find out the principal components. My thoughts are that there are multiple processes that added together result ...
13k views

### What is a good way to measure the “linearity” of a dataset?

I have an empirically gathered dataset which relates two variables. Over a small range the relationship appears linear, however over a larger range there is clearly some second order polynomial ...
724 views

### Techniques for incremental online learning of classifier on stream data

Which may be good techniques to face this abstract problem? You have a data stream of a continuous signal, as one from a physical sensor. That signal has real (discretized) values, no attribute; ...
902 views

### Pattern of mouse (or keybord) clicks and predicting computer user's activity

Based solely on the temporal pattern of mouse clicks (a list of click times $[t_1,t_2,t_3,\ldots]$), is it possible to predict the computer user's activity? For example out of: working vs spending ...
1k views

### Finding the instantaneous period of a signal (or calculating period degradation)

I have a signal, of varying amplitude, and after a certain point in time, I expect to see the period of this signal lengthen. I am looking for a way to measure the lengthening of this period. Is this ...
3k views

### Analysing periodicity in sparse time series

I am interested in looking for periodicities in a several day long recording of electrical activity. The traces present a very steady baseline over which, from time to time, some short events (300-500 ...
103 views

### I need a new and improved DFT

The traditional Discrete Fourier Transform (DFT) and its cousin, the FFT, produce bins that are spaced equally. In other words, you get something like the first 10 hertz in the first bin, 10.1 through ...
714 views

### Are MFCCs the optimal method of representing music to a retrieval system?

A signal processing technique, the Mel frequency Cepstrum, is often used to extract information from a musical piece for use in a machine learning task. This method gives a short-term power spectrum, ...
109 views

### Three-parts correlation or equivalent?

I'm wondering what's the usual way for detecting "three-parts" association between variables. I'm not even sure about the name, so I apologize for any misunderstandings beforehand. Here is what I want....
1k views

### Wavelet smoothing at different scales

I would like to perform wavelet smoothing at different scales in R. I got the idea from this figure (panel A) were they measure the density/intensity of a particular signal at different scales. Here ...
758 views

2k views

### What is the best way to compare fluctuations of two signals?

I have some data acquired by an acoustic sensor with 1 Hz sampling rate. Due to some inevitable issues, I have some noise in my signal, saying 10% pollution. I'm looking for a reliable method for ...
2k views

### Online method for detecting wave amplitude

I would like to measure the amplitude of waves in a noisy time-series on-line. I have a time-series that models a noisy wave function, that undergoes shifts in amplitude. Say, for example, something ...
487 views

### How to average quantized and truncated data?

So I have data that has been quantized by an analogue to digital converter. (continuous data has been turned into discrete data and the values range from 0 to the saturation value , which is 127 in ...
962 views

### Boundary effect in a wavelet multi resolution analysis

What are the methods to minimize the effect of boundaries in a wavelet decomposition? I use R and the package waveslim. I have found for instance the function ...
258 views

### Compression theory, practice, for time series with values in a space of distributions (say of a real random variable)

Example of problem: Part of our research team is working on providing operationally wind power forecast. Usually, since there are different time scalse that interest forecast user, a forecast is ...
275 views

### How would you filter this?

This image show a histogram (200 bins) of accumulated distances from a radar distance meter (very noisy). The peak around 7 meters is an object. At thought this looked kind of like a normal ...
638 views

### Generalization of the Signal-Noise ratio for non-Gaussian processes

The signal to noise ratio is simple, and is usually defined in the context of simple Gaussian local-level models. In the cause of non-gaussian signal or noise models, do people do things more ...
2k views

### Using autocorrelation to find commonly occurring signal fragments

I have a sensor which is capturing accelerometer data as a person walks. What I'm interested in extracting is each signal fragment when a step is taken. The Z-axis is what is used since only one axis ...
4k views

### Smoothing time series data

I am building an android application that records accelerometer data during sleep, so as to analyze sleep trends and optionally wake the user near a desired time during light sleep. I have already ...
11k views

### Application of wavelets to time-series-based anomaly detection algorithms

I've been beginning to work my way through Statistical Data Mining Tutorials by Andrew Moore (highly recommended for anyone else first venturing into this field). I started by reading this extremely ...
3k views

### What is the difference between functional data analysis and high dimensional data analysis

There are a lot of references in the statistic literature to "functional data" (i.e. data that are curves), and in parallel, to "high dimensional data" (i.e. when data are high dimensional vectors). ...