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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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33 views

Is the following system time-invariant or time-varying?

I was wondering if the following system is time-invariant or time-varying $$ y(t)=e^{-t}\int_{0}^{t}e^{\sigma}x(\sigma+1)d\sigma$$ I know that it's not causal, and I think it's time-varying because of ...
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2answers
65 views

Reducing noise that grows with frequency

I have a project in university where my professor gave us the following problem: There is a transducer generating an AC signal with amplitude of 7.5mV and a frequency range from 50Hz to 150Hz. This ...
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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 ...
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26 views

What is the DC component of the sum of phasors?

I am preparing for the written test conducted by IISc Bangalore for admission into their graduate program. I happened to come across a sample paper from 2016, I think. I am struggling to understand ...
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3answers
151 views

Series resistor on digital signal lines [duplicate]

I have seen many schematics using 22 ohm resistor in series with digital signal lines. I was wondering is this always a MUST or there are there some special scenarios where we don't need them since ...
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1answer
102 views

Does this criss-crossed GND plane look like it will function properly?

I'll be using it at 12 MHz and... not the best parts placement resulted in this board layout. So I am asking more experienced people if it will definitely not work or maybe it will. Thanks! edit I ...
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35 views

Impedance Matching and Reflection Coefficient

Consider a real signal generator (Voltage Source Vs, output impedance Zs, reflection coefficient Γs) and a load Zl with reflection coefficient Γl. I was told that we have maximum power transfer when ...
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2answers
62 views

How to get the 741 op amp to work as a linear amplifier?

I'm trying to run the 741 as a non inverting voltage amplifier. I did the circuit in proteus simulation and it works well to get 2x the input signal. For example, if input voltage is 1V, then I get ...
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1answer
48 views

Improve 134.2kHz PIT tag RFID reader range

I need to scan 134.2kHz PIT FDX tags from a range of 5cm to 10cm. So far, I have built custom reading circuit. It has the standard R+L+C in series driven by 134.2 kHz square wave and the output is ...
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0answers
50 views

Can't figure out how book on Trannys gets hfe of CE amplifier when using T-Equivalent and Hybrid Pi Circuits

So I'm reading through it and doing all trhe problems as I have done with 20+ other books like this. The author says this a lot "Although the transformations are quite straightforward mathematically, ...
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1answer
42 views

How is the power calculated for Si(t) in the picture?

The formula I've seen is to multiply the signal by its complex conjugate, then integrate across the time period interval, and then divide by the period. But when I do that I don't get A^2/2
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4answers
105 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 ...
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0answers
66 views

Measuring a small distance via capacitance

I am interested in measuring a small \$d\$ between two objects shown below by measuring the capacitance between the Terminals denoted as T0 and T1: The distance \$d\$ is roughly 1mm +/- 0.5mm ...
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1answer
55 views

Shield ground to metal body or signal ground?

I have a question about grounding. I will have two short shielded cables with signal wires inside, located at the top of a tower. The cables have a grounding wire inside shorted to their foil shields ...
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1answer
28 views

Manipulating SPL

I've performed an experiment on guitar tone - ive used a fourier analysis to find the different frequency components. The idea of this is to find the sound pressure level of the consonant intervals ...
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2answers
399 views

What is signal ground

I encountered signal ground symbol while studying 555 IC Please explain why isn't a simple ground connection used and how does signal ground differ from normal ground. I am a first year undergraduate, ...
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1answer
62 views

Modifying a PWM signal

I have PWM signal from a computer motherboard to control 2 fans, one of them is rated for 3000 RPM, and the other one is rated for 2000 RPM. I'm trying to run all of them at the same speed(for ...
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1answer
41 views

3 wire signal to 4 core shielded twisted pair

So I have some flow sensors, which have a 3 wire interface. The three wires are 5V, signal, and ground. Signal is pulse output that varies between 5V and ground at a maximum frequency of about 200 Hz....
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4answers
909 views

How is it possible to drive VGA displays at such high pixel clock frequencies?

I'm working on a digital circuit using discrete components to drive a 640x480 VGA display in a 80x30 text mode. For a 640x480 display, the pixel clock is 25.175MHz, which has a period around 40ns. I ...
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0answers
37 views

Remove Sensor Voltage Offset ADC [duplicate]

I've got a pressure sensor and a flow sensor. Both have a 5V span, but have a (different) null offset i.e. at zero pressure (gauge) or zero flow they read ~2V and ~1V respectively. I am using an ...
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1answer
53 views

How much slower does a photodiode become in photovoltaic mode?

Take for example this photodiode, the main differences between using it in photovoltaic and photoconductive mode is the rise time and the Dark Current, aren't they?. I know exactly how the Dark ...
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3answers
457 views

How does Internet communication work on a coaxial cable?

In buildings, it is common for the same cable (coax) to be used for pay-TV and the Internet. It makes sense that I can transmit several TV channels on the same cable, since it can be modulated by the ...
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4answers
66 views

How is electromagnetic interference possible when measuring voltage difference?

This question is primarily concerned with audio but it's probably applicable to other areas as well. As far as I understand, EMI is caused by electromagnetic waves adding power to wires as they ...
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1answer
64 views

Confusion of terminology for control systems

I am confused about the following definitions (if there are any): Reference input reference signal setpoint reference I don't understand specifically what they are referring to. Do they refer to ...
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2answers
78 views

Analog sensor nonlinearity near the rails

I am looking into a 0-5V analog sensor. The problem with this sensor is that it will typically swing within 15 millivolts of the power supply rails with no output load. (datasheet p. 4) This ...
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1answer
131 views

How to measure radio signal strength

I am building several types of radio antennas, and I would like to test which is the most effective. I am wondering: What is the best way to measure the strength of the received signal? It is at ~...
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4answers
135 views

Could someone explain dither signal?

I know that regarding proportional valves the dither signal is a signal superimposed on PWM command that actually moves the valve. It improves the response of the valve because the coefficient of ...
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1answer
45 views

Passing usb data traces underneath of DCDC converter

RKZ0505D is a DCDC converter which has maximum 85kHz internal switching frequency. It is placed as large surface of it placed directly on PCB. If USB data lines pass under plastic package of DCDC ...
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1answer
65 views

High PWM frequency weird shape

Using a STM32F407 if I generate a 200 Hz signal it looks like this: If I want a higher frequency, for instance 10 kHz I get this: I am using a PicoScope 2205A, resolution 8 bits at 200Ms/s, ...
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2answers
60 views

Analog signal exchange between microcontroller and PLC

Overview I need to create an analog voltage of 0V-24V for the PLC ( s7-1200) with a microcontroller with operating voltage 5V. Approach I've been doing this research since yesterday. I'll share ...
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2answers
115 views

How to detect a partial discharge in a noisy signal?

I am working on a competition where we are required to detect partial discharges in given signals. Each signal represents a measurement of some power-line voltage. I know that partial discharges ...
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0answers
51 views

NMI Input circuit on a MCU

This circuit is connected at the NMI input of a MCU. The 'J2s' pin is connected to an external signal. Is it some sort of delay circuit or some filter circuit? Edit: J2s is digital signal coming ...
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2answers
77 views

How to decrease nrf24l01 transceiver range?

I've just got my Nrf24l01 but then I found out that the working signal range for the module is 100m and above. Our real intention for the module is to let the nrf24l01(Receiver) out of range for about ...
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1answer
58 views

Desktop PSU registering signal from 220ac input [closed]

Question: Do "current+old" generation desktop pc's have any built-in means of registering a signal that is modulated on a (220v) AC power output? Application/context: Suppose your energy company ...
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1answer
59 views

Random Noise Voltage

I have a signal I am interested in obtaining power from. The best way to describe the signal is that it is random. In the graph, the voltage fluctuates from negative to positive with an RMS of 0.5 ...
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3answers
114 views

Ground Plane Tips for Beginners

I have made a few PCB's over the past few months as I have started to learn about design. All of the circuit boards have been Arduino based, so nothing to powerful. I design them up in Eagle and I ...
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3answers
91 views

How to configure NPN transistor as switch and adjust current flow?

Consider the following circuit: As signal a 100 kHz square wave (between 0 and 5 volts) generated by an Arduino. I want to control the transistor so it will let the current from the supply pass ...
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1answer
63 views

Unnamed bus connections in schematics

I thought I could read schematics, but I have this problem: sometimes there are unnamed signals connected to buses and I don't know where they are supposed to be connected. Example: IC3 pis 14...23 ...
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3answers
417 views

Difference between analog signal and battery voltage

I want to find out if using an analogue sensor is feasible in my noisy environment by running some signal integrity tests before I buy it. Because I don`t have the sensor yet, I need to simulate its ...
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5answers
143 views

Please explain this formula for the relationship between bandwidth and the temporal response of a photodetector

I am reading "Optoelectronic Sensors" by Didier Decoster and Joseph Harari. At section 1.8.2 they start explaining the relationship between rise time and bandwidth, and they give a very weird formula ...
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1answer
123 views

Analogue (or digital) signal integrity with multiple sources of noise

tldr: Can I transmit an analog signal through a noisy environment without it being corrupted, or should I use a digital signal instead? My requirement is to transmit a signal from a MA3 absolute ...
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3answers
112 views

Is there any way to obtain linear or angular distance proportional to a voltage signal?

If we have a programmable arbitrary function generator as a voltage signal source and if we are able to output any waveform like a sine or exponential decay as output voltage versus time; how can this ...
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2answers
53 views

Voltage Equation in Time Domain

When we describe a AC signal (voltage is this case) in time domain we use an equation something like this below: \$v(t) = V_m \mathrm{sin}(\omega 𝑡 + \phi)\$, where 𝜔 is the angular frequency of ...
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1answer
68 views

Creating a custom playback device

First of all, let me apologize if this isn't the correct place to ask this. This is the one of the best places for my question that I've seen so far. I've been designing a box for on my desk that ...
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4answers
142 views

Can I electronically substract an audio signal from an other one?

I encountered a little tricky situation in one of my project. I have two audio signals, A and A+B on two different wires. I would like to know if there is a solution to electronically retrieve the B ...
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2answers
60 views

Graphical nature of signal energy

In signals, we learn that the energy of a signal is the integral of its square. E.g. \$E=\int_{-\infty}^\infty x^2(t) dt\$ We know that integrals are the areas under the function in a graph. But ...
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2answers
29 views

Signal Comparisons: “Orthogonal functions”

When comparing two vectors, if the angle between them is 90 degrees then they would be seen as orthogonal and Cn= 0 where Cn is the correlation between these two vectors representing a signal. What ...
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3answers
106 views

Delaying rising edge of input signal - 3.3v logic

I'm new here and I need help with my project. I working on my DIY home automation and I need to delay rising edge of the input signal. Trigger is faling edge. I need to delay it 100 - 500ms and I use ...
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2answers
69 views

Device that transmits signal to computer [closed]

How would I be able to send a notification or email/msg of some sort to my computer after an event has taken place from elsewhere. To be more specific, when a tripwire is tripped, (LDR/Laser beam) how ...
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2answers
51 views

Testing the RF properties of an enclosure

I need to measure RF (cellular) blocking properties of an enclosure. Is there an off-the-shelf set of tools for doing this? I'm assuming a MHz signal generator and an oscilloscope with an antenna ...