# 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.

150 questions
Filter by
Sorted by
Tagged with
54 views

### Signal diode to protect high speed data lines

I don't understand this. Could someone explain this to me? I have a hard time imagining how it works. Why would the signal line be protected by connecting the diodes this way? If you get an ESD event ...
39 views

### Signal analog sensor DHT22

What is the change in humidity percentage for every Celsius degree change on a DHT22 sensor? I would like to know the value before it is converted into a digital signal. For example, in temperature ...
262 views

### What is the term for a code that has duplicate or redundant/equivalent symbols?

I'm having a hard time performing a literature search because I can't find the right search terms. I'm looking for what you name a code over some alphabet that treats multiple symbols equivalently. E....
46 views

### How To calculate RSSI parameters in 3G and LTE

I'm working on how to determine the distance using RSSI through LTE and 3G network, but I'm having a problem how to calculate the RSSI at a certain distance
73 views

### How to properly take the discrete Fourier transform of a signal as well as calculate the power spectral density of the DFT?

I'm getting conflicting answers on how to properly represent a DFT and normalize the results as well as calculate the normalized PSD of the time series. For background, I typically work with voltage ...
51 views

### Need help on signals and systems, Fourier representation of a signal

I've got a homework question for my signals and systems class. In the question, we're given the graph of the magnitude and the phase of a continuous signal. Here are the graphs: I have to find the ...
1 vote
55 views

### Attenuation and capacity

Does attenuation affect capacity for multiple narrowband signals? For example, assume there exists a 20 MHz channel with two 10 MHz subchannels. The first subchannel has frequency response 2 and the ...
71 views

### Signal path between nodes in a MoCA network

I'm trying to understand how signals propagate between nodes in a MoCA (Multimedia over Coax Alliance) network. For example, in a typical but simple network, one has a coax input from a service ...
1 vote
42 views

### Missing mathematical step in convolution sum [closed]

I am looking at an example on convolution sums. In the example it states the following: $$\sum_{k=-\infty }^{n }2^{k} = \sum_{m=0}^{\infty }\left(\frac{1}{2}\right)^{m-n}$$ I feel I am missing some ...
663 views

### Intuitive explanation for RMS voltage of discontinous sinewave

A sinewave with a peak voltage of 325.3V. The RMS voltage would be 230V Assumption1: If I were to run this AC sinewave through a resistor it would be the same power dissipated as running 230V DC ...
43 views

### Representation of any signal using unit signal

I was introduced to the unit step signal and told that we can write any discontinuous signal in terms of the unit step signal to omit the discontinuity from the mathematical expression. So if we are ...
147 views

### How to prove property of transfer function for causal LTI system

For causal linear time-invariant systems the degree of denominator must be larger or equal than the degree of the denominator. How can this be proven rigorously?
46 views

### How is noise analysis done in practice

If we identify a signal as a Random Process how do we study it in practice, how to determine its characteristics such as stationarity(whether it is Stationary, Wide Sense Stationary or ergodic),how to ...
56 views

### Can we say "transfer function" is almost same as black box, in context of mathematical modelling of physical systems?

In context of mathematically modelling of physical systems,can we say that representation of a system using "transfer function" form is almost same as black box form? Is it ok/correct? As ...
502 views

### 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.
121 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 ...
1 vote
43 views

### 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 ...
1 vote
117 views

### 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 ...
75 views

### 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 ...
256 views

### 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 ...
382 views

### 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 ...
2k views

### 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?
1 vote
276 views

### 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 ...
2k views

### 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 ...
157 views

### 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 ...
66 views

### 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 ...
1 vote
82 views

### 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 ...
162 views

### 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 ...
44 views

### 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: $$s(t)=\left[\sum_{i=1}^{\infty}rect\left(\frac{t-t_i}{T}\right)\right]\cdot Acos\left(2\pi f_0t+\varphi\right)$$ ...
328 views

### 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....
1 vote
56 views

### 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 ...
114 views

### 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 ...
1k views

### 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....
998 views

### 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 ...
58 views

### 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, ...
46 views

### 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 ...
182 views

### 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 ...
38 views

### 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 ...
4k views

### 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 ...
4k views

### 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 ...
1 vote
613 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 ...
549 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 ...
431 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 ...
1 vote
195 views

### 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 ...
125 views

### 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 ...
55 views

### 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 ...
222 views

### 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 ...
121 views

### 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?