Engineering Stack Exchange
Engineering Stack Exchange

Questions tagged [signal]

37 questions
16
votes
3 answers

Can wifi signal reception be improved by opening a door?

A wifi user is in a different room than the router. The computer is having a hard time connecting and receiving the wifi signal. Can the wifi signal from the router to the computer be improved by opening a door to the room where the computer is?
Mowzer
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10
votes
1 answer

Response of a system to a step function (Heaviside function)

I'd like to compute the response to a step function of a electrical/thermal system. Generally I can "easily" compute the transfer function $H$: $$H(\omega) = \frac{V_{out}(\omega)}{V_{in}(\omega)}$$ Since the Fourier transform ($\mathcal{F}$) of the…
Worldsheep
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10
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4 answers

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 internet guide like this one, which advises shaping the…
hangar
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8
votes
1 answer

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: $$ s(t) = (x * w)(t) = \int x(a) w(t-a) da$$ the first…
Charlie Parker
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8
votes
1 answer

Best way to send a signal in a very low frequency (250Hz)?

I am a programmer facing an electronic question, so I thought here is the place to ask! I have a magnetic field sensor which provides me with magnetic field values (XYZ axis) 250 times a second. An electronic circuit with a programmable…
rubmz
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7
votes
0 answers

BER peroformance of MPSK and MQAM in Rayleigh fading channel

I have a question regarding bit error rate (BER) performance over the Rayleigh channel. I observed BER performance over the AWGN channel using Simulink in MATLAB. I used to change the "SNR" parameter in the AWGN block to get the BER. What if I want…
Sara
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4
votes
2 answers

Finding the sampling period to avoid loss of signal

We have: $$ s(t) = 4u(t)−u(t−1)−2u(t−2)−2u(t−3.5)+2u(t−4) $$ where $u$ is the Heaviside function. I had to draw the graph and find the minimum sampling period so we wont have loss of signal. I have drawn the graph. $t=kT$ where $T$ is the sampling…
sdfdsffsdf
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4
votes
2 answers

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: (First full paragraph of page 4) "Fig. 5 shows…
zerogravity
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4
votes
0 answers

Implications of concatenating EEG signals

I am wondering about the mathematical implications of concatenating very small windows from different trials. All of the trials are the same size, and are for the same period of time after a stimuli. In other words, let's say my data has 3…
tTimoteof
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3
votes
1 answer

signal-to-interference-plus-noise ratio (SINR) and others calculation

I am considering some empirical signal propagation models (like Hata, Ericsson models) to calculate 4 parameters: Path loss Received Signal Strength (RSS) signal-to-interference-plus-noise ratio Throughput Path loss is okay as each propagation…
Tana
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2
votes
1 answer

Hilbert transform LTI

I'm studying the Hilbert transform and its properties. I found out that Hilbert transform can be considered as a linear time-invariant system. How can I show this? I guess this should be trivial as my book does not show it.
Mazzola
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2
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0 answers

When working with generic electrically shielded signal cable, can I treat the unshielded strands of wire as signal reference ground?

I am working on a CNC application where one controller board will be sending signals to another board. The environment may have electromagnetic interference (EMI) from nearby motor activity, so these relatively low voltage (3-10V) signals may…
user391339
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2
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1 answer

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?
water castle
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2
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1 answer

What kind of signal is the signum function? A power signal or an energy signal?

I'm studying "signals and systems". We can indentify two kinds of signals: power signal and energy signal. The definitions are: Energy of a time-continous signal $$ E_x = \int_{-\infty}^{+\infty}{|x(t)|}^2dt $$ Power of a time-continous signal $$…
GenKs
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2
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0 answers

How do mobile phones switch 4G/3G/2G?

I would like to know the algorithm of switching between 4g/3g/2g. When will the phone switch from 4G to 3G or from 3G to 2G, when we select for corresponding option in the mobile phone. Is it based on dBm/RSCP etc? I am looking for some technical…
sudheesh
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