Signal Definition and 989 Threads

www.mathpages.com/home/kmath210/kmath210.htm outlines the distinction between phase and group velocities, and why the group velocity of electromagnetic waves going faster than the speed of light c does not mean that information is going faster than c, because the phase velocity will always be...

what is the difference between Fourier series and Fourier transforms ?

Homework Statement The questions states to draw the output voltage (Vo) for two full cycles knowing that we have a sine source with 2v amplitude.Homework Equations The Attempt at a Solution I've found: Ic = 1.303 mA Av (gain) = 1I can't figure out why the output signal gets clipped while on...

Suppose we have a real 25 Hz signal that is sampled at 100 Hz without any anti-aliasing filters. Taking the DFT results in a series of spikes 25 Hz, 75 Hz, 125 Hz, 175 Hz etc. Now suppose the 25 Hz signal after it enters the 100 Hz system now enters a 60 Hz system. If we take the DFT now...

Dear All, We have an voltage amplifier. The input is given in small square wave steps to check rise time and noise level of an output signal. The rise time looks good, but we see periodic (noise)oscillations after reaching the plateau. We measure signal voltage across capacitor (10 micro...

Suppose you want to look at a square wave signal riding on top of a large DC bias. This seems like it should be simple, but I was thinking about this today and I don't know how to do it. Normally, one would remove a DC offset with a high-pass filter (or just a capacitor). However, with a...

Howdy, I am a mechanical engineering student with limited circuitry knowledge to start... Anyhow I have a [-500,+500]lbf load cell that is essentially a wheatstone bridge strain gauge. I want to give it either 9Vdc or 12Vdc excitation voltage since I have a regulated power supply that can...

Shifting 0--5V signal to -2.5--2.5V I have a DAC coming from my micro with a signal that will vary anywhere from 0-5Volts. What are my options of shifting that down so I can get a -2.5 -- 2.5V swing? Thanks!

what is the difference between zero state step response and step response in an linear time invarient system?

I would like to increase the maximum current that a PWM signal from a microcontroller can source/sink from +-25mA to +-500mA. The output should have the same peak-to-peak voltage (0 to 3.3V) and should not be inverted (i.e. follows the input). The PWM frequency is ~30kHz. I have looked...

My understanding of how AC current works is that the current changes direction, so essentially the charges are oscillating back and forth along the direction of the cable. Then since accelerating charges radiate, this produces an EM wave which is what carries the energy. But my problem is...

Homework Statement In moments of arbitrary time interval T, receiver catches the two signals, by one in each moment. Signals can not distinguish if the differences in time between the signal reception is less than t = 0.1T. Determine the probability that the receiver does not distinguish...

hello friends... how to solVe this question...i have found its answer is D OPTION. :smile:

tr(0.1t-3) tr(0.2t-3) p((t-5)/4) compute the energy? As far as i know, i tried to plot the functions and calculate the area under the triangle. but i am not sure that i find the correct answer. Could you let me be sure about the answers? My answers 1st-->5 2nd-->2.5 3rd-->4

Homework Statement Hi, I need to find the spectrum of s(t)=sin(400\pi t) + 0.5cos(12000\pi t) when sampled at 10KHz.Homework Equations Using the Discrete Fourier Transform: G_{k}=\sum_{n=0}^{N-1}s_{n}e^{\frac{-j2\pi kn}{N}} where N is the amount of samples taken in the signal duration which...

Hi all, I have discrete data of a signal but I do not know the periods of the signal. The signal is like a "beat" I guess, but not really sure. I plan to use fft in MATLAB to get it's frequency spectrum and get the 0Hz value as the average of the signal. Is this a bad idea? Any other ways...

hi there i was wondering if you could help me: • explain the factors influencing signal intensity in MRI this is one of the questions in my assignment i was wondering if you could please help me ASAP as I am completely confused!

hi. I have a project in hand. I have to make a 40 Khz continious wave into a burst of signals. for this i am using 2 555 timers . 1st astable circuit and the output goes to the triger of the monostable circuit and then the output of this circuit is ANDed with the 40Khz continious waves from...

could one attach an op amp to a wifi transmitter to amplify the signal? thanks.

Question one Homework Statement x[n] = 5sin(0.22*pi) The root mean square (RMS) value eof a sin wave is known to be A/root(2) where A is the amplitude. If the noise in a system is known to have an RMS value of 0.5, what si the signal to noise ration (in dB) of the x[n] in this syetem...

I am trying to graph the frequency spectrum of a signal over time. To do this, for each frequency I use a filter defined by the following equation: y_n = Ae^{i\omega_0}y_{n-1} + x_n This has a frequency response of \frac 1...

Hi, new here. I'm a physics major undergraduate and just got through a class dealing with special relativity. I also learned about it a bit in high school. My question is regarding Einstein's second postulate that, paraphrased, grants that no particle can be accelerated to a speed greater...

Homework Statement x(t) is a random signal taking the values 1 and -1 with equal probability in each time interval Tn of length T, i.e. Tn : (n-1)T \leq t \leqn T Find the autocorrelation function Rx(\tau) Homework Equations From a quick glance at our notes: Rx(t1, t2) =...

I'm not sure if this is the right subforum. This seemed most appropriate. I have a router & modem at home which I use to get a wi-fi signal across the house. The problem is that the computer is situated at one end of the house. Thus, when I'm in my bedroom, which is at the other end of the...

Homework Statement A spaceship leaves Earth at 12 noon. At that time the spaceship clock is set to be synchronised with Earth time. It travels through space in a straight line at a constant speed 0⋅60 c. A radio signal is sent to the spaceship from Earth at 2pm. A shuttle is launched from...

Hi every body I'm an electerical engeneer with a fair backgraund in telecommunication field.I'm working on a project in which I'm supposed to simulate the whole signal a receiver gets on Earth (from suppose a satellite)with all the specifications like the doppler shift of the transmitted...

small signal diode modelling i understand what it is but when i get asked a question like: if vin(t)=2.5+cos(2*pi*100*t) for 0<t<30 use the small signal model of the diode to predict the output voltage of the circuit i have added. assume the opamp is ideal R=2000 Is=10e-16 so i know...

Physics of creating a "deliver-to-Earth-in-future" signal Hi, Assume we had to send a signal to space so that it is automatically bounced back to Earth at some point in the future (~a few thousand years), i.e a space based signal-time-capsule. How could this be done hypothetically? I am...

Hello, I have a background in Electrical Engineering (bachelors (2006) and masters (2008)). I am currently working in IT but I don't like it and would very much like to get into engineering. When I was in school I really enjoyed my signal processing and communications systems classes...

Hello, This is no April Fools request. I am serious about developing a simple electronics/physics experiment. Sometimes when I post a question I get a very good response, & other times I get nothing. So in addition to getting a few good responses I would like to further correspond via e-mail or...

Would someone be kind enough to explain what happens to the operation of both transistors in both the positive cycle and the negative cycle of the input signal please? I'm having a hard time understanding how this works exactly. What I know is that with no input signal, both transistors have a...

In the presence of the signal molecules, cascades of enzyme activation take place usually by phosphorylation. When signal ceases activated enzymes (phosphorylated or dephosphorylated) are still there, so they can go on doing what they were doing before. My question is how this enzymes are...

Say I enter PHD w/ an outside MS. What percentage of coursework can I usually transfer? How many semesters classes need I retake? I'm thinking of an MS in signal processing in EE, if that makes any difference. thanks.

Hi, I Want to know: High GSM RSSI mean Interference? the reason behind High RSSI ist only Interference? Thanks

Hello all: This is my first post on the physics forum so I am excited to have found such a great community of scientists. My problem is that I have been looking for an embedded board that contains an ADC but has a very good external signal conditioning stage. This will be for a data...

I will state here what I understand in this topic which I am a little confused: If I have 2 sinusoidal signals perfectly in phase, with distinct power levels, say -13dBm and -10dBm, the composition ("sum") of both signals is -8.23dBm. Or, for -10dBm and -10dBm signals, the sum is -7dBm...

mobile "lights" I have seen some light making stickers sold that can be put on your mobile and they emit light when you talk. Am I right that they will lower my chances of getting connected when I am far from the antenna? I mean they must somehow make signal weaker, don;t they?

Each proton has it's own magnetic field so it should effect the magnetic field of all nearby proton whether it is homologous (equivalent) or not. I don't understand how this discrimination arise? How a proton understand - "that proton is like me so I shoudn't ... ... ... " I mean it's...

Homework Statement No problem statement - just the following questions. Homework Equations 1.Display on a CRT is most similar to what reconstruction filter? 2.How many samples are required to represent a given signal without loss of information? 3.What signals can be reconstructed...

First, I'm not an engineer, so I don't know this topic very well. Anyway, we were covering Fourier Transforms in one of my analytical methods class (chem major; NMR was the topic) and the phrase "discrete signal processing" came up. In our particular case, we collect individual points on...

For an engineering project I am trying to place a 2.4GHz RFID tag inside a resin casting of a large seaside pebble. However since the resin is less dense than a real pebble, I need to add some mass of metal (since is is much denser) to the resin before it sets. It is crucial for the casting to...

Homework Statement Given a ramp function x(t) = t*heaviside(t) with the known z-transform ( z / (z-1)^2 ). If the time-domain signal has been delayed by 2 seconds, then sampled with an unknown sampling rate (T). How could I get the z-transform (one-sided) for the discrete signal, for any values...

I want to load a .mat file which contain 500 column of data in it and plot the signal out through the GUI using .m file. Can anyone help me on the code?

This is an unusual question in this forum but I couldn't think of a better place. I'm new to Signal Processing. Currently I'm looking into localization methods using multiple sensors. This requires, I assume, some sort of "controlling" matrix that will eventually approximate the location of...

Hello, I know that you send digital signals using ASK, FSK, PSK modulation. I was wondering though if it was possible to send that same digital signal using FM or AM modulation? If not, I was wondering if anybody knew of any popular ASK or FSK modulation IC's? Thanks!

Sir, I want to convert a 9 V dc voltage into a 7 V AC Voltage at a frequency of 3 MHz. Please help me on this. How can I do that?

Hi all, let's say I have generated some discrete data as a function of time. And when I plot it, it looks like that it is periodic. Is there any scientific way to check whether or not the discrete data is really periodic? And determine the period, if possible? Many thanks.

I want to ask how to process a pressure signal so that the signals can be smoothed / linearized, e.g. integrate, differentiate, rms, additive smoothing?

Hi, I am doing a project on communications engineering. I've done some background reading on CDMA and spread spectrum technologies such as Direct Sequence and Frequency Hopping. My project supervisor has asked me to find out the equation for the signal to interference ratio of CDMA systems...

Suppose that you obtain a one dimension magnetic resonance image from two water-filled cubic shaped containers arranged as shown below. This diagram is a cross-section of the cubic containers in the x-y plane. figure description: -one of cube's is 2 cm wide, the other is 1 cm wide, and...