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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Duty cycle of CW-tone

How is the duty cycle for a CW1-tone defined? A CW-tone has a duty cycle of 1, but how can you define the duty cycle for a sine-wave? 1Continuous Wave.
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2 votes
2 answers
105 views

Good way to obtain voltages along (non-uniform) \$RC\$ line

I have a long RC line, e.g.: simulate this circuit – Schematic created using CircuitLab Is there a good way to obtain the voltages on nodes V1, ..., Vn (possibly approximated) at a specific ...
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How do you sketch a signal given by x(t) = A(t/T) for time period 0 to T? Does t/T simply denote that the signal covers entire duration of T?

Does t/T simply mean that the signal has magnitude A over the entire "T" duration? Or does it mean that it covers only a fraction? How will it look? I tried assuming A to be some magnitude ...
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1 answer
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Difference AC signal and small signal / DC Signal and Operation Point

What is exactly the difference between an ac signal and a small signal? Or analogue between a dc signal and operation point. I've understood ac signal as a signal with a frequency > 0 Hz and dc as ...
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Distributed Bayesian Detection with a two sensor tandem topology and unknown parameters

If you don't know the correct keyword, you can still miss a key literature search: I have a problem in distributed Bayesian detection with a serial (or tandem) network topology. The probability ...
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2 votes
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Why does a cosine function have a non-infinite Fourier coefficient?

I took my signals class a long time ago and have gotten used to using Fourier tables for a lot of things. I'm reading a textbook on communications and I stared at the Fourier transform equation for a ...
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How are filters able to pass frequencies correctly when multiple signals are present?

I have absolutely no experience in the world of EE but I'm self studying and I have some questions on how filtering works when multiple signals are involved. I understand the graphs of filters showing ...
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1 answer
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How can we determine if a system is time invariant or not?

I am trying to figure out if the system in the diagram (part a) is time knvariant or not. When the input is shifted the output is shifted as well, so I am thinking the system is time invariant, but I ...
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Difference between Message and Signal in Communication Theory [closed]

What is the difference between a message and a signal in Communication Theory? It seems to me that often they coincide, is this always?
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2 answers
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Change range of a DC signal without changing the offset with op amps

I have a voltage signal with the following range: low - 2.5VDC middle point - 2.725VDC high - 2.95VDC I would like to condition this signal to: low - 0.4VDC middle point - 1.65VDC high - 2.9VDC I have ...
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What is the relationship between the number of bits and the sample rate?

Ok, so this topic keeps confusing me. I know that the number of bits is related to the vertical levels. The more bits, the more vertical levels we have. If we have a sample rate of 4 samples per ...
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Strict sense stationary signals and IID joint random variables

I have a questions about strict-sense stationary signals. I know that the cdf and pdf are non-varying in time for SSS signals. However, is the reverse also true? That is, if the pdf and cdf of a ...
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Dual state variable filter HP24 output

So I've been playing with 4-stage state variable filter (SVF hereinafter) to get a voltage-controlled filter with Highpass 24db/octave (HP24), LP24 and BP12 outputs. Unfortunately, reading about these ...
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Finite-duration signal in the time domain, means what exactly in the frequency domain?

I'm trying to understand exactly what restrictions a finite duration time domain signal has on its Fourier transform. I found a helpful table in The Fourier Transform and its Applications by Ronald ...
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Is it possible to syntethize this Voltage Transfer Function?

I have the following voltage transfer function: $$ H(s) = \frac {a s^4 + b s^2 + c}{p s^4 + q s^2 + r} $$ Where \$a, b, c, p, q, r\$ are all real constants. The only method I have been taught to ...
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What happens if the signal frequency exceeds the sampling rate?

As the title states, I was wondering what happens to the frequency contents of the sampled signal of a pure sinusoidal signal that exceeds the sampling rate. I am familiar with the shannon theorem and ...
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Which is the bandwidth of an analog PAM (needed to design an amplifier)?

in a university test, I've been asked to design an amplifier for the following signal: $$s(t)=\left[\sum_{i=1}^{\infty}rect\left(\frac{t-t_i}{T}\right)\right]\cdot Acos\left(2\pi f_0t+\varphi\right)$$ ...
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How do I compute the required bandwidth for a given bitrate of digital TV signal?

In this Encyclopædia Britannica article, there is a paragraph which introduces why video compression was needed to switch from analog to digital television broadcasting. It gives the following example....
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1 answer
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Confusion regarding terminology [closed]

Originally i asked this question on DSP SE yesterday but untill now couldn't get even a single comment so I am reproducing my question here as bigger audience is available here and also my question ...
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2 answers
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Can signals pass through a single wire in both directions simultaneously?

Can electric signals pass through a single wire in both directions simultaneously? To be clear, I mean signals that are not somehow modulated to avoid interference. I also mean a wire, and not a ...
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4 votes
3 answers
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What is the physical significance of skewness and kurtosis of an eletrical signal?

I understood the mathematical meanings of the skewness and kurtosis. But when we calculate these quantities for a signal (say an electrical voltage signal), what physical meaning do they convey? For e....
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2 answers
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How do causality and stability affect the response of a linear time-invariant system?

Suppose that there's a linear time-invariant system with the following transfer function: $$H(s) = \frac{1}{3(s-2)}-\frac{1}{3(s+1)}$$ If the system is causal and stable, I can determine \$h(t)\$ by ...
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Evaluate signal power between two amplifiers

Let's consider this cascade of amplifiers: Consider the intermediate node, and suppose there our signal has voltage Vx. How can I evaluate that signal power (for instance to calculate the SNR, ...
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About discrete time model for wireless channel

I am trying to understand Section 2.2.3 of the book "Fundementals of wireless communication" by Tse and Viswanath. In this section the authors explain how to go from the continuous time ...
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3 votes
1 answer
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How to modify zeros and poles in a delta-sigma modulator loop?

In this specific case, I am modelling a delta-sigma analog-to-digital converter with a basic loop in which the output V is fed back with unity gain to be subtracted from the previously sampled input U ...
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Calculating the Running Corrleation of two signals in Matlab

I am currently using https://www.eecs.umich.edu/courses/eecs206/public/lab/ to advance my matlab skills. Sadly I am stuck at lab2 task 2. First, i cant run the pcode file to get the proper solution ...
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6 votes
7 answers
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Why is power of a signal equal to square of that signal?

Is there any logic as to why the power of a signal \$\mathrm{x(t)}\$ is taken as \$\mathrm{x^2(t)}\$? I searched everywhere and there's no clue. My professor told: "It's a standard result so shut ...
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5 answers
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Is Gaussian noise equal to white noise?

If noise on a signal is randomly fluctuating in time domain around its mean following a Gaussian normal distribution (Gaussian noise), would this be equivalent to an constant intensity in the ...
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1 vote
5 answers
351 views

Why frequency of a DC signal is chosen as zero? If the period can be anything, isn't it same for frequency?

This is a page from Oppenheim. We can assume a DC signal as a repetition of 10 strips per 10 seconds/10 strips per 5 seconds. Like that, if we choose different periods, we get different frequencies ...
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2 votes
2 answers
316 views

Time Reversal Operation for discrete time signals

For a discrete time unit step signal \$u(n)\$ , if time reversal operation is performed then it becomes \$u(-n-1)\$. Is it true for any discrete time signal \$x(n)\$ such that time reversal operation ...
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2 votes
3 answers
181 views

convolution vs correlation?

Apparently this question looks better for DSP SE but I am posting it here to get answer in simple words for those EE graduates who didn't studied signal processing in undergrad. Apparently as far as ...
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1 vote
3 answers
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Aperiod vs Period waveform Fourier Transform: How does nature understand which is the case?

Today I reviewed the theory behind the Fourier Transform, and I asked myself a question that I couldn't answer to in the process. Theory: A periodic waveform has a Fourier series which can be seen ...
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2 answers
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What is the math behind high FM frequency components being more noise prone? [closed]

what is the math behind the phenomena that higher frequencies are more prone to noise? The use of pre-emphasis to boost the higher frequency components to get a better S/N ratio. Can you provide ...
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1 answer
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Doubt on singular value decomposition

I am studying control systems and I am studying the topic of Singular Value Decomposition(SVD). I have found a transfer matrix of a systemm, and computed its DC gain. Then I have performed the ...
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2 answers
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Why does a pole at high frequencies attenuates noise?

I am trying to understand the concept of realizability for an improper transfer function, and I am struggling to understand some concepts. I know that if I have an improper transfer function, for ...
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3 answers
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How to construct a signal with only unit functions?

I don't understand the solution to this problem. How can I write a ramp function in the form of a step function?
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0 answers
24 views

Cellular communications queuing

Not sure if this is the right place to ask but this is a homework question. Consider a base station in a cellular network. The base station has the resources to handle 7 calls at the same time. The ...
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15 votes
3 answers
4k views

Why do microwave ovens use magnetrons?

With a lot of advancement in solid state electronics and signal manipulation, isn't it easier to simply take high amplitude signals with frequencies near 1 MHz and multiply the signals using diodes ...
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1 answer
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Draw the graph of differential of the following graph

Is is like this? I think there should be impulse signal also in the graph am i doing wrong?
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1 answer
76 views

Represent the given signal in mathematical form

Is this the mathematical form? I highy doubt myself $$ -2r(t+3)+2r(t)+16u(t)-r(t)-2u(t-3)+5/2r(t-3)-5/2r(t-5) $$
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-1 votes
1 answer
251 views

Draw even and odd parts of following signal

I think my odd signal is wrong because odd signal cannot be symmetric about y axis
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1 answer
176 views

Calculating steady state output using Laplace transform

I've tried to obtain the the steady state output with the help of final value theorem and multiplication properties of Laplace transform.But I'm not sure whether I've solved the problem correctly or ...
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1 answer
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Confusion regarding step responses of integrator and differentiator?

I am using matlab to study about step response of integrator and also of differentiator using transfer function modelling technique But i have two confusion, one in case of integrator is that step ...
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1 vote
2 answers
75 views

Determine the output signal given the input and inpulse response

It's been a while since I've worked these types of problems, but I've been working out the following problem for a while now and can't figure out a few details: And here is the solution: ...
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0 votes
0 answers
174 views

Is diode reverse recovery time related to diode capacitance?

The title. Is there some relationship between the two parameters? For example, fast diode recovery time indicates low capacitance, or even farther, can one be calculated from the other? Thank you in ...
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0 votes
1 answer
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Colpitts oscillator: how to reduce amplitude thermal drift?

I have built this circuit, supply ±12V: I am using a LM6172 amplifier. I have found the transfer function of the filter involved: \$H(j\omega)=\frac{1}{1 + \frac{R_3}{R_1} - L\omega^2(C_2+C_1\frac{...
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4 votes
3 answers
231 views

Colpitts oscillator : having trouble while respecting Barkhausen criterion, is this criterion insufficient there?

I'm trying to simulate a Colpitts oscillator. I've determined transfer function of the low-pass filter of this circuit: I reached this expression: \$H(j\omega)=\frac{1}{1-LC_2\omega^2+jR_3\omega(C_2+...
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0 votes
1 answer
46 views

Minimum Shift Keying

"Overall frequency excursion del-f in MSK is minimum frequency spacing between symbols 0 and 1 that allows their FSK representation to be coherently orthogonal". What is meant by being coherently ...
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3 votes
3 answers
740 views

Do I need to maintain source of a signal till it reaches the destination?

If I send a signal through a wire having delay of 10ms, then should I need to maintain the source of the signal till it reaches the destination or can I change after, say, 2ms and send the next signal....
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5 answers
241 views

Why can't all data be sent across 4 wires?

I am aware that USB uses a positive, negative and D+/- wires in order to transmit data. The twisted pair are used to negate the effects of interference and electronic noise. I also understand that a ...
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