Signal Definition and 935 Threads

Am getting actually puzzled about some facts from telecommunication. When signal are transmitted from two mobile phones, the signal which is converted at the sending end from analogue by the speaker into digital on the mobile phone, does the transmitted signal actually wirelessly i mean is in...

Homework Statement If the received signal level for a particular digital system is -151dBw and the receiver system effective noise temperatyre is 1500K, what is E_b/N_o for a link transmitting 2400bps? solution says: (Eb/N0) = –151 dBW – 10 log 2400 – 10 log 1500 + 228.6 dBW = 12 dBW My...

Homework Statement 1. i need to obtain the result of x[n] * x[n] (convolution) where x[n] = δ[n] + δ[n-1] 2. I need to obtain the power of the signal x(t) = 4 cos (ω0t) + 2 sin (ω0t) + 2cos(4ω0t) for R = 1 k Ω Homework Equations 1.Who do you convolute 2 diracs ? 2. what is the correct...

Homework Statement The problem is to sketch the signal over time: x(t)=1+δ(t-2)+δ(t+2)+δ(5) Homework Equations N/A The Attempt at a Solution I'm not too sure how to begin this. Would it look like a square wave with different "peaks" over time?

I'm setting out on a project, and I need some basic direction. I am a programmer by trade; my father is a mechanical engineer who is pretty good at electrical circuit design as well---together we want to control a pipe organ by computer. The organ is already operated by electrical solenoids...

I'm utterly confused about this concept and the textbook quite efficiently confuses me further. I'll just try to explain it with an example: The circuit has a V(cc) = 10 V and V(ee) = -10 V. V(c) = 2 V, V(e) = -1.7 V, V(b) = -1 V, I(c) = 1 mA, I(e) = 1 mA. It says that allowable signal...

I was trying to use the Ortec Aspec-927 MCA with Maestro-32, and realized the PMT signal is too weak for it to detect. I passed the signal through a 16-channel amplifier, yet it is still not detecting anything. I passed the output from the PMT into an oscilloscope, and the PMT is working just...

Homework Statement x(t) = e(-2t) * u(t) Ex = x2(t) dt Attached is the work I have done. Got stuck towards the end.

Homework Statement Sketch the signal: x(t) = 2^(-t*u(t)) over (-1 < t < 1) The Attempt at a Solution Attached is an excel fine with my work out. I want to know is it is correct.

Suppose you design the digital circuit with D-flops and need to deal with asynchronous signals. Typical logic is receiving the async signal with a D flop followed by another D flop to deal with metastability. But how does double flopping benefit against the metastability ? The first flop gets...

Hey, I'm hoping this thread can clear up some confusion I have with complex signals and moving back and forth from physical signals to the mathematical models. I'll probably ask some questions specifically, but if you would like to help me please treat this whole post as a question because I'll...

I have read in several places that monochromatic light cannot convey information; e.g. in http://www.mathpages.com/home/kmath210/kmath210.htm. it is stated that "in order to actually convey information, a signal cannot be a simple periodic wave". But doesn't all light have the energy hf? And...

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 ?

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...

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...