Signal Definition and 935 Threads

I have a couple of questions about the theory about how to tell whether a system is casual and FIR or IIR. First point is about a casual system. Is it true that all FIR systems are casual? How can you tell if an IIR system is casual? I am I correct in thinking that a FIR system only has a...

I recently acquired an older Wavetek 2500 signal generator (.4 - 1100 MHz) and HP 54100A 1 GHz Digitizing scope for a project and am having a difficult time in getting an accurate voltage reading using anything other than a direct-connect BNC cable, and even that seems to have it's issues...

Let's say I lived in a big house, and in my big house I had a wifi connection that was fairly weak. So weak, that inside of my room I would only receive one bar of signal. How would I design a circuit that would catch the wifi signal, amplify that signal, and rebroadcast it inside of my room...

I would like to build an antenna that will be used in a very remote area to improve our cell signals. We have access to the GSM 850 (824.2 - 849.0 Uplink | 869.2 - 894.0 Downlink). I need help in calculating the antenna length based on the frequency and need advice on the most effective...

A) Let us say that we have some arbitrary sequence of natural numbers. e.g. 1, 2, 7, 3, 17, 19. Is it possible to convert every finite and infinite sequence into some continuous function model, such as in Fourier theory? I know that it is possible to extract some discrete samples from a...

Hello, I have the following Fourier complex signal: v(t) = 2/πsin(500πt)+1/2sin(1000πt)+1/3sin(1500πt) I need to find the minimum sampling rate for this signal. So, according to the Nyquist Theorem, the sampling rate must be twice the highest frequency component contained in the original...

One of the major concerns in any Cosmic Microwave Background (CMB) anisotropy analysis is to determine which fraction of the observed signal is due to some foreground contaminant. Two sources of foreground contamination have been firmly identified: the diffuse Galactic emission and unresolved...

consider two circuits: In circuit A the signal form mic AC (very low amplitude ) is combined with Vbb(to drive the BJT), as the two voltage sources are series they adds up and its amplitude increases and it is passed to bjt and then to loudspeaker. in circuit B the signal form mic AC (very low...

Hi, I have a complex time signal x(t)=X1*exp(i*∅)+X2*exp(i*2*∅). On converting to frequency domain, i expect frequency components at ω and twice of ω (when ∅=ω*t). FFT gives the desired frequencies, but the amplitudes don't correspond to X1 and X2. I understand that this is due to the phase...

Homework Statement how can i transmit ac signal to μC to further ADC? Homework Equations The Attempt at a Solution can i use dc offset?

Hi all, I am a longtime enthusiast for SETI and believer in extra-terrestrial life and intelligence. I became fascinated by it when I saw "Cosmos" by the late great Carl Sagan. The universe is a HUGE place. There must be many more lifeforms on other worlds out there. There are more galaxies than...

I have a discussion about shielding of noise generated by appliance and florescent lights. I know both Al and Cu are not magnetic material. BUT all noise are time varying meaning it is EM field. Good conductor block E field as loss is very high. How does that work when only the B field can pass...

Hello every1 .. i am sophomore so excuse me if i ask anything stupid/obviouse. so there are allot of proximity devices but with short range so i was thinking of making one with 2.4Ghz ℝℂ tx & rx. these typicaly have range to about 1km. So all i want to know is if there is a way to connect...

Two Questions: 1. I am new to electrical engineering but I want to know how I would Invert a signal. By this I mean, how do I turn a weak signal from, let's say a walkie-talkie, and turn that "weakening" signal into a "strengthening" signal. I would like for the signals to be inverted, in...

I have re-written this as as I accidently deleted my original post. I was wondering if the relativistic Doppler shift of a reflection from a mirror moving away from the observer was the same as the Newtonian equation in the special case that the mirror is orthogonal to the direction of motion...

Homework Statement I have a 13.56MHz signal to be used in a power sensor. However, in order for it to go through the RF/IF Phase and Gain Detector [AD8302], I need to shift the phase of this 13.56MHz signal by +90 degrees. I want to avoid using Transistors, due to the variation in β of...

Hey all: I have an audio signal from an old portable CD player that on max volume outputs about 1-1.2V as shown when attached an oscilloscope. I want to feed this signal into a PIC microcontroller, but I hear you need to amplify and shift the signal into the 0V to +5V region for it to work...

Hello, I have voltage signal that is time gated up to ns. I want to integrate this signal over this time interval, how one can do this and which device can be used for that. Regards MAAP

Catching up on the Universe Today I came across this article discussing the history of the wow signal. Since it fit the profile of a non-naturally generated signal, the would indicate either an equipment glitch or there really was something out there sending a signal. My question is, based on...

Hello I'm designing a project and i need a sensor that can detect human motion.I would like to detect the output signal of this sensor by searching it via laptop or mobile phone as if they are searching for a wifi signal. I would like to know if such sensor is available or should i build a...

I have a bunch of photodiodes and I want to interface to these to a computer using my sound card. I have 12 sensors and stereo input samples at around 96000hz. My idea is to connect 12 sensors to each line and have them turn on or off at a specified offset so that the total output signal would...

Hi all, i have heard a lot of signal deterioration. so i just wanted to understand if i send a pulse let us say of some 5V and measure it using an oscilloscope and send it through a very lengthy cable and measure the same signal with an oscilloscope can i find that the amplitude of the signal...

Hello all! First post! I've built a 7.83 Hertz sine wave oscillator that is fed into a 1,000 wind coil (soft iron rod/bifilar windings/self cancelling) and have tested in out on my oscilliscope and it's working beautifully with a peak voltage of 5.8 VAC (4.1 RMS AC). This device is being...

Hi, i would like to make an android app and a gps transmitter. Where do i start? (Sorry if this is in the wrong section)

The voltage is large AC signal, not small AC. I never deal with this kind of biasing... I am doing some simulations to extract the impedance of the device. I heard about some ways to measure it, like load pull, S parameter. But I can't not do measurement now... The device is quit...

Im not an elctrical engineer but I do need a source for the above mentioned switch. I would even be open to a simple schematic. Please Help.

How to read a signal through the sound card? I want to capture an amplified electric signal that emerge in the heart, and then to draw the ECG diagram. Can I use the soundcard's jacks for this purpose? if then, what is the best method to use to capture these signals using C++ on windows...

Hello, this time it's hard to tell whether this is the right forum to post this thread. Suppose I have a continuous function f:\mathbb{R}\rightarrow [0,100), whose Fourier transform exists and is known. Note that the codomain of the function is composed by all the real numbers between 0 and...

I've designed both types of filters for years and can't really explain the difference in clear simple terms. I'm hoping somebody here can help me out with that. First, some working terminology: RF filter - a filter with a controlled input and output impedance, usually 50 ohms, to match the...

I'm a beginner at electronics, so please bear with me... I have a 3V signal that is triggered under a certain condition and stays on for less than a second (I have no control over this). This is connected to a DAQ that can only sample at very slow rates (Also, no control over this). I'm...

How to find the period of two signals added for example: if f= s1+s2 where s1 is a squre wave of (+ -) 1 A, period √6 secs and s2 is a square wave of (+ -) 1 A, period 1/√6 secs. Is this signal periodic if not why? Can anyone let me know about some link where I can learn all the examples...

Is there any recommended books for signal processing for self study? Or like a reference book covering most fields? my final bachelor year has been filled with prescribed papers but I'm thinking I will need to be familiar with signal processing. At the moment I am looking "Digital Signal...

I'm new to the field of signal processing and currently reading a paper which it uses cross-correlation of two signals for detecting some machine failures. But I'm confused with the complex conjugate in the equations. Take equation from wikipedia as example: (f\star g)(t)\equiv \int_{-\infty...

Hi, Does anyone have idea on how to determine signal frequency? I am a first year graduate student in biomedicine and previously studied some general engineering, not really very versed in mathematics. We have lots of data measured from human to analysis, including EEG, heart pulse and...

Hey, I'm an EE undergrad looking to tentatively specialize in signal processing. My relevant background includes a course in signals/systems, introductory feedback control (using Nise), analog communication systems (using Haykin), introductory probability, the usual Calc I-IV sequence, linear...

So this is a very simple question that I am having some trouble figuring out: Let s(t) be a finite energy signal with Fourier Transform S(w). Show that \lim_{w \to \infty } S(w) = 0 We know by defintion that the FT of this signal is \ints(t)e^{-jwt}dt and also that ∫|s(t)|2dt < ∞. I'm a...

Video Monitor Jack repair I have a Fahrenheit 7” LCD Wide Color Vision monitor that has a broken jack. From the monitor is only this female connector: Then there is a cable that goes from 8 pins to 24 pins (I count 12 on each half?): Next after that cable is the box, where the...

Homework Statement Given the following block diagram. Calculate the transfer function H(z) and find \theta (f=\frac{f_{s}}{6}) Homework Equations H(z)=\frac{Y(z)}{X(z)} The Attempt at a Solution Ok So I know i need to find my y(k) output equation from this. I can then rearange the...

Homework Statement You have two clock signals (one is 25/sec,other is 30/sec). Design a circuit that takes both clocks as inputs, determines the faster one within a second, and indicates faster one by lighting an led. The led should remain on until reset by a control signal. You may use...

In the digital communication class I took, people talk about how to do detection and processing at the baseband. But from what I read, it seems that many systems do the signal processing at some intermediate frequency without mixing it all the way back to baseband. My questions are why and how...

Hey guys, I got this problem. I have 9 fans motors in which i need to send a range of dc signal of 0-10 volts to each one. I had decided to buy a simple signal generator that can do the trick but soon realized that having one signal generator hook up to 9 motors at the same time will not be...

If someone in a distant stars is watching for signals of life coming from other planets, how far did the signal of life in Earth travel yet, in a cosmological context?

Hi, I have to detect overvoltage on each of the 3 phases (individually) of a 3 phase AC signal. The 3 phase AC source has a neutral that is grounded and I have to use the same ground plane for my PCB. I was thinking of using a full bridge rectifier for each of the 3 phase but the problem is...

Can someone explain the steps of this solution? In my linear systems class, we are doing Laplace transforms using transform tables and the properties. I can usually do the problems that closely resemble the table, but when they involve heavy algebraic manipulations, I don't know what to do...

Hi all; I am trying to amplify a dc signal using the AD524 amplifier . I connected the input- pin (pin 1) to the ground. pin 2(input+) to 0.5V (The 0.5 came from a varibale resistor). pin 3 (RG2) was connected to G=10 (pin 13). Ref.(pin 6) was connected to ground. Pin 7 (VS+) 9V. pin 8...

Hi There are several posts here on group velocity, phase velocity and the confusion caused by it. I also read that article posted on mathpages.com (who is the author ?). I have some questions after reading these things. Like that article says, there three kinds of 'speeds' concerning...

Homework Statement Observing a star with a telescope where a photomultiplier is applied, 5 photons per second are detected on the average. Assuming a Poissonian statistics and the the background is negligible, determine the integration time useful to measure the flux with a standard...

Hello, I'm not an electrical engineering student so please bare with me... anyways if let's say you swallow a pill containing a piezoelectric sensor to measure adsorption of a molecule in the stomach how can you detect the changes in frequency? if there is no "physical" electrical connections...

Hi, Is there any method(circuit) to retain only the positive frequency components of a signal? thanks in advance.

What method is usually used to locate exact place of radio signal source? Do exist some type of radio signals, exact place of origin which is completely impossible to locate?Well,at least up to few hundreds of feets?