Signals Definition and 434 Threads

Hi, just a simple question. We've always been told that microwave ovens are dangerous and to not stand near them when they're on, obviously because they have the ability to heat up water molecules. I just read that the microwave frequencies they emit are 2.45 GHz. Wifi signals consist of 2.4...

Hiiiiii Everyone , It is My First Post ...And I will be Very pleased if You helped me find a solution to my problem . well... It is a Matlab code & I have different type of signals (impulse ,Ramp, sinusoidal,Dc ,exponintial ) & the type of signal is determined by the user (...

Hello friends.I was just wondering if a step up transformer can be used to amplify voltage signals like a transistor,as it step up input voltage at its output.?

What is the best book out there for Engineering Signals and Systems? One that is clear & easy to understand and has many different problems with solutions. The book I am using has no solutions and there is no way to check my work. I hope someone knows a similar book...

Hi guys, I was studying the proof below and just can't figure out the the first highlighted step leads to the second and I was wondering if you guys can help me to fill that in. (: Thank you so much for your help in advance guys!

Is there a difference between causal signal and causal system ? I got this doubt because consider a system h(t) whose out put depends on present and past inputs only for all t (- infinity to + infinity ) so this system is a causal system now if we treat this as a signal and since it...

Greetings, I have two signals, I need a way of testing whether they go above certain threshold voltages for a period of 0.5 seconds. This must be non programmable. I am a bit stumped o how to do it. I thought of having these signals go into an AND gate and then have that AND gate feed into...

Superluminal signals using quantum entanglement Please consider this thought experiment. Would this provide a means for communicating faster than light or is there an error somewhere in it? SUMMARY: Person B can instantly know whether or not Person A did measurements on his particles by...

In the ZWM study of 1991 Mandel et al get coherence between the signal photons of two distinct downconversion sources. This is shown with an interference collection between the two possible sources of signal photons (even though they are entangled with the idler). This is achievable because...

Hello! We are trying to verify if an acoustic standing wave has been established in a cavity. In order to do so, we are giving a constant frequency signal to a speaker. We are picking up the signal at two locations, one very close to the speaker(reference signal) and at a particular...

I would like to know more about the interactions in nature. Here's an example based on the observation of how radio waves efficiently transmit music from the radio stations. You can carry the radio with you around the city, and the signal never disappears. It seems as though the position and...

1) y(t)=dx(t)/dt Is this system memoryless? 2) y(t) = 0 if x(t)<0 x(t) + x(t-2) if x(t)>=0 Is this system linear? Thankyou :)

Homework Statement I'm confused on whether or not two functions would be equivalent or not. Let's say x(t) is a triangle with height 1, width 1. The hypotenuse of it is the function t (with a slope of 1). I'm told that x((t+2) / 4) then is making it 4 times as wide and left-shifting the...

Homework Statement a) Find the unit impulse response h(t) of an audio system that causes two echoes, one occurring at 0.5 seconds and the other one at 1.5 seconds. Please sketch H(w). (Magnitude and phase) b) Design a system that can eliminate noise coming from the 60Hz power signal (thus...

This paper 'Provocative radio transients and base rate bias: a Bayesian argument for conservatism', http://arxiv.org/abs/1211.7338, discusses transient radio signals as possible signs of extraterrestrial intelligence. I knew of the 'WOW' signal, but, was unaware of other similar detection events.

Homework Statement Consider an LTI system with impulse response h(t) = (0.5sin(2t)/(t) Find system output y(t) if x(t) = cos(t) + sin(3t) Homework Equations y(t) = x(t)*h(t) The Attempt at a Solution I am only familiar with doing much simpler convolutions using graphical...

Homework Statement Let's say I've got simple y''(t) + 2y' + 1 = x(t), with maybe y(0) = 3 and y'(0)=1. the input x(t) is 12cos(20t). Using a laplace transform, determine zero state response of the output y(t). I know eventually I end up with the Y(s) and X(s) form, and then I have to...

Hi PF, Actually the information signal can be represented as real signal. Then why do we go for complex representations? why complex conjugates etc do appear after all? May be some basics is lacking :confused: -Devanand T

This paper - http://arxiv.org/abs/1211.3816 - by Beckenstein is fascinating. I would like to know if the experimental test proposal is realistic.

Hi there, I am looking for books that treat signals and systems from a mathematical perspective. When I say "signals and systems", I am referring to the typical second/third year material taught in EE programs: system characteristics (causality, memory, stability), LTI systems, linearization...

Hi guys:I have a project to design ECG i want to calculate the six leads(I,II,III,aVR,aVL and aVF) by this method: i will measure the voltage of three probe or electrode(RA,LA and LL) RL as a reference by using DAC(digital to analog converter) the DAC connected to PC computer, and...

Homework Statement Given an input signal and the output signal, I used the deconv function in MATLAB and got a vector of what would be the impulse response and a remainder vector. Homework Equations I know this is bad because (in this situation) the input convolved with the impulse...

then how can you tune into, say, 101.1 when its not at 101.1 MHz all the time given the frequency change?

I am having trouble with this homework problem, I know how to get started but I just don't know how to carry through the completion of the problem: Question: Given the Fourier transform of an aperiodic signal X(ω) = 2*sin(3(ω-2π))/ω-2π (a)find its inverse Fourier transform x(t) using...

Homework Statement http://i.imgur.com/j8JdV.png Homework Equations http://i.imgur.com/Wobmo.png The Attempt at a Solution I wasn't really sure where to start with. Can energy level be calculated at any of these, since the signal stretches to infinity? I'm very thankful for any...

Homework Statement See first figure attached Homework Equations The Attempt at a Solution See 2nd figure attached. In part (b) it asks me to sketch the even portion of the original signal. How do I know what that is? I've sketched x(t) in my work and I know that the...

Homework Statement Consider the system defined by Y(s) = H(s)X(s) with H(s) = K \frac{s-a}{(s-b)(s-c)}. Build a function in MATLAB to simulate this system for given values of a,b,c,K and various input signals x(t) (in the time or in s-domain). Include a function to display plots of the time...

Hello can somebody tell me if what I am doing is valid. Ok I have a DVM measuring a AC noise voltage every 0.08 seconds (12.5 Hz) This data is spat out in an excel sheet and looks like this: Elapsed seconds noise voltage value 0 -2.88748E-07 0.079999998...

I'm trying to learn more about how cell phones operate. Right now I don't understand the power involved in the signal between the cell site and mobile phone. I've read that the average cell phone has a signal strength that ranges in between -80dBm and -120dBm. I've also read that cell phones...

Hi all Sorry if this is quite a basic concept, but I am confused about RF signals. The way I currently understand it is that radio waves in space are an oscillating electric and magnetic field at 90 degrees to each other traveling through a medium. However, when you pass a radio wave into a...

Homework Statement Prove whether or not, y(t) = \frac{1}{2}\left( x(t) - x(-t) \right) Is time invariant or not Homework Equations The Attempt at a Solution Shifting the output by -T results in, y(t-T) = \frac{1}{2}\left( x(t-T) - x(-(t-T)) \right) y(t-T) = \frac{1}{2}\left( x(t-T) -...

I have inputed the following, I was given a signal and told to plot it in a time domain. The signal ECG is a data file and imported. N = 15000; fs = 250; t = linspace(0, 60, N); %signal = ecg data = ecg subplot (2,1,1); plot (t,ecg); title ('Time-Domain ECG') xlabel ('Time (s)') ylabel...

Hi everyone, In my signals assignment, I'm asked to show that, for a continuous time, real-valued signal x(t): Ex_even = Ex_odd = 0.5 * Ex So here's what I've done: Ex_even = ∫|(x(t) + x(-t))/2|²dt Ex_even = 0.5 * ∫|(x(t)² + 2x(t)x(-t) + x(-t)²)/2|dt Ex_even = 0.5 * [ 0.5 *...

Homework Statement I just have a general question about what one of my professors had written on the board today in class. He was writing down examples where we had to determine whether the given statement was time invariant or not. One example was written as follows, x(-t) = y(t)...

Homework Statement Suppose h(t) is a causal signal and has the even part h_e(t) given by: h_e(t)= t[u(t)-u(t-1)]+u(t-1) for t>0. Find h(t) for all tHomework Equations For an even function f(x), f(x) = f(-x) Also even functions can be expressed as x_e(t) = 1/2[x(t)+x(-t)]The Attempt at a...

Homework Statement A recursive DT system with input x[n] and output y[n] is given by y[n] = -0.25y[n-2] + x[n] a) Determine and plot the impulse response h[n] such that y[n] = x[n]*h[n] b) how would you classify the system and why? c) What modification, if any, should be made so...

Kindly see the question above. First signal is x[n] Ques 1: we are required to find x[4-n] The way I did, the answer should be (a) but one of the solution says (b). Which is the correct one?Ques 2: What are we to do while finding x[2n]? Consider only 0, 1 and 2 as twice of those gives 0, 2...

The greater the amplitude of a given frequency of light hitting an antenna the greater the induced speed of electricity in the antenna? Reply in simple english please.

The signals broadcasted by radio stations are identifiable because each station has its own frequency that no other station is allowed to use. Is this the same method used in cellphones and in the IP and MAC addresses of computers? Do they have circuits tuned to transmit data only at a set...

Signals and image processing/analysis -- Learning Resources I'm at a mediocre university I don't belong at and can't really transfer at this point unless a great university is willing to break its own rules about deadlines for me for this fall(connections, anyone?!). I suppose I'll just have...

What is the best way to generate a signal with a high frequency (700 MHz - 30 GHz)? Is there a preferred circuit diagram for such a design, or is it better to use a processor of some kind? Is it really heavily based on the length of the antenna (dipole)? I am trying to do it as cheap as...

Why sine wave is the basic building block signal to make other signals? Not any other wave. -Devanand T

why do we use light signals to measure time? In flat spacetime Let's say we have two observers in one's rest frame the other one has velocity v. We suppose each of them sent light signals to other one with time separation of Δt(their proper time) and measure time accordingly.we see time...

I know the peripheral nervous system is all connected at the spinal column. If spinal EEG can be conducted, could it be possible to observe movement of limbs on a EEG chart?

Hello, I have LED's all over my vehicle. I have them as tail lights, in the climate control,door switches, and several more throughout my car. I have this piece called a HYPERFLASH harness hooked up in the system that was recommended to prevent hyperflash, and it has done a perfect job...

http://en.wikipedia.org/wiki/Coaxial_cable http://en.wikipedia.org/wiki/Poynting_vector Could a coaxial cable be used for electric current instead of radio signals? 'For example, the Poynting vector within the dielectric insulator of a coaxial cable is nearly parallel to the wire axis...

I drew a circuit using paint for this function. I was wondering what kind of individual comparator should I use to save the most power. Also, what are some less noob ways of going about this? sorry if stupid question. I am an undergrad

Homework Statement let x(t)=cos(ω1(t+τ1) +δ1) and sin (ω2(t+τ2) +δ2) determine whether both the signal are same for given data ω1=∏/3 , ω2=∏/3 τ1=0 , τ1=1 δ1=2∏ , δ1=-∏/3Homework Equations The Attempt at a Solution solution is as given-: as...

Hi all! First off: I don't know which forum to post this. I'm no grad student or PHD so academic forum seemed wrong, and it's not really just math, since it was the result of a measurment and the signals can come from environment, etc. Ok. I measured the magnetic field using a sensor...

Hi I'm wondering what properties affect the propagation of electromagnetic signals. I am interested why an aluminium case would adversely affect signal propagation, for example in this case, here And why is it that a small gap in that casing will allow signals to propagate? (is the...