# Questions tagged [signal]

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### Phase shift in Fourier transform

Suppose we have a signal x(t). If we Fourier transform the signal to the frequency domain we get a complex function (has js in it). Do the js mean a phase shift and what does phase shift in a Fourier ...
14 views

### Fourier analysis of delta function

I have this periodic function: $f(t) =\delta(t)+ \sum_{n=1}^{\infty }\delta (t-n)+\delta (t+n)$ and I need to find its harmonics by finding the coefficients for the Fourier series. But how is this ...
1 vote
36 views

72 views

### How significant is signal noise from a BNC connector?

I'm trying to build a double cross antenna that can be folded/taken apart based on the design of the picture and receive signals from weather satellites. The idea is to make each of the four dipoles ...
91 views

### Active noise cancelling headphones - How fast does a digital signal processor have to be to perfectly cancel out noise with an inverted signal?

How fast does a digital signal processor have to be to perfectly cancel out noise with an inverted signal? Is it possible for a digital signal processor react so fast?
1 vote
148 views

### How to add a Gaussian noise signal with zero-mean in a given data set?

I have a real-time velocity measurement data set in a excel (.xlsx) file. I want to add the Gaussian noise signal with zero mean in this real-time data to create three set of pseudo measurements. ...
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### Is it possible that room noises could end up on the recording when recording audio from an analogue source?

I have a VCR with a tape cartridge playing in it. The video output (SCART/RCA) goes from the back of the VCR into my Elgato video capturing device's RCA cables. The Elgato device is then connected via ...
46 views

### How can I find the Transfer Function in Z-domain?

This is my signal; $y[n]=x[n]+0.8x[n-0.2]$ When I take Z-transform I get; $Y[z]=X[z]+0.8z^\frac{-1}{5}X[z])$ Then I found the Transfer function as; $H[z]=\frac{Y[z]}{X[z]}$ $H[z]=1+0.8z^\frac{-1}{5}$ ...
75 views

### Are there offsets in these accelerometers signals?

How you can see in the picture below, there are 3 signals from 3 piezo accelerometers placed on a oscillating 3D structure. The structure should vibrate only along the z axis (blue track), but there ...
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1 vote
42 views

### Quickly stopping a phone from attaching to a network

I struggled for a while to find which group I might ask this question in. Figured engineering minds would be the best. Some time ago I discovered a good friend was in an abusive relationship. This ...
23 views

### Can cross correlation be used to see if filtering of a signal has changed it too much?

I am filtering a signal, and want to check if I am not over filtering it , I wanted to use cross correlation , but I am not sure if it is a good technique. usually I get something like the following ...
29 views

### Small wireless proximity device to alert me when my cat gets into my WiFi range

I have the following situation. My cat goes outside every day, the problem is I have no way of telling when he is back around the house unless I go outside myself. I need some small wireless device I ...
1 vote
24 views

### Meaning of SNR in Instrument Specifications

I am evaluating the specifications of an FTIR instrument (Bruker Vertex) and came across the following statements/items: Signal-to-Noise 5 sec sample, 5 sec reference: >10,000:1 (<4.34 x 10-5 ...
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1 vote
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### What are the meanings of the second argument to the convolution?

I was trying to understand the convolution better and its mathematical properties and interpretations in engineering (specially in the context of computer vision). Recall the convolution:  s(t) = (...
298 views

### What is a "window of length N" in a signal processing algorithm?

I am reading a scientific paper in which an algorithm for evaluating an electromyography signal is described and I just don't get the meaning of the word "window" in the following part of a sentence: (...
12k views

### Is it possible to "boost" a WiFi signal using an aluminum soda can?

I recently discovered that one of my roommates had attempted to boost the WiFi signal by cutting up a soda can and placing it near the router, like this: My roommate was probably following an ...
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