Questions tagged [signal]

A signal is a stream of information in the form of a varying quantity. Usually in electronics, signals can be in the form of voltages, currents, or radiated electromagnetic fields.

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35 views

Time invariance of “y(t) = x(t/3)”

I saw an old homework of Purdue University, in which one part states that system: $$ y(t) = x\left(\frac{t}{3}\right)\;\text{ is time invariant} $$ But I think that is not the case from both graphing ...
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26 views

How to make 4G/LTE signal booster?

I need your advice regarding making 4G/LTE signal booster or some small antenna that would contribute 4 - 5 db boost for 4G signal. so if you can suggest what I can do, but it needs to work. because ...
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21 views

Clarifications on Bandwidth, Bit Rate and Nyquist Rate in Digital Communication [closed]

I do not understand these basic concepts of communication systems. Let's consider a channel in which a sequence of bits is transmitted. If I have understood it correctly, it is a sequence of pulses ...
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62 views

Optical displacement sensor noise and current to voltage conversion

I'm currently involved in a project with the aim of measuring the tremor of mice limbs (displacements of about 100 um). The sensor my group has chosen is TCRT5000 (Vishay), but we are facing several ...
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1answer
80 views

How can I calculate the amplitudes of this signal's harmonics?

How can I calculate the amplitude's of the harmonics? This signal is the voltage of a capacitor bank. There is a few amperes of current on the capacitors in form of PWM. On the signal the 200mV Jumps ...
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38 views

How can I know which constellation diagram has a lower symbol error just by looking?

So for the following example: How would I know which is less prone to error? $$C1=[−3−3j,−3+j,1−3j,1+j,−1−j,−1+3j,3−j,3+3j]$$ $$C2=[−3\sqrt2j,−2\sqrt2−\sqrt2j,2\sqrt2−\sqrt2j,\sqrt2j,−\sqrt2j,−2\...
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1answer
44 views

How do I convert a Eb/No from a dB value to a linear value

So for example how would I convert an Eb/No value of 2dB into a linear value?
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41 views

Resonant Radar — How aspect independent is it?

Resonant Radar: transmitting at a bandwidth that encapsulates nearly the natural resonance frequency of a reflective object in hopes of illuminating it upon return (higher amplitude.) I have read ...
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21 views

How do I plot symbol error rate against signal to noise ratio for m-ary pam modulation in matlab? [closed]

So I am a beginner in matlab and I am running some tests and wanted to know how to plot symbol error rate against signal to noise ratio for m-ary pam modulation in matlab?
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20 views

Discrete time linear time-invariant system Problem, thinking of the questions for days, plz help!

Sorry guys I know this maybe a easy question for you guys, but I have tried days to figure out what happen but I just don't know how to do for part b and c Here is the question: Consider a discrete ...
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4answers
77 views

Rejection of particular frequency in a signal which contains many frequencies in its spectrum (fourier transform)

How does a filter know which frequency is to reject? Detail: A signal may contain a lot of frequencies. How could we surely say that the result of linear combination of the result of applying ...
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1answer
54 views

Does adding the input signals change the behaviour of an amplifier?

I have these 3 signals, they differ by 300 Hz each. When I use any of these signals as input to a class B amplifier, I get the desired current amplification. The thing is, I have to input all these 3 ...
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1answer
19 views

Which are the physical factors that determine the maximum transportable resolution of a cable (for instance: HDMI)?

Which are the physical and electrical factors that determine that an old generation HDMI can transport for instance 1080p resolution, while a new HDMI (2.0) arrives at 4k? Is it due to a different ...
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16 views

Response of a Differential Pair to Differential Mode Signals

I do not understand this kind of analysis of a Mosfet Differential Pair: This analysis wants to prove that, when a purely differential mode signal is applied (so opposite signals are applied between ...
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3answers
47 views

What causes these artifacts in my electrophysiology recording? Large power spikes at many frequencies

I'm a biologist who does a fair amount of computational work, but has little electrical engineering experience, so please excuse my ignorance. I'm recording electromyography (EMG) signals from ...
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28 views

Coding Signals in CDMA

let's consider this picture showing how signals are coded in CDMA. So, let's analyze them step by step: 1) A certain user j generates a signal sj(t) which has a rectangular shape (or in general it ...
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3answers
77 views

What does \$x^*(t)=x(t)\$ mean in signals and systems?

I am often seeing this notation \$x^*(t)=x(t)\$ or similar but I cannot remember when I saw it the first time and I cannot find anywhere that explains the meaning of that notation. What does it mean?
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22 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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2answers
300 views

Why is BER higher for binary modulation compared to quaternary?

I came across this image in my notes and I fail to understand why BER seems to decrease as the modulation order increases and I was hoping for an answer
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1answer
27 views

Input and Output Impedances of Single to Differential mode converter

I have this circuit that converts a single ended input signal to differential output signal. I want to understand how to calculate or find out its input and output impedances? The two op-amps are in ...
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0answers
33 views

Signals Sinchronization in B/W CRT TV

If I have understood correctly, in CRT B/W televisions there are basically 3 signals: 2 sawtooth signals (used for horizontal and vertical scanning), and a signal representing the brightness of each ...
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3answers
144 views

High Speed Signals PCB guidelines [closed]

How quick does a signal have to be in order to be considered a high-speed signal? What are the limits and threshold where you can get away without special PCB layout?
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5answers
126 views

Sampling theorem clarifications

whenever the sampling theorem was explained to me, a situation of this kind was proposed to me. If we look at the previous image we will see that the condition to avoid spectral aliasing is that we ...
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2answers
43 views

Group multiplexer

I've got a project on my Digital Electronics course and I'm stuck. I've got five 7bit sources which I want to choose from by counter and multiplexer. But multiplexer has only one bit inputs and output ...
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1answer
98 views

How to record a speaker?

Complete noob here. I don't need a ready to implement solution, pointers on what to read upon and ideas for even simpler projects to gain experience first are perfectly fine. I'm trying to feed both ...
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26 views

Changing an AC Signal with a MAX9926

We are using a MAX9926 in Adaptive mode to detect zero crossing of a crank signal. Its mode cannot be changed (PCBs made) however we have a particular use case where the signal presented is as ...
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1answer
20 views

Vlsi multi cycle path

In multi cycle path of 3 cycles, the setup for data D1 is checked at 3rd cycle. But for the next data, D2, the setup will be checked at 4th cycle or 6th cycle? I have this doubt because, data takes ...
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1answer
23 views

Gaussian Channel: Capacity and Explanation

Let's consider a gaussian communication channel, which is represented through this scheme: Starting by this assumption it is possible to prove that the channel capacity is equal to The computation ...
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1answer
56 views

Ethernet vs CAN bus physical signal

Reading about Controller Area Networks and Ethernet standard, I cannot understand why there is a difference in the way the signal is transmitted. Both protocols use twisted pair cables to communicate, ...
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1answer
14 views

activating an EC2-3TNU with the VT pin of an HT12D

I am sending a signal from an HT12E through an rf transmitter to an rf receiver then an HT12D. This all works fine and the data signal from the HT12D is sent to a CZH-LABS D-1022A(for filling a pool). ...
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39 views

Composite video signal detection problem?

I have an android headunit and I installed a reversing camera to it. The problem is that the headunit does not seem to detect the camera signal if the environment is too bright. It just shows black ...
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1answer
42 views

how to reduce signal noises

I am trying generate guided waves on simple metallic plate through piezo-ceramic material, I place two piezo on the surface of the plate at the different location and through Arbitrary pulse generator,...
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1answer
23 views

How can an IAR ODE system be dynamic and LTI at the same time?

I'm currently studying a course of systems and signals. we talked about IAR ODE systems and their properties, and I have a question about something I don't quite get - how can an Initially at rest ODE ...
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44 views

Modifying the volume pot in a stereo amplifier

This must be a rather basic question. I have stereo amplifier with a 30K potentiometer serving as a volume control pot (two of them ganged together, to be precise). The pot is connected as a classic ...
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1answer
128 views

Why -3 dB in signal to noise ratio (SNR)

I'm reading about a signal to noise ratio (SNR), I'm quite new to this kind of stuff. $$SNR=10\log_{10}\left(\frac{P_{SIGNAL}}{P_{NOISE}}\right)=20\log_{10}\left(\frac{A_{SIGNAL}}{A_{NOISE}}\right)$$ ...
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2answers
39 views

Plane Splitting - Single winding AC to dual rail on the same board as preamps

So I have asked a similar question and was wondering if I could trouble you guys for a little more advice. I believe I have taken all of the advice from before into account. Ill get right into it. ...
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1answer
62 views

Contact resistance is messing with the transistor switch

Hello I have a circuit board here that detects when a plug is detected on a 3.5mm audio jack and a LED is lit up. Since the audio jack has switches, I am using the ring contact and switch since it is ...
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1answer
97 views

Simulation vs theory in 50 Ohm matched impedance clock lines

simulate this circuit – Schematic created using CircuitLab I'm routing an aquisition system based on 3 high speed ADCs. To trigger the conversion at the same time I planned use a clock buffer ...
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1answer
107 views

why high frequency are blocked by walls but allowing low frequency? [closed]

I recently came across the idea that walls block high frequency signal but it allows low frequency signal. Could anyone explain what is the frequency response of walls and what factor in wall modifies ...
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4answers
1k views

why we need self-synchronization?

I am new to electrical engineering. Just a question on lack of synchronization problem. Below is a picture from my textbook: I am very confused, time is unique to everyone in the world, so if both ...
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2answers
50 views

BNC Connector/Cable Suggestion

I am not an expert in this area and therefore need suggestion regarding what is the best way out for this case. For my experiment, I am installing a camera that requires a BNC based trigger signal. ...
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1answer
24 views

Does DiSEqC require a DC bias?

The DiSEqC (Di[gital] S[attelite] Eq[uipment] C[ontrol] specification (bus_spec.pdf within https://www.eutelsat.com/files/PDF/DiSEqC-documentation.zip) describes a tone-based serial data bus that can ...
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3answers
35 views

Why phase is the position of the waveform relative to time 0

I was reading a book which says: Phase describes the position of the waveform relative to time 0. It indicates the status of the first cycle. and below is a picture I am a little bit ...
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35 views

How does the following signal look like?

What is the meaning of the subscript -1 in the following signal? How does the signal look like? I understand that \$ \sum_{-\infty}^{\infty} \Delta (t-n) \$ is a signal where \$ \Delta (t) \$ is ...
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2answers
75 views

How to interpret the FFT of the mains voltage in this case?

I coupled the 230Vrms AC mains voltage to a scope channel through a 10Vpk-pk step-down transformer. I can imagine the transformer will already filter high freq. noise but I thought I can still see ...
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1answer
46 views

Accurate signal reconstruction

While reading through this page I came across following info: "For accurate reconstruction using sin (x)/x interpolation, your oscilloscope should have a sample rate at least 2.5 times the highest ...
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1answer
56 views

High - Frequency Carrier Necessity

let's consider a basic scheme of a receiver. Now I have two questions: I was told that the presence of the mixer is important since it is useful to delete the carrier frequency of the received ...
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1answer
32 views

What is this “drive circuit” for CCD sensor referenced to?

I had a look at the TCD1304DG CCD sensor which I consider using in a project. The datasheet is pretty lucid, but I couldn't figure out what the following diagram is supposed to say: Is this just a ...
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1answer
83 views

How to extract the switching noise component for this signal data?

A servo accelerometer when powered by batteries has a clean output, but when used with this SMPS supply its output seems like have switching artifacts from the power supply(the datasheet says its ...
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25 views

How to determine received signal strength including reflections?

I have an RF system with known transmit power, transmit antenna gain, receive antenna gain, distance, and frequency (900MHz ISM band). I can calculate direct received signal strength based on those ...