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133 votes
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Why do color TVs make black and white snow?

If the receiver does not detect the sub-carrier for the "colour burst" signal which is transmitted during the horizontal blanking period the receiver switches on the "colour-killer" circuit so the set ...
Transistor's user avatar
  • 10.8k
16 votes

Why do color TVs make black and white snow?

The short and academically correct answer: a random noise signal is random. The lack of organization precludes that there is no separate color carrier present, and the set goes, as is already answered,...
Mike's user avatar
  • 161
8 votes
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How were the tones for DTMF chosen?

From: Engineers Garage Dual Tone Multi-Frequency: $f_1$ = 697Hz, 770Hz, 852Hz, 941Hz. $f_2$ = 1209Hz, 1336Hz, 1477Hz, 1633Hz. A key press on a DTMF keypad means a combination of $f_1$ and $f_2$ (...
StainlessSteelRat's user avatar
4 votes
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What should be the sample frequency to test the response of a filter?

2 times is the minimal sampling rate to ensure the signal can be possibly measured. This is called the Nyquist frequency. It shows that if your sampling rate is twice the frequency of the signal, you ...
Petrus1904's user avatar
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3 votes
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Shouldn't linear time-invariant systems be called affine time-invariant systems instead?

A system is some kind of function that maps an input as a function of t to an output. $$y(t) = H(u(t))$$ This system is linear if the following holds: $$y_1 = H(u_1), \quad y_2 = H(u_2)$$ $$\alpha y_1 ...
Petrus1904's user avatar
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3 votes
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Arduino DAC to Speaker

Your understanding of the issues is good. Q1: It's not overkill at all. All of the elements you've mentioned are needed. Q2: The low-pass filter frequency needs to significantly attenuate all ...
Graham Stevenson's user avatar
3 votes

Difference between Hysteresis, low pass filter and deadband in control theory?

No, or at least not as they are generally used and understood. Hysteresis is a nonlinear phenomenon where a variable trending in one direction tends to "pull" another variable along with it, and that ...
TimWescott's user avatar
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3 votes
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Problem with RHP zero in transfer function

This is because for all three of of your choices for the gain the closed loop system is unstable. Namely, for just an integrator as controller the gain should be below 1.5 in order for the closed loop ...
fibonatic's user avatar
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3 votes
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Converting time constant to bandwidth of 1st order system

Unit of frequency is not really $1/\mathrm{second}$. $$ 1\mathrm{Hz} = 1 \frac{\mathrm{cycle}}{\mathrm{second}}=360\frac{\mathrm{degrees}}{\mathrm{second}}=2\pi\frac{\mathrm{radians}}{\mathrm{second}} ...
AJN's user avatar
  • 1,109
2 votes
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PED or DSP for mechatronic student

DSP is relevant to any engineering field that involves gathering data and/or controlling something. That includes almost all robotics applications. It's not quite clear just from the title what "...
alephzero's user avatar
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2 votes

What is a Butterworth filter?

This.... this is the content of most of a semester on digital signal processing. You said, "I found [a book on signal processing], but it is a book of 700 pages with plenty of math." Well, yes. ...
Chuck's user avatar
  • 3,565
2 votes

what is 1P frequency in rotor (wind turbine)?

The constant rotational speed is the first excitation frequency, mostly referred to as 1P. The second excitation frequency is the rotor blade passing frequency: NbP in which Nb is the number of rotor ...
anon's user avatar
  • 21
2 votes

How to get natural frequencies from accelerometer measurements?

It depends on what your data looks like. I recently got some accelerometer data that looked like this after running it through Python's Scipy fft function: The results are pretty straightforward- ...
ericksonla's user avatar
2 votes
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What happens when very bright coherent light and weaker incoherent background light passes through doubly cascaded diffraction gratings?

The original question was along the lines of: "what happens if light passes through cascaded gratings". Before that question can be answered, you have to understand what a single grating does. See the ...
Han-Kwang Nienhuys's user avatar
2 votes
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Is it possible to make a tunable coherent light filter with 1.8 nanometer bandwidth for visible light?

Since you mentioned "pilot," I'm going to guess you're looking for a way to block laser pointers from distracting airline pilots. It really should be sufficient to use the same thing used in ...
Carl Witthoft's user avatar
2 votes

Why do color TVs make black and white snow?

The question was well answered by "Transistor" on Mar 21 at 14:31. The only part missing was that the other colour tv systems of the past, known as PAL (Phase Alternate Line) and SECAM (Séquentiel ...
Krut00's user avatar
  • 21
2 votes
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Non-observable effect of low-pass filter on the Transfer function (of Vibration measured with Laser scanner)

This is more of a continuation of the comments. Maybe later with more information it will be converted to a proper answer. Low pass filter frequency response Low pass filters have a specific response ...
NMech's user avatar
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2 votes
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How do I study the frequency response of a physical system with Arduino?

The arduino does impose some limits. But a classical frequency identification is build from a few steps: As the other comments already suggest, the design of a suitable input. As mentioned, a ...
Petrus1904's user avatar
  • 1,069
2 votes

How do mobile phones produce signals?

Your cell phone contains an oscillator. This is a circuit which when fed direct current converts it into ultrahigh frequency sine waves, which are then modulated by an encoded version of the audio ...
niels nielsen's user avatar
2 votes

Understanding Block Diagrams in Control Setups

but what specifically does the second block in this diagram mean? A block diagram like the one in the question represents the relation between output of a system and its input. you can think of the ...
AJN's user avatar
  • 1,109
1 vote

What is the output of a signal in time domain that passed through a High Pass Filter with simple transfer function

What you need to do is use Laplace transform to $U(t)$ so you would get $\mathcal{L}(U(t))=U(s)$ for example, if you are rusty on Laplace transforms (or their inverse), you can use wolfram alpha ...
NMech's user avatar
  • 24.3k
1 vote

Why do color TVs make black and white snow?

I disagree. Every color TV I got (and I repaired a lot of them in the '70's and '80's) displayed colored snow when tuned to blank air. In fact this was a much touted "feature" mentioned in consumer ...
Brian N Park's user avatar
1 vote

Signal convolution: continuous signals

Convolution is comprised of three steps: Introduce a dummy variable $\tau$ and use it to represent our functions. Also, reflect a function ($x(\tau)$) about $x=0$ with our dummy variable: $x(-\tau)$. ...
smollma's user avatar
  • 299
1 vote
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Nyquist Stability Theorem and Clockwise/Counter Clockwise Encirclements

After looking through the book "Feedback control of Dynamic Systems", I should say the clockwise encirclements are as much mentioned as the counter clockwise encirclements. However, the ...
Petrus1904's user avatar
  • 1,069
1 vote

How do I calculate the delay of two signals from different sensors?

When you are working with non-real-time data you can resample the data to make it synchronous. A data point with less data than the desired frequency will by up-sampled, and a data point to more than ...
ericnutsch's user avatar
  • 8,151
1 vote

how to filter model-free observations (e.g. Kalman filter)

The Kalman-filter is an observer, predicting the next system state based on an initial value. That prediction needs to be made based on some kind of model. The closest solution that I can come up ...
OpticalResonator's user avatar
1 vote
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Operating a load cell below excitation voltage

The load cell you linked to has a line item on the specs that says "Output: 2 mV/V nominal". Let's just say that you picked the version with 100 lbf full scale output. What that means is this: if ...
Daniel K's user avatar
  • 2,646
1 vote

What is a Butterworth filter?

Use a filter as a noise gate. Your signal or data with it phase reversed will drive the filter the filter in turn drives a vca. The original signal is being passed through the filter proper. Then you ...
Chrs's user avatar
  • 11

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