In signal processing, a signal is a function that conveys information about a phenomenon. In electronics and telecommunications, it refers to any time varying voltage, current, or electromagnetic wave that carries information. A signal may also be defined as an observable change in a quality such as quantity.Any quality, such as physical quantity that exhibits variation in space or time can be used as a signal to share messages between observers. According to the IEEE Transactions on Signal Processing, a signal can be audio, video, speech, image, sonar, and radar-related and so on. In another effort to define signal, anything that is only a function of space, such as an image, is excluded from the category of signals. Also, it is stated that a signal may or may not contain any information.
In nature, signals can be actions done by an organism to alert other organisms, ranging from the release of plant chemicals to warn nearby plants of a predator, to sounds or motions made by animals to alert other animals of food. Signaling occurs in all organisms even at cellular levels, with cell signaling. Signaling theory, in evolutionary biology, proposes that a substantial driver for evolution is the ability for animals to communicate with each other by developing ways of signaling. In human engineering, signals are typically provided by a sensor, and often the original form of a signal is converted to another form of energy using a transducer. For example, a microphone converts an acoustic signal to a voltage waveform, and a speaker does the reverse.Information theory serves as the formal study of signals and their content, and the information of a signal is often accompanied by noise. The term "noise" refers to unwanted signal modifications but is often extended to include unwanted signals conflicting with desired signals (crosstalk). The reduction of noise is covered in part under the heading of signal integrity. The separation of desired signals from background noise is the field of signal recovery, one branch of which is estimation theory, a probabilistic approach to suppressing random disturbances.
Engineering disciplines such as electrical engineering have led the way in the design, study, and implementation of systems involving transmission, storage, and manipulation of information. In the latter half of the 20th century, electrical engineering itself separated into several disciplines, specializing in the design and analysis of systems that manipulate physical signals; electronic engineering and computer engineering as examples; while design engineering developed to deal with the functional design of user–machine interfaces.
Homework Statement
http://i.imgur.com/01AUp.png
Homework Equations
The Attempt at a Solution
Having some problems with this question, using a third + first order nonlinear device to make a multiplier. I'm fine with using a second order, but this one is stumping me. So, I...
A multimeter is used to measure a sinusoidal signal and reads 2V RMS; what is the peak-to-peak voltage of the signal? A mark will be deducted if you do not quote your answer to 2 significant figures.
This is my guess I am not really sure, there is not enough details I don't know how to get...
In our lab we are to measure speed of light by making a light signal travel through optical fiber. At one end there is the transmitter, which will output the light signal into the fiber, and it will also "modulate" the signal. According to my lab manual, "The reason that the signal is made to...
I post to this forum, because I want to analyze this phenomenon with the aid of those who may understand the various nuances of scientific theory, by which such a thing could occur. I do not feel that posting to a forum dedicated to audio/video would yield quality results.
This matter...
I'm still not very confident in analyzing circuits. Here's what I know:
1) v_o=v_IN - v_T
2) id=k/2*(v_IN-v_T)^2
3) v_o=v_S-(k/2)(v_IN-v_T)^2*RS
4) v_o = v_S-id*Rs
iDS = v_o/RS
The answer I chose in the photo was based off of other online discussions. I'm very confused and don't have the...
My mat lab skills are pretty low, basically i want to know how to make a waveform using 1000 points of data.
if the data is for example
y = 1 for 0<n<0.1
y = 2 for 0.1<n<0.5
y = -5 for 0.5 < n < 1
so how could i plot this waveform using 1000 points of data
cheers
Do non periodic signals have frequency? Because my pretty general rule
f = 1/T
says that they have zero frequency.
But suppose i analyze a voice signal. We generally associate a term frequency with them. If you ever had used audacity you might have noticed that the graph is quite...
Looking at this datasheet:
http://www.ti.com/lit/ds/symlink/lm386.pdf
Most circuits near the bottom have a 250uF cap in line with the output.
Would changing this cap affect the audio signal or would it just further smooth out the waveform?
Hi there, I want to modify a equation which is written for Singal to Noise Ratio. Now I want to change for logical interference. But I could not find any reliable source of explanation, " what is the relation between SNR/SINR and interference(Logical/Physical)?"
Hi everyone! This is my first post here at PF after years of on & off lurking!
So, I'll get straight to it. At work (yes work, not HW) I have a forcing function signal that acts on a spring-mass system. When the spring-mass system "tracks" the forcing function, the curves overlap...
Homework Statement
Find the average power of the signal,
x_{1}(t) = 5cos(2\pi t + \frac{\pi}{10}) - 6sin(10t + \frac{\pi}{8})
Homework Equations
The Attempt at a Solution
P_{avg} = \frac{1}{T_{1}} \int_{0}^{T_{1}} 25dt + \frac{1}{T_{2}}\int_{0}^{T_{2}}36dt
P_{avg} = 61...
Homework Statement
S(t) = S(0)e^{-i \pi f_{o}t} e^{-t/T^{*}_{2}}, 0 \leq t < \infty
S(t) = 0, t < 0
Show that the spectrum G(f) corresponding to this signal is given by:
G(f) = S(0) { \frac{T^{*}_{2}}{ 1 + [2 \pi (f- f_{o} )T^{*}_{2}]^{2}} + \frac{i2 \pi (f- f_{o} )...
Hi everyone!
I would like to analyze a biological signal for periodicities using a Fourier transform, i.e., I'd like to get a frequency distribution plot based on a long stretch of signal. Additionally, I would like to be able to mark the positions of certain frequencies within the signal that...
I've been trying to figure out how to get the signal to noise ratio of a completely multiple choice type exam. I can't do it and it's driving me nuts, so finally I found this website and decided I'd ask. :D
Say you let your students take a multiple choice test and you are able to get all...
Homework Statement
Does the upsampling and downsampling have any effect on the amplitude?
consider the following X(e^jw)
Homework Equations
what will be the amplitude of the signals? do they remain 1 or are they to be divided/multiplied by L/M, L being upsampling factor and M...
Homework Statement
11. What kind of frequency components can be observed in the output if a linear system is excited by a symmetric square wave?
12. What kind of frequency components can be observed in the output if a non-linear system is excited by a symmetric square wave?
Homework...
You obtain an image of a 7 magnitude star in a 1 minute exposure. You found that the 7 magnitude star was detected at S/N = 10 in the image. The S/N was too low for your science and you decided to take another image. If you want to obtain a 1% photometric result on this star, what should be the...
Homework Statement
We're supposed to convolve the signal
x[k] = u[k] - u[k-8]
with its impulse response
h[k] = sin(pi*k/4)*( u[k] - u[k-8] )
with the help of MATLAB.
Homework Equations
-
The Attempt at a Solution
The thing is that we don't know how to do this in MATLAB...
I don't have an explicit problem to be answered per se, but what can I do about my signals processing course?
We're only into our 4th week of school, and already my professor has had several lectures on Fourier Transforms. I am lost. Besides basic calculus, trig, and complex number theory...
Turning FETs "off" in presence of AC signal at Drain or Source
Hello,
I have a very interesting problem that surprised me, and as of yet have not been able to find a solution for.
I have two coupled coils. One is being driven by a pulses. The other coil has FET switches to switch the...
I'm trying to control the speed of a computer fan using the radio input from an RC transmitter/ reciever.
The PWM output of the reciever is 1ms to 2ms high and 20ms low, so 10%-20% duty cycle. The computer fan requires a 30% to 100% duty cycle, at 25khz (about a 40uS pulse)
I was thinking of...
I recently did an experiment where I had a T-type attenuator.
It was connected to a 50 ohm load, and as such I used a function generator with an internal impedance of 50 ohms. Doing the correct calculations, I found the source and load impedance were matched to the attenuator at 50 ohms...
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...
Suppose traffic is moving uniformly with a constant density $\rho_0$ when a traffic light turns red.
At time $t = 0^+$, the initial density profile is then modeled according to the figure below.
The resulting wave motion of the disturbance is governed by
$$
\frac{\partial\rho}{\partial t} +...
periodicty -- Sampling of a periodic signal...
I have a doubt..is a signal which is sampled from a periodic signal also periodic?if so then is there a relation beyween the time period of the two?
Hello, I'm having some issues with small-signal analysis of BJT differential amplifiers.
Let's say I have this BJT differential pair and suppose that Q1 and Q2 perfectly match: http://i50.tinypic.com/14ahdgn.jpg
Suppose a small differential input is applied and consider the small–signal...
Hello, I'm looking to amplify a very weak AC signal using op-amps. The problem I'm running into is that I can only operate using a +5V supply voltage, no negative voltages. My AC signal is about 5mV and I need it to be about +2.5V. The AC signal is initally DC baised and is at +3.5V, so I put a...
Hello, I'm studying BJTs and I have a doubt about deriving the output resistance in the small signal equivalent circuit.
Let's consider the circuit below:
To derive the output resistance, I'd write the following KCL:
i_x = i_{rc} + i_c
at this point, every example I've seen says R_o = R_c...
Hello All:
This may be a repeat post - I looked at my history and did not see it.
I am looking for a product ( finished/qualified) that takes a standard Analog signal ( 0-10V and/or 4-20mA) and converts to a PWM signal with fixed but settable; Frequency of ~ 100 to 5000hZ - possibly with a...
Homework Statement
Consider the following discrete-time signal where the samples are represented using N bits.
x(k) = exp(-ckT)μ(k)
μ(k) represents the unit step function and T is the Δ between each sample.
-How many bits are needed to ensure that the quantization level is less than...
Homework Statement
A Hertzian dipole at origin generates a signal in empty space which is detected at a wire loop with position vector;
r=(50m)ez
Homework Equations
Signal is detected by changing magnetic field;
B(t)=B0 sin(2∏ft)ex
Show it is consistent with the Maxwell's solution to a plane...
Hello,
I've been trying to find the answer to this question on the internet but no real luck so here goes:
Imagine a signal My_signal which has two components, the actual signal A which is not constant over time and a noise component, we can call it N, where said noise component has a standard...
I have included a picture of what I would like to be able to make. I know that older phones operate on very specific MHz signals and that the newer ones are 2.4, or 5.8 GHz.
I know there are scanners out there. But the purchase of one could be illegal, right?
So why not make my own, to pick...
I am using the matched filtering technique to extract the data from a heavy noise background in the process of detection of gravitational waves. I calculate the correlation between the experimental data and a theoretical template.
I have been told that the maximum of the correlation function...
For Loop Circuit -- calculate the nth derivative of the signal
I'm trying to design a circuit that differentiate a signal using a differentiating amplifier. What I want to do is to calculate the nth derivative of the signal based on a count I specify. How can I apply the same amplifier to the...
Homework Statement
Hi ,
The problem is how to analysis this signal in terms of time segments to understnd the characteristics/pattern of this signal
Homework Equations
There is no relevant equtions
The Attempt at a Solution
I have tried to use :
RMS
Wavlet
FFT
But which...
Hello All,
I am a graduate student conducting a shallow subsurface geophysics study over closed landfill cells and have run into a bit of a problem with my data collection.
I have ran traverses spaced 10 m apart running E to W across cells with all traverse lines ran twice using two...
Hi !
I want to amplify the output of my hall effect current transducer ( CSLA2CD ). The output of my hall effect sensor is 15.6mVac. And I used a dual rail op - amp to amplify this small ac voltage which the gain is 101 ( as shown in the schematic below ). I tried to simulate using multisim...
Homework Statement
Using trig identities from a calculus book or other, write out the results to the following modulations. State which frequencies exist in the signal s(t).
Homework Equations
a) s(t) = Acos(2∏f₁t) * Bcos(2∏f₂t)The Attempt at a Solution
cos(s) * cos(t) = cos (s + t)/2 + cos (s...
Hello all.
I have produced a square wave with a given frequency (period of about 0.5 seconds). I am trying to match the phase of the square wave with a periodic pulse of the same frequency. I can detect when I have acheved the phase difference between them of zero but I need a way to...
Hey guys,
If I wanted to go about generating just a plain noise signal (don't care what the signal consist of), at a certain frequency (say 10 MHz) what is the best way to go about doing that?
If possible I would really like to use a microprocessor or ARM processor (due to the higher...
Hi,
I have an issue I hope you guys will help me solve.
I need to re-create a problem seen on Rail equipment where high voltage spikes are affecting equipment (resistive load) normally running on 600VDC.
I thought about using a simple RC circuit to produce the spikes over the 600VDC...
"Quantum measurement predictions are consistent with relativity for macroscopic observations, but there is no consensus on how to explain this consistency in fundamental terms. The prevailing assumption is that the relativistic structure of spacetime should provide the framework for any...
I want to what is the actual job of a Control and signal processing engineer. And does he/she has any kind of job type in power plants or energy supplies?
hope to get an answer as soon as possible.
Airer
Since signal processing electronics rely on a constant DC power supply with a supply current that can only be converted into a fluctuating DC current by the switching devices of the circuitry, does an AC input signal coming from a microphone or wireless receiver need to be converted into a...
Signal flow graph, describing a RC circuit?
Hi, guys. This is my first post on this forum!
I'm trying to understand this example in my textbook.
The current and voltage equations are:
where G=1/R, Z(s)=1/Cs, and I1(s)=I1
Then the text says the following signal flow graph can be obtained:
And...
This is actually a continuation of another thread here:
https://www.physicsforums.com/showthread.php?t=618868
I don't want to hijack that thread. But that thread make me think about how the signal travel.
Let's consider a pcb trace on top of a ground plane...which is microstrip. EM wave...