# Tag Info

30

Gain and phase margin are usually applied to systems that are amplifiers of some sort with negative feedback around them. The more negative feedback, the tighter the system is controlled. However, you don't want to provide feedback in such a way that the system will oscillate. The gain and phase margin are two metrics to tell you how close the system is ...

14

Where that additional 5MW of power came from instantly until the power system frequency go down and active power governors speed up the generators (obviously there is a time delay)? The voltage on the line sags when loads are switched on (which is dependent on resistance and inductance in physical wires; if they were superconducting wires, the load and ...

14

A fixed DC signal has information - the DC offset - that would be lost if it were blocked (that is, reset to 0V potential.) The bandwidth of that information is nevertheless 0Hz. This idea comes up in information coding, such as the DCT used in JPEG. Each block is assigned a block-average DC offset at the beginning, and subsequent components are coded ...

10

"Embedded systems" are controllers (or computers) which are DESIGNED INTO (and built INSIDE) of the larger product. As distinguished from general-purpose controllers (or computers) which are separate, stand-alone products.

9

It is possible to make the measurement in a single cycle. The general technique is called 'guarding', and it's the staple technique used by 'in circuit test equipment' (ICT) for measuring components on already populated boards. In the general case, a wanted resistor Runknown is shunted by a parallel path of at least two other resistors, for which a node on ...

9

I've always heard that being called undershoot. And, in this Control Systems magazine article on Nonminimum-Phase Zeros they also call it initial undershoot.

8

The delay function is broken. First of all, you should avoid writing delays with busy-loops. Such delays are unstable, unreliable and non-portable. They create a tight coupling to the system clock frequency. Also in case of sleep modes, they make the CPU consume current needlessly. Always use on-chip hardware timers instead. Now if you insist on writing ...

8

No, do not connect neutral to earth or digital ground. In some parts of the world the mains plugs are not polarized so there is a 50% chance it ends up connecting live to earth or digital ground.

8

I think the correct term in English would be “initial inverse response”. The system initially does the opposite of what is commanded. For example, in this book. So it’s even worse than a dead time from a control point of view. In French, "un départ malin" seems to describe a characteristic that shows up in control of hydraulic turbines, so it is ...

8

When you connect a new load, it becomes part of the larger circuit. The current starts flowing through the new load. This is a transient process and the associated electromagnetic field propagates close to the speed of light through the entire grid - that is, the change will be detected almost immediately in other parts of the Power grid, even at relatively ...

7

For a point of reference developing a reference design for a dual processor server type motherboard typically consumes the efforts of: Three or four board design engineers who own the design and guide its way through development. Testing and verification of the electrical design is part of this work. Four signal integrity engineers performing simulations on ...

7

You have to look for information about RAMS (reliability, availability, maintainability and safety) engineering. Basic RAMS concepts and techniques Failure rate: number of expected failures of a component, assembly or product per time unit. MTTF (mean time to failure) / MTBF (mean time between failures): the inverse of the failure rate. The expected time ...

7

There is pretty much nothing special about the DC bin, since it integrates frequencies around 0 Hz, the bandwidth is dependent on the FFT length, as for the other bins. So it is possible to encode information there in the same way as for the others. The reason it would not be used is usually based on some property of the transmission channel: the channel ...

6

The conclusion of the author is incorrect. It is in fact possible to use step response data to measure a system's transfer function, it's just a bit more complicated. This is done all the time when evaluating time domain reflectometry and time domain transmission measurements. The main issue is that the author defines a step to be "a sequence consisting ...

6

I put on my teacher/professor hat. your text mentions an 8Kb RAM, your diagram shows 16Kb. your ROM has 32 locations, hence it needs more than the 2 address lines you connect to it. Even if you intend to connect some lines to a fixed value, you should how that. the question explicitly asks for the PROM content, which you don't give. Yes, it is a 32x8 table ...

6

The reason why transfer functions work so well for linear time-invariant (LTI) systems (and don't for non-linear systems) is that they are the Laplace transform (or, in discrete time) the Z-transform of the system's impulse response, which completely characterizes the behavior of such systems. I.e., the impulse response, or, equivalently, the transfer ...

6

Poles at infinity are obtained when the order of the numerator is higher than the order of the denominator. Consider a transfer function G(s) with a numerator of order n, and denominator of order m, and with n>m. There will be n finite zeros and m finite poles and, as s->infinity, the m poles will cancel m of the numerator zeros leaving (n-m) zeros, ...

5

Use a motor driving a worm-gear reduction with the string locked to the output shaft. In order to tension the string, turn the motor ON in the proper direction until the required tension is achieved, then turn the motor OFF. The worm gear will then keep the string under tension with no power applied to the motor. In order to release the tension, turn the ...

5

$\operatorname{rect}(\cdot)$ is a function that has value $1$ if whatever appears inside those parentheses (it's called the argument of the rect function and I used $\cdot$ instead of some algebraic variable as a place holder) has value between $-\frac 12$ and $+\frac 12$. Otherwise, when the argument is strictly smaller than $-\frac 12$ (or ...

5

May I add a 4th answer in short? 1.) A circuit with feedback is unstable in case the loop gain has a phase shift of 360deg at a frequency where the loop gain magnitude is still larger the 0 dB. Note that this phase shift includes the inverting properties of the inverting terminal. Taking this phase inversion NOT into account (as this is done, normally, in ...

5

People tend to make this way too complicated and difficult to understand. Stability margins are only defined for an ideal, linear transfer function model - a model expressed in terms of rational function of polynomials in the complex variable, s. In a feedback loop with a forward transfer function G(s) and feedback transfer function H(s), the input/output ...

5

Is the nominal model the desired model? (i.e. do we want to reach it?) In much the same way as I'd like a rich stranger to die and bequeath $100 million to me, yes, it's the desired model. Is the nominal model an imprecise idealization of the plant to simplify the mathematics? The nominal model is somewhere between your best guess of how the plant ... 5 We can't simply connect a huge load to a power system without informing the authorities(5 MW is really a huge load) When such a huge load is connected to the existing balanced grid, the grid will initially try to satisfy the load requirements. As a result, the voltage and frequency of the grid will drop as the system doesn't know about the But the Automatic ... 5 There are always small fluctuations in both frequency and voltage in the electrical grid. The size of these fluctuations depends on the power of the generators in the grid as well as the load currently present and the load being added. Under normal circumstances 5 MW is not a big load compared to the load normally present in the grid. For example a train ... 5 Setup I'll keep this short, mostly because I don't know that for which you are ferreting. With KCL, you have:$\$\begin{align*} C\frac{\text{d}\,v_{_{\text{O}{\left(t\right)}}}}{\text{d}t}+\frac{v_{_{\text{O}{\left(t\right)}}}}{R}+\frac{1}{L}\int v_{_{\text{O}{\left(t\right)}}}\:\text{d}t&=\frac{1}{L}\int v_{_{\text{IN}{\left(t\right)}}}\:\text{d}t \\\\ \...

4

What is the physical meaning of "first" and "second order"? ... How do I know if a system is first or second order? A 1st order system has one energy storage element and requires just one initial condition to specify the unique solution to the governing differential equation. RC and RL circuits are 1st order systems since each has one energy storage ...

4

The order of a transfer function is determined by the highest order of the denominator. This order gives the number of poles and - thus - determines the roll-off characteristics of the transfer function (magnitude) as well as the amount of phase shift for rising frequencies. The standard form is very important because it allows to find characteristic ...

4

Yes, you certainly can have three of your DTMF decoder circuits connected to your microcontroller. However, even though the three telephone lines nominally share the same ground (somewhere), you should really treat them as "floating" with regard to your decoders, and use a transformer to couple the audio from each line to the corresponding decoder.

4

Assuming that with "associate" you mean "put in series" that is you hook S1 output to S2 input then you are not doing anything wrong. Problem is that sometimes (plenty of times) solving a convolution integral is not a piece of cake thus you prefere the Laplace transform. Let's start by computing $G_1(s)$ and $G_2(s)$: $g_2(t)=e^{-\alpha t}u(t)$, but \...

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