# Tag Info

130

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 reverts to black and white mode. The colour-burst signal - 8 to 10 cycles of 3.85 MHz - is unlikely to be generated by random noise. Figure 1. The colorburst ...

15

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, into b/w mode. For split seconds there might be randomly something that looks like a color carrier might be present, then there might be a quick colorish ...

7

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 $f_2$ (Dual Tone) frequencies are heard at the same time. $f_1$ (rows) and $f_2$ (columns) have four frequencies (Multi-Frequency) associated with them, although 1633Hz ...

5

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 computation of a frequency spectrum is a Fast Fourier Transform. Most software packages have a ready to use algorithm for this implemented. If you have a look at ...

5

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 clearly. The actual design of the bandpass filter is another matter, depending on what frequency range you need and how prevalent the noise is. It may not spit ...

4

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 if you don't wish to read it from me. I don't think that the mesh is tuned to particular frequencies for EM waves. It's just cheaper than building walls out ...

4

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 period must therefore be $T\leq 0.5$ in order not to lose any features of the signal.

4

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 measure at least 2 different values per period. If you would only measure 1 value, a lower frequent signal or even a constant value could fit your measurement. ...

3

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 system to be stable and all of your gains are above that.

3

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 other variable "sticks" until it's pulled the other way. Think of backlash in gears, or the B-H curve of a hard magnetic material. A low-pass filter is ...

3

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, and the energy-disaggregation field is quite young, so you won't find a reliable off-the-shelf package. But you will find current research which will help you ...

3

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 frequencies above 1/2 the sampling frequency. It makes sense for a 'low fi' arrangement to reduce the filter frequency a bit so as to simplify filter design which ...

3

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: $$y_1 = H(u_1), \quad y_2 = H(u_2)$$ $$\alpha y_1 + \beta y_2 = H(\alpha u_1 + \beta u_2)$$ for any scalar value $\alpha$, $\beta$. Your driven harmonic oscillator is currently described in such a way the ...

2

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 way to small for an open-volume system. Even with both of these issues fixed, I doubt you will be able to get significant noise cancellation. The simple ...

2

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 FPGA board are you using? Is this an off-the-shelf part or some home brew hardware? You're not happy with your test results - what are they? Can you post before ...

2

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. Blocking magnetic fields is harder, it takes more layers, of special materials. (I didn't read NHMFL artcile, I'm at home w/ limited download, I'll read it ...

2

(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

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- natural frequency at about 5.5 Hz. In that particular case, the analysis was basically trivial- 20 lines of python, most of which was importing and plotting. If ...

2

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 image below: a single beam of light will be split up into diffraction orders, numbered $n=0, \pm 1, \pm 2, \ldots$. If the incident light beam is a mixture ...

2

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 laboratories, i.e. goggles which physically attenuate at and near the laser wavelength. Despite that patent's claims, I'm skeptical that their grating system will ...

2

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 is about 0.5s or the highest time frequency is 2Hz. So if sampled between 2Hz and 4Hz the processed signal will be subjected to what is known as aliasing. If ...

2

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 "Power electronics and drive" means. "Power electronics" could be anything from a 20W amplifier driving a motor, through a few MW for transport applications (e.g. ...

2

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 off higher-frequencies that contain noise. The filter can be implemented either on time-domain samples or on the frequency domain (after FFT), but if you want ...

2

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. Welcome to digital signal processing. You then said, "I was just expecting some kind of answer for dummies." Okay, Wikipedia says it's a type of filter "designed to ...

2

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 blades: 2P for a turbine equipped with two rotor blades, 3P for a three bladed rotor. source: https://ocw.tudelft.nl/wp-content/uploads/...

2

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 Couleur à Mémoire) worked in a very similar fashion, both had a colorburst signal at 4.43 MHz, superimposed on a blanking portion of a horizontal synchro pulse. ...

2

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 with respect to frequency. A typical example for a low pass filter is presented below. In the image above, the cutoff frequency is 1. Notice that the x-axis is ...

2

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 sinusoidal input (I actually recommend multisine) is suitable to accurately identify the response of a few frequencies. White noise or band-limited white noise can ...

2

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 signal from the phone's mic unit.

1

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 (finite), maybe by collecting the numerical values or other means then you have to follow the next two steps: Step one: Trivial extension Consider the ...

Only top voted, non community-wiki answers of a minimum length are eligible