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Questions tagged [signal-theory]

Anything related to signal theory, i.e. the branch of applied mathematics and engineering studying the properties of signals and the mathematical tools used to manipulate them.

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1answer
46 views

Long Distance High Speed Wireless Data Transfer

What kind of device can I use to transmit data at a rate of 1MB/min up to a distance of 100 miles? If that's not possible, what's the farthest distance to which I can transmit the data.
0
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1answer
36 views

Contradiction while using the convolution sum for a non-LTI system

In a recent quiz, we were given the following problem: The cascaded LTI systems \$\mathcal{T}_1\$ and \$\mathcal{T}_2\$ respectively have impulse responses \$h_1 \lbrack n \rbrack = \delta\lbrack n ...
4
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4answers
110 views

Sampling Theorem and reconstruction

I do not understand a concept about the Nyquist - Shannon sampling theorem. It says that it is possibile to perfectly get the original analog signal from the signal obtained by sampling if and only ...
5
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3answers
144 views

Why the Wien Oscillator output is a sine?

I don't understand why the output signal of the Wien oscillator is a sinusoidal waveform. I can easily understand how a sine waveform can be generated by an oscillator which contains an LC circuit (...
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0answers
42 views

Derivation of the Shannon Limit

I am doing the derivation of the Shannon Limit, and I think I ran into a snag, and am in need of a bit of assistance: Background: From information theory, we know that the Shannon Limit is: $$C = W *...
2
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1answer
50 views

How to use my bits to transmit this photodiode signal in the most efficient way possible? [closed]

Suppose I have photodiode with a Dark Current of 5 pA and that using the NEP of that photodiode at some frequency \$\lambda\$ I determined that the smallest signal I could detect was of 1 pA. First ...
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0answers
29 views

Calculating reactive power given u(t) and i(t)

I would like to calculate the reactive power of a given two-pole which has the following voltage and current characteristic. \$u(t) = 2+5sin(\omega t)+2sin(2\omega t+\frac{\pi}{6});i(t) = 10+3cos(\...
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1answer
30 views

Why microstripline is compulsory to generate high frequency signal in the range of 2 Ghz or more

I would like to understand why the UHF (Ultra High Frequency) band in the range of 1 Ghz or more like 2.4 Ghz or 2.6 Ghz require microstripline to generate such signal frequency? Is there any ...
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1answer
37 views

Find admittance( G ) matrix of a resistive circuit

I am taking Signals And Systems class where I have to calculate the admittance parameter of a given circuit. A given circuit for example: This is tedious and calculating the parameters takes so long....
0
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1answer
127 views

How do you visualize the frequency spectrum for a digital waveform? [closed]

How does the mathematics of a single or periodic rectangular pulse help us quickly visualize the frequency spectrum for a digital waveform? Develop the ideas behind this. My professor posed this ...
2
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0answers
40 views

What is the signal-noise model of laser induced fluorescence?

The following image is an example of a fluorescence signal trace from the photomultiplier tube detector (PMT). Each spike represents one fluorescently labeled cell. This signal model is definitely ...
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0answers
35 views

Question about time invariant systems

So, as per projectrhea Going x[n] -> System -> Delay results in what I would expect. However, going ...
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4answers
78 views

Is a voltage signal we observe on scope made up of only cosines?

Pardon me for the dumb looking question but I'm trying to comprehend a "signals and systems" subject and relate it to voltage or current signal. A periodic signal is made up of sinusoids which is a ...
0
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2answers
98 views

Does a splitter still reduce signal if only 1 of its ports is used?

I'm using a Wilson Electronics signal amplification system to try to get phone signal in my house. I'm going to attempt using a coaxial splitter like this one to split the amplified signal to multiple ...
3
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2answers
3k views

How can I determine the order of filter?

This is my first study about signal analysing. I'm very confused about filter order. My problem is how can I know whether its 4-th order, 12-th order, or 2nd order like the book says so? I'd like to ...
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0answers
34 views

What effects limit throughput of a short channel?

In a short channel, e.g. a 1" long Ethernet cable, which effects are most likely to reduce throughput and why? What would the nature of the throughput reduction be? Specifically, I am wondering about ...
1
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1answer
151 views

What is the difference between SNR of a wideband system and the SNR for a narrowband system

I was reading Wireless Communications by Andrea Goldsmith in the book the author has stated that the Noise power for a wideband system with Bandwidth B is (B*N/2). Could someone help me understand why ...
7
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3answers
881 views

Why the resultant period of two signals is the LCM of the individual period of that signal? [closed]

Suppose a signal is constructed using two independent signals(say S1 and S2)both S1 and S2 have two different individual frequencies.The resultant signal that has been constructed has a new frequency,...
0
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1answer
76 views

Radians and Degrees Preference

In electronics engineering which is the better unit to work with radians or degrees?What are the advantages those 2 unit provides?
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2answers
167 views

Composition of a signal

Today in our signals and systems lecture we were going through a particular problem then our professor took a signal and broke into its constituent parts he drew this diagram------ Horribly out of ...
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2answers
505 views

Role of complex number in electronics [duplicate]

Complex numbers contain imaginary numbers as we all know but often it is used for solving real life practical problems such as taking the impedance of a capacitor, inductor etc. Even in Signals and ...
2
votes
2answers
374 views

Should the error term of PID be normalized?

By "normalized", I mean +/-1 ~= the maximum error the system can reasonably be expected to experience, or divided by the setpoint. Background: I am working on a PID controller for an SSR heater ...
0
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1answer
111 views

cross correlation reverse order

I have a quick question. I was wondering about the order of cross correlation of two signals. Suppose there are two correlated signals. \$y(t)\$ and \$e(t)\$. Does the following expression hold? \$...
0
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1answer
566 views

Discrete time domain, Is cos(2n) periodic?

I have just started out learning the basics of discrete time. I would like some help to understand if cos2n is periodic or not. I know the discrete time formula for periodicity: x[n] = x[n+N]. I Also ...
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1answer
65 views

Time Reversal of a signal and convolution sum

Why do we often time reverse the impulse response of a signal while performing convolution sum?It can be done even without time reversing the impulse response. By time reversing the impulse response ...
3
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2answers
75 views

Why did my textbook use signal energy as a measurement of approximation error, instead of something else?

TL,WR: Why do we use signal energy as a measurement of an approximation's error, and not something "simpler" like the absolute value of the error? Background: I'm reading through my textbook for my ...
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4answers
566 views

How is “signal strength” characterized on a coaxial cable?

I've come across the Shannon-Hartley theorem, so I assume that a "signal" must have some notion of strength or "power" that can be referenced to some noise level (and whose power can be varied at the ...
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2answers
2k views

Through-Glass WiFi Antenna

I used to install a lot of in-car UHF radios & hands-free cell phone kits. I mostly worked on trucks & commercial utility vehicles fitted with bull bars, upon which I would mount a big, bulky, ...
1
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2answers
484 views

Solving Difference Equation Using Z-Transform

I was trying to solve a problem given in my textbook. I have attached the solution given in the book. I thought some modifications where needed to it and tried to solve in a different way. I ended ...
3
votes
2answers
182 views

Signal System Basics

This is a problem which was asked in paper recently. The final answer they gave was option(A). Since, in frequency domain we can multiply signals. I assumed option (A) and started drawing signals ...
0
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0answers
35 views

Modelling this differential ended system for SPICE simulations and grounds

Considering above illustration, imagine a voltage measurement by a voltmeter where the voltage is coming from a differential output device i.e a device which sends mirrored voltages according to its ...
3
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1answer
1k views

Wireless signal reflection/absorption on different materials

I'm trying to understand the characteristics of RF signals/waves in different environments. I am wondering if there is any data out there regarding how much a wireless signal reflect from an object or ...
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1answer
60 views

Rectangular signal

Can someone explain me how do I take the first derivative of the given function and how will this function look like ?
1
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1answer
294 views

Classify Signals (Static vs Dynamic) Homework Assignment

For the following assignment, I only want to see if I am on the right path when answering the question. The following question ask: let x(t) be the system input and y(t) be the system output. ...
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2answers
53 views

How are higher dimensional sphere packings used in signal transmission?

How are higher dimensional sphere packings (HDSPs) related to the error-correcting codes used by cell phones, space probes and the Internet for signal communication through noisy channels? HDSPs ...
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2answers
298 views

Fundamental Minimum Noise Floor

I am interested in what are the fundamental limits for communication, theoretically of course, practically there many be many other limits. So I have tried to formulate a minimum noise floor for a ...
0
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1answer
115 views

S/N Formula with probability

Hello I am looking for the S/N formula that incorporates the probability of catching the signal, and setting an arbitrary treshold level above which we detect the signal. I can't figure out the ...
3
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6answers
508 views

Are oscillators always non linear?

From linear systems theory, self-excited sustained oscillations are only possible by means of a marginally stable system, where poles are located exactly on the imaginary axis. However, such a ...
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3answers
124 views

Is the Signal-to-Noise ratio arbitrary?

It looks to me that the Signal-to-Noise ratio (SNR or S/N) is completely arbitrary and it's set by the user according to his preferences. Sorry I am amateur on the subject but I don't see any ...
21
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8answers
4k views

Is it possible to receive information if the received power is below the noise floor?

This relates to my previous question, which I think I have asked in the wrong way: How to insert background EM noise into pathloss equation? I wasn't really interested in detectability of the signal,...
0
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2answers
118 views

Convolution integral for LTI system

We know that any continuous time signal can be expressed as follows: $$x(t)=\int_{-\infty}^\infty x(τ)δ(t-τ)dτ$$ I came across a certain relation regarding linear time invariant systems . Using $$x(t)...
0
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1answer
733 views

period of composite signals

I've just started studying basics of signals and systems. I have trouble understanding fundamental period of composite signals.The examples are below. 1) X(t)= \$\\2cos(t)\$ + \$\\cos(t/3)\$ I've ...
2
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3answers
616 views

Why do we need the Fourier transforms of sin and cos? [closed]

As we know we perform Fourier transform in case of continuous and "non-periodic" functions, while sin and cosine both function is "periodic" function then why we perform Fourier transform of sin and ...
0
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2answers
421 views

Finding average power signal and its calculation

Maybe I missed the critical section of fundamental of calculus. I don't get intuitively why finding average power is different if you separate the region like 1,2 and calculating the average of two ...
1
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1answer
375 views

Filter construction: Nonperiodic frequency response

I am confused about the construction of filters for non-periodic signals which attempt to limit the output to a certain frequency range(by frequency I mean with respect to the Fourier Transform). ...
0
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1answer
103 views

Derivation of discrete-time steady-state and transient response

My discrete-time signals textbook (Oppenheim) jumps through the derivation of steady-state and transient LTI system response to a complex exponential input- $$y[n]=y_{SS}[n]+y_t[n]$$ It says, given ...
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3answers
201 views

Explanation why dc-dc converter is a time-variant system

How do you explain that dc-dc converter is a time-variant system? I see that there is an explanation as follows: dc-dc converter is a time-variant system because its topology changes with time. ...
0
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2answers
666 views

How to check a discrete time system if the following is linear and time invariant?

I have the following system: $$y(n) = x(n^2+n)$$ where x(n) = 1 if 0<=n<=3; 0 otherwise. I tried doing the usual check if yd(n) = y(n+d), but that's not giving me the right answer. Anyone ...
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1answer
67 views

Signal conditioning of conductive polymer

I have a conductive elastic polymer which gives the resistance change of 800 Kohm with the input strain of 250%. and also gives linear response when the force is applied. I wanted to have a signal ...
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1answer
49 views

Signal Conditioning of the conductive Polymer? [closed]

I have a conductive piezoresistive polymer which gives the resistance changes according to the applied force and strain. What could the first step to start the signal conditioning. The goal of the ...