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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2answers
34 views

Find the power spectral density?

I don't understand how the graph of H(w) is used to find the equation for H(150) and H(200.)
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1answer
48 views

Limiting small signals to one direction (ideally with passive components)

My setup is as following: I use a Y-Cable for splitting an audio signal to two devices (boxes and earphones). The headphones have quite big speakers so they act also like a microphone - feeding back ...
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1answer
56 views

Why does USB signaling to microcontrollers need resistors

I'm currently trying to make a USB device with the ATMega16U2. On page 187 of the datasheet, there are unspecified resistors between the USB port and the pins of the microcontroller The Arduino Uno ...
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0answers
23 views

Hybrid design that includes satellite phone on to a laptop PCB [closed]

My name is Brzenski and I am an student at college in London, doing Network Engineering and Telecommunications. I am in my final term for an HND and have to do a project. I came up with an idea to ...
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1answer
38 views

How can I combine my knowledge of signal processing with electromagnetic physics? [closed]

Now at University I've learnt both signal processing and electromagnetics, I am curious as to how these two areas can be combined into one. For example, in signal processing you are required to find ...
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1answer
44 views

When is a system's frequency response symmetric?

When is the frequency response of an LTI system symmetric, i.e. which property does it need to satisfy? Does it have to do with the system being causal (I believe this means that h(n) = 0 for n < ...
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1answer
20 views

DDC112 Analog to Digital converter

In DDC112 Analog to Digital converter, its mentioned that its suitable for Low-level current output devices, such as photosensors, and can be directly connected to its inputs. But to increase analog ...
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0answers
27 views

Selecting an rf Signal Generator [closed]

I'm trying to locate a signal generator to purchase. Brand and model open, DC to 20MHz, sine and square wave, any other waveforms is a bonus. 1000W or above (yes, I do realise the costs involved) Age ...
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1answer
31 views

Is there any repeater with power amplifier?

I installed sensor module connected with controller. Those are connected with 6-wire cable, and it consists of 2-wire power(5V & GND), 4-wire signals(0~5V analog). First time, I thought distance ...
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1answer
60 views

How electric signal is converted to more powerful electricity

First a little disclaimer: I've a newbie question which is simple, but somehow I can't explain it to myself. I'm interested in how electrical signals can trigger let's say a movement, which requires ...
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1answer
55 views

Line-of-Sight method of simple code transmitting for outdoors

I'm trying to determine the best way to do this. Basically I'm trying to design a system that would transmit a signal containing a simple code to allow the receiver to identify the source device. It ...
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2answers
38 views

RF Combiner Hardware

I have say, 4 170 MHz signals coming in on 4 BNC cables. I would like to add these signals together. Is there a name for a piece of hardware that does this? Are there any special considerations I ...
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2answers
79 views

How do I drop 19VDC from a 0-60VDC source to get an accurate linear 0-48VDC signal

I've been using the Stack Exchange website for years, but never asked or answered a question, so first I'd like to say thank you for all of the help over the years. On to the problem: I want to ...
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0answers
35 views

Voltage at some point on a transmission line (a power distribution line in this case)

I am interested in knowing the instantaneous DC voltage (ball park) at a capacitor bank on a power distribution line at the instant I interrupt the circuit some distance away. If I interrupt the ...
2
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5answers
113 views

Why do we need transforms (Fourier, Laplace, Z and wavelet etc.) for a signal to analyse?

Why do we need transforms (Fourier, Laplace, Z and wavelet etc.) for a signal to analyse? Is it necessary for practical calculations and analysis?
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1answer
33 views

Choosing the right sampling frequency for WLAN 802.11ac signal (BW : 80 MHz)?

I’ve got a WLAN 802.11ac signal & it’s bandwidth is 80MHz, now I would like to know the ideal sampling frequency for this signal. As per the nyquist theorem , the sampling frequency could be 160 ...
2
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2answers
291 views

Area under Dirac Delta function

What is the difference of the area calculation for the Dirac delta function when using different limits of integration? $$\int_{-\infty}^{\infty}\delta(x)dx = 1$$ but ...
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1answer
35 views

exam problem finding impulse response from a given system? [closed]

I search but i did't find useful way to answer it please how to get the impulse response from a given given system
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1answer
134 views

Why it has used BPSK modulation after OFDM?

I am quite new to OFDM modulation. I am reading this from a tutorial. In one of its parts, for showing amplitude variation of the OFDM signals, there is a graph that has used 8 sub-carriers and BPSK ...
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1answer
132 views

Comparison of Series and Parallel LC Filters for Noise Reduction

Since there are two basic types of LC circuits that can be used for passing/blocking signals, I'd like to know the differences when using series or parallel LC circuits for noise at a known frequency. ...
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1answer
91 views

When is impedance matching necessary? Isn't it much less efficient on all other aspects?

I understand that discontinuities of the physical properties of conductors create reflections much like dioptres reflect a bit of light, but : in which cases does impedance matching become ...
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0answers
24 views

How is 802.11 (Wifi) received signal strength (RSS) measured and reported to software?

I have looked around for a while now to find an answer to this question, but answers I find do not fully answer my question. I found this response interesting from another question on this site. ...
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2answers
57 views

Systems and signals - integration with dirac's function and step function

I'm taking the introductory course to systems and signals and the mathematics of integration using the step function and Dirac's function and For the first integral, I just don't know how to ...
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1answer
50 views

Replace Electret Microphone With Arduino Output

I have the following circuit for a simple FM transmitter. I want to replace the electret microphone with a simple tone generated by an Arduino (or equivalent) that will be broadcast over FM radio. ...
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2answers
122 views

Is it possible to amplify near zero signals?

Is there an amplifier has an ability to amplify any signal down to -500 dBm? If there is not, can it be possible? If it is not possible, what is the weakest ever signal that can be amplified?
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1answer
37 views

Determining whether piecewise function y[n] = {x[n] if n even, -x[n] if n odd} is time invariant

$$ y[n] = \begin{cases} x[n], & \text{if }n\text{ is even} \\ -x[n], & \text{if }n\text{ is odd} \end{cases} $$ My usual way of solving time invariance problems is to do this: $$y[n-m] = ...
2
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1answer
63 views

Finding the Power developed by the Nominal Frequency in FM

Question The sinusoidal signal \$f(t) = \cos(2 \pi f_m t)\$ is applied to the input of an FM system. The corresponding modulation signal output for \$f_m = 1kHz\$, is $$Q(t)=100 \cos(2 ...
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1answer
66 views

VHDL internal signal assignment

I am new to VHDL and tried to implement a simple example from a book, what represents a 2bit register and the testbench. Compiling the files works well, and signals the stimulate the register (reset, ...
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1answer
48 views

How to get BPSK data from I/Q signal

I am using AD8347(0.8 GHz to 2.7 GHz Direct Conversion Quadrature Demodulator) to demodulate a BPSK modulated carrier wave. There is no intermediate frequency used. By feeding the signal into this ...
2
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1answer
77 views

Difference between SINR SNR

I am bit confused between these two terms. I understand SINR is signal to interference+ noise ratio and SNR is signal to noise but isn't interference noise too? Then why have he segregated these two ...
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1answer
64 views

Complex numbers manipulation

I have a complex number s of the form s=[1/sqrt(NN\$_{t})] e^{j\phi_{k}}\$ S\$_{o}\$ is another complex number. It is given that |s-s\$ _{o}\$|<= \$\epsilon\$ where 0< \$\epsilon\$< 2 It ...
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1answer
71 views

Use of Audio Tranformers in Amplification

I came across this ckt to make a wireless ear phones using Infrared Signals from IR LEDs. I am unable to understand the use of Audio Transformer here to amplify the audio signal, instead OpAmps would ...
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0answers
40 views

Linear time invariant system transfer function is known - calculate output signal

Here is my task: a) Calculate and sketch amplitude spectrum of u(t), b) u(t) is input signal for linear time invariant system whose transfer function H(jw) is shown. Calculate output signal uo(t) ...
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1answer
43 views

Sync filter in a lock-in amplifier

I've got two questions: What does a sync filter in a lock-in amplifier? What are pros and cons of using it?
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3answers
151 views

Sin signal from PWM

I wrote a program in order to use Pulse Width Modulation to simulate a sinusoidal signal. Added a low pass filter to get rid of the noise and the traces of it being a discrete signal. Added a half ...
2
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1answer
54 views

Radar maths I and Q components

I have just started work with radars. I read that incoming signal in case of Doppler radar is frequency shifted. On adding it to original signal we get Doppler shift. But we don't do it directly. ...
1
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1answer
87 views

Making Device to Send Data to Smartphones: 100m range, 1kb/s bandwidth, low power

What I want to make: A device that immediately sends a notification if the device incurs a moment of high acceleration. The notification needs to denote the acceleration. There is no guarantee that ...
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6answers
105 views

Converting PWM to bidirectional square wave?

Is it possible to make bi-directional ( symmetrical) square waveform from PWM signal? Im talking about 40 kHz frequency and 0.5v /-0.5v peak to peak signal.
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1answer
77 views

Signal targeting a cell phone

I'm a computer scientist, in college I had a (basic) telecommunications course. I've found it interesting, but had afterwards no opportunity to use apply it professionally, which is of course not ...
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1answer
51 views

Digital filter implementation

Digital filters work on digital data. When we implement digital filters in hardware, does that data which was stored in the form of bits needs to be converted back to its quantized voltage level? If ...
0
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1answer
41 views

Connecting GPIO and SPI signals via cable

There is a requirement in one of our systems to transfer signals from one board to another board in the same system. The signals are GPIOs and SPI lines from I.MX6 processor and it is in 3.3V ...
0
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1answer
40 views

Hardware Implementation of Discrete time Systems

Discrete systems work on sampled signal values. Suppose if we want to implement such a system like a discrete amplifier (i.e., \$y[n] = A\cdot x[n]\$), how do we make sure that the input to this ...
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1answer
84 views

Radio signals blocked by red bricks / aluminum insulation

Do red bricks home/building and aluminum insulation diminish the strength of radio signals?
1
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1answer
43 views

Nyquist Sampling rate

We have \$z(t)=\cos(100πt)\cos^2(500πt)\$ . Find Nyquist sampling rate. Well, I know that \$f_s=2f_{max}\$. My main problem is that I am not entirely sure if I could re-write the above signal as: ...
0
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0answers
70 views

Simplest signal level/clip LED indicator?

I was looking to modify a circuit that would take a signal from a guitar, impedance-match, amplify and bias it so that it would be readable by the ADC of a micro-controller, effectively based off this ...
1
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1answer
79 views

Output resistance of Emitter Follower

I have to measure \$R_{in}\$, the input resistance seen by the signal. It was told me, that the quickest way is measuring the voltage gain using oscilloscope, insert a resistor before \$R_B\$, ...
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2answers
92 views

Internal resistance of signal source

It was told me that a signal sent to the circuit can be rapresented by \$V_{sig}\$ and \$R_{sig}\$, where \$R_{sig}\$ is the internal resistance of signal source. Now, let's consider that we have a ...
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2answers
63 views

Singnals, filters and power output

I have couple of questions: A square signal goes through a low pass filter and in the output of a circuit we get a sine. What happens there? Give a scheme? This is really weird, because, from what ...
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1answer
56 views

FM and phase/frequency deviation

I have a small understanding issue here, so I would be very glad if someone could help me a bit! We are given this FM modulated signal to volts; ...
0
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2answers
281 views

Double Side-band Amplitude for Radio Transmission & Single Side-band Reduce Carrier for Point-to-point Transmission

What are the reasons which lead to the use of double side-band amplitude for radio transmission, and single side-band reduce carrier working for point to point transmission? Thank you for your help.