133
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 ...
- 10.9k
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,...
- 161
8
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 $f_2$ (...
- 2,477
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 ...
- 1,099
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:
$$y_1 = H(u_1), \quad y_2 = H(u_2)$$
$$\alpha y_1 ...
- 1,099
3
votes
Accepted
Arduino DAC to Speaker
Your understanding of the issues is good.
Q1: It's not overkill at all. All of the elements you've mentioned are needed.
Q2: The low-pass filter frequency needs to significantly attenuate all ...
- 156
3
votes
Difference between Hysteresis, low pass filter and deadband in control theory?
No, or at least not as they are generally used and understood.
Hysteresis is a nonlinear phenomenon where a variable trending in one direction tends to "pull" another variable along with it, and that ...
- 2,692
3
votes
Accepted
Problem with RHP zero in transfer function
This is because for all three of of your choices for the gain the closed loop system is unstable. Namely, for just an integrator as controller the gain should be below 1.5 in order for the closed loop ...
- 1,663
3
votes
Accepted
Converting time constant to bandwidth of 1st order system
Unit of frequency is not really $1/\mathrm{second}$.
$$
1\mathrm{Hz} = 1 \frac{\mathrm{cycle}}{\mathrm{second}}=360\frac{\mathrm{degrees}}{\mathrm{second}}=2\pi\frac{\mathrm{radians}}{\mathrm{second}}
...
- 1,177
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?
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. ...
- 3,565
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 ...
- 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- ...
- 762
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 ...
- 24.2k
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 ...
- 1,099
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 ...
- 15.1k
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 ...
- 1,177
1
vote
Adaptive downsampling of time-series data?
A technique I've seen used for air conditioning units, is that you can create a new log when a) the temperature stops being constant or b) changes in slope.
In essence, if for a long time you have ...
- 24.2k
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
...
- 24.2k
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 ...
- 11
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: $x(-\tau)$.
...
- 299
1
vote
Accepted
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 ...
- 1,099
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 ...
- 8,226
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 ...
- 1,923
1
vote
Accepted
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 ...
- 2,656
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 ...
- 11
1
vote
what is 1P frequency in rotor (wind turbine)?
In wind turbine, is the number of revolution taken in 1 s is called 1P frequency?
According to Dynamics of offshore wind turbines
supported on two foundations you are correct.
If not, is it ...
- 10.9k
Only top scored, non community-wiki answers of a minimum length are eligible