131 votes
Accepted

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 ...
  • 8,794
15 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,...
  • 151
7 votes
Accepted

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 $f_2$ (...
5 votes

How can I filter out a signal while extracting only the desired one?

First, I would recommend that you create a frequency spectrum of your signal. From your question I interpret that you already know the frequency of your sinusoidal signal. A common way for the ...
  • 215
5 votes

How can I filter out a signal while extracting only the desired one?

It sounds like what you're looking for is a bandpass filter. It will filter out any signal outside of a given frequency range. If the noise isn't too strong, the main signal should come through fairly ...
4 votes

Does a Faraday cage effectively act as a notch filter?

First, here's a great answer to a similar question on the physics.SE. I will attempt to summarize it a bit and tune it to your question, but I think that all of your answers are already in that thread ...
  • 394
4 votes

Finding the sampling period to avoid loss of signal

The smallest feature that you need to capture is the dip between 3.5 and 4. If you use a sampling period which is greater than 0.5, then you may end up not capturing this feature. The sampling ...
4 votes
Accepted

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 ...
  • 1,079
3 votes
Accepted

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 ...
  • 1,603
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 ...
  • 2,263
3 votes
Accepted

Are there any methods to work out what appliances are running in my home from an aggregate power consumption sampled 6 times a minute?

The word that will unlock your searching is disaggregation - there's quite a lot of research going on right now into energy disaggregation. These generally involve some kind of learning algorithm, ...
  • 3,701
3 votes
Accepted

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 ...
3 votes
Accepted

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 ...
  • 1,079
2 votes

Acoustical Design considerations for Active Noise Cancellation Project for Air vent

The first big problem is with your speaker placement; the 'anti-noise' speaker should be as close to the 'noise' speaker as possible. Another big problem is with the speakers you are using; they are ...
2 votes

Acoustical Design considerations for Active Noise Cancellation Project for Air vent

I don't think there's enough room in a comment to add all of this, so that's why I'm posting this as an answer. What do you mean when you say, "I have implemented LMS on Labview"? What is LMS? What ...
  • 3,535
2 votes

Does a Faraday cage effectively act as a notch filter?

I would say a Faraday cage (at it's simplest) is more like a high pass filter. And more specifically one that blocks only Electric fields. The metal box we put our electronics in is a Faraday shield. ...
2 votes

How can I filter out a signal while extracting only the desired one?

(How do you know the signal frequency?) OK this may be over the top for your application, but if you have access to the drive (reference) signal, then you can make a lock-in or synchronous detector.
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- ...
2 votes
Accepted

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 ...
2 votes
Accepted

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 ...
2 votes

Finding the sampling period to avoid loss of signal

To prevent loss of signal you need to sample at twice the highest frequency presented in the signal. This is also known as Nyquist rate. Assuming that time t is in seconds, the smallest time period ...
2 votes
Accepted

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 "...
  • 12.5k
2 votes

What is a Butterworth filter?

A Butterworth filter is just a type of filter (there are lots of types) with a particular shape to its response. In your situation, a Butterworth filter would be used as a low-pass filter (LPF) to cut ...
  • 21
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. ...
  • 3,535
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 ...
  • 21
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 ...
  • 21
2 votes
Accepted

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 ...
  • 22.9k
2 votes
Accepted

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 ...
  • 1,079
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 ...
1 vote

Fourier serie signal approximation

If you already know the explicit form of the function $f(x)$, then it's possible to find the periode by solving this equation $f(x) = f(x+P)$. If you have a graphical representation of the function (...

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