Modulation Definition and 145 Threads

Hi all I need to add GPS digital output (in form of Lat/Long) in an existing analog audio signal whose bandwidth is 100 Hz-20 KHz. This GPS data should be added in such a way that it should not interfere with audio signal neither total bandwidth of analog signal should exceed 40 KHz. This...

If a mass is moving it has a wavelength - my question is, is the gravitational field of the mass then modulated accordingly ?

I'm stuck on this because v is a 2 tone signal, so it's not as simple as Am/Ac. The teacher said I will need to differentiate it and equate it to zero, which I thought made sense. Differentiating v gives me: [- mwsin(wt) - mwsin(2w*t)], so there's still unknown variables. I don't know how I'm...

I'm trying to understand this paper and others on the same topic. I struggle conceptually with their first equation, which is an expression for an imperfectly phase modulated optical field from an electro-optic phase modulator (EOM) that is contaminated with a little bit of amplitude modulation...

Please Notice That the Toroid Coil is Outside the Discharge Tube and yet able to influence electrons moving inside the Tube.

I want to know the frequency domain spectrum of an exponential which is modulated with a sine function that is changing with time. The time-domain form is, s(t) = e^{j \frac{4\pi}{\lambda} \mu \frac{\sin(\Omega t)}{\Omega}} Here, \mu , \Omega and \lambda are constants. A quick...

Hi, I wanted to refresh some knowledge, some years ago @berkeman helped me out with this , thanks. 1) In an AM modulation a fixed frequency carrier wave is amplitude modulated , where the amplitude represents the lower frequency information signal, this modulation of a signal that is amplitude...

3) Suppose, V DSB-SC as follows: Are the following spectrums correct? The carrier frequencies are given as an example.

Question: For frequency shift key modulation in the binary case, how are the two carrier frequencies chosen? From online reading, I have seen that the carriers are chosen to be different but also with the goal of minimising bandwidth and without any overlaps of the spectra, etc. However, I...

Hello, I am after some help to try and understand SVM implementation is a micro that controls a motor. As I understand it one of the advantages of using space vector modulation over sinusoidal PWM modulation in motor control is that it can control the phase voltages such that the line-to-line...

1. Add impedance in parallel of capacitor and resistor Z_rc = 1/((-wC/j) + 1/R) = (jR)/(j-wRC) 2. Ohm's law for relationship of i_d, Z_rc, and Vo Vo = i_d * (jR)/(j-wRC) Unsure how to do the rest? Thanks.

Is the carrier wave modulated or in other words "modified" with the information signal? If so how exactly is this done? I can't find or maybe I am looking at the wrong things but I don't understand how this is done. I know that AM is modulated with the amplitude and FM is modulated by the...

Hi, I'm struggling to understand how channel length modulation takes place in mosfet. The books n internet said that as drain side is positive, there is less potential difference between positive gate and positive drain, while there is more potential difference between positive gate and zero...

Okay, so SPM (self-phase modulation) is an effect that happens when an ultrashort pulse travels through a medium and it leads to a change in that pulse's frequency spectrum. It is explained that it occurs because an ultrashort pulse somehow induces a varying change of refractive index and this...

I have a MATLAB script for modelling a two tone signal (a sum of two sinusoids) going through a non linear transfer function (such as an amplifier). The amplitude of a signal is amplified non linearly, and also the phase is modified depending on the input power of the signal. The two sinusoids...

visible light contains a range of frequencies i.e not of single frequency, then how visible light is used as a carrier in Visible light communication. Further more is it possible to modulate light (in tera HZ frequency range). what modulation scheme is possible and how it is implemented in VLC...

Homework Statement I am giving the following signal: and asked to get the DSB-SC signal of this Homework Equations 3. The Attempt at a Solution [/B] So, I know a few things. My prof writes that I would have to multiply my original signal out and then take the Fourier transforms...

Hello, There is a thing I struggle to understand on laser physics. There is a modulation method called direct modulation for semiconductor lasers where by changing the current we modulate the light which is emitted form the laser cavity. There is a picture below It is stated in...

Homework Statement The Attempt at a Solution What should the bandwidth be over here? Confused since there is no mention of carrier frequency.

Hi, I want to be able to vary the amount of capacitance in a circuit, ideally I'd like to be able to turn a knob to tap a bank of capacitors, something like the attached picture.Is there some sort of switching or device available that anyone can think of which does this? Cheers

not sure if this is dumb question but I was reading something about "beats" and saw some similarities with AM so I got to a conclusion if you have just two waves (same phase) with similar frequencies etc. sin(x)+sin(1.1x) you can maintain AM or...not? if not, why not? if yes than why do we need...

i just had my first Signals processing Lecture, during AM modulation part my prof said that: V_AM(t) = (V_main(t) + 1) * V_Carrier while V_Carrier = sin (omega * t) 1-is there a proof that we get the envelop of a function by adding one then multiplying by some trig value? 2- what's the...

What are some effective ways to convert a Pulse Width Modulation from a Microcontroller to a DC Voltage as a function of Pulse Width? 1. Use a low pass filter to remove the unwanted harmonics and leave only the 0th term of the Fourier Series. What produces a better DC Voltage an Active or a...

Hello everybody, I'm a little bit confused about two types of amplitude modulation. We distinguish here: Case I : Amplitude Modulation with suppressed carrier (https://en.wikipedia.org/wiki/Double-sideband_suppressed-carrier_transmission): Case II : Amplitude modulation with carrier: Now...

Homework Statement [/B] A pure tone (sine) carrier signal of 440 Hz is frequency modulated by another sine wave of frequency 440Hz with an amplitude of 1760. (a) For the steady-state portion of the output signal generated by synthesis above, calculate: i) the deviation and ii) the Index of...

1) I am studying modulation of carrier waves, but I still can't understand something: knowing that in AM the carrier wave has only one frequency and just only its amplitudes vary according to variations in modulating signal amplitudes, why AM carrier waves have bandwidth if the frequency is...

1) I understood how variations in the amplitude of modulating signals are represented in the carrier wave, but I didn't get how frequency variations of the modulating signal are represented, as both AM and FM modulations seem do not care about it. Ex: How to distinguish a high vocal range (high...

Homework Statement Let's say we have a carrier signal xc(t) = AcCos(ωct) And there is a modulating signal or we can call it the information signal xm(t) = Am Cos(ωmt) and the modulation index is given as 0.8 How to write the modulated signal? It's really confusing as many people give different...

Hello everyone. I have been practicing for my exam in fiber optics, and stumbled upon the following question: We have a transmission system with 3 channels, composed of a single mode fiber and a dispersion compensation fiber. Specifications are given for each. We need to calculate the channel's...

I have a few questions about AM, FM and PM. 1. If FM (or PM) radio modifies the frequency of the signal, how is the signal picked up without having to change the frequency constantly? 2. If PM modulates phase, which modulates frequency, what is the difference between PM and FM? 3. Why is AM...

rude man submitted a new PF Insights post Modulation vs. Beating Confusion Continue reading the Original PF Insights Post.

Homework Statement Hello, the plot in the image shows a modulated signal s(t), with one period of the modulating signal m(t). The mean value of m(t) is equal to zero . Its asked me to find the modulated index, the amplitude of the carrier, the equation of the message(m(t)) and the kind of...

" A intelligence signal is amplified by a 80% efficient amplifier before being combined with a 12kW carrier to generate the AM signal. if it is desired to operate at 100% modulation, what is the DC input power at the modulator" The choices are a: 12kW b. 7.14kW c.7.5kW d. 15kW my solution...

Hey guys, quick question. Is the modulation scheme described here (Armstrong's Phase Modulation) simply wide band FM? This Wikipedia article lists the following patent for Ed Armstrong for "Armstrong's Phase Method" and "Wideband FM" 1933 Patent: http://www.google.com/patents/US1941068

Homework Statement 2. Homework Equations The Attempt at a Solution I can't figure out how to get those numbers, I think I have to convert from dB when actually calculating it but I'm unable to get those ones. I have PQPSK = 0.502368 P16QAM = 0.0526855 P64QAM = 0.000004 Pno = 0.4450

Please look at the attachments below. I shall use the word "modulation" instead of "amplitude modulation" since I've been taught about AM only. So, my question is, in the first image (that I've attached), the messenger wave (which is modulated with the high frequency carrier wave) as well as...

Homework Statement I am utterly confused. When I was reading my textbook , I found something unacceptable. While deriving an expression for a modulated wave, It's been given that "A sinusoidal carrier wave can be represented as c (t) = Ac sin (ωt + Φ) where c (t) is the signal strength of...

I read that for VLC, they use toggling the LEDs ON/OFF to represent binaries. Why cannot we modulate the visible light like radio waves.

Hello, If been for a while trying to find information about how Doppler effect affects modulated signals. When a transmitter is moving relative to a receiver, the receiver will have a shift in the carrier frequency that will vary as the transmitter gets closer or moves away from the...

Hi all, I'm reading a paper on light sheet microscopy, i won't go into detail here but they are generating the light sheet by use of an Airy beam. They are using a term i don't understand when describing how the airy beam is generated. Quote "An Airy beam can be generated through the Fourier...

In Sedra&Smith's microelectronic circuits they have the following expression for the drain current in a MOSFET in saturation iD = 1/2µpCox(W/L)Vov2(1+VDS/VA)But I don't see how this can be correct. Wikipedia also has another expression, see...

when two sub atomic particles collide, being waves as well as particles. at point of collision do they act like radio waves and modulate each other. Are the resultant particle/waves produced by collision equivalent to upper and lower sidebands (as in AM modulation) or bessel functions (as in FM...

Homework Statement how the overall power becomes lesser when one side band is taken away by the bandpass filter and also how it limits the bandwidth of the signal Homework Equations The Attempt at a Solution there is will be the trade off between power and bandwidth. Vdc and Vm...

My understanding of the FM capture effect is that if an FM receiver receives two, on frequency signals, it suppresses the weaker one and demodulates the stronger one, given that the difference in signal strength is significant enough. This differs from the case of AM where the two signals are...

amplitude modulation -- why is ωc >> ωm necessary? i just want to ask why is ωc >> ωm is necessary for a good amplitude modulation

Homework Statement Why do we need Fp>>fs for a good modulation, where Fp is the frequency of the Carrier signal and fs the frequency of the originalsignal The Attempt at a Solution If we had Fp≤ fs or less there is no use of modulation, we need a big frequency so waves can go long...

What is a typical carrier frequency for amplitude modulation? In particular, for amplitude modulation in spectroscopy.

Phase modulation is a system in which the amplitude of the modulated carrier is kept constant, while its phase and rate of phase change are varied by the modulating signal. By the definition of phase modulation, the amount by which the carrier phase is varied from its unmodulated value, called...

AM amplitude modulation--- Hi everyone, I am learning AM recently, but I have some question that keep troubling me.. 1. We know that AM wave is produced by the multiplication of carrier wave and modulation wave. But why does the equation of AM wave is not a direct multiplication of Vm×Vc...

Hey guys. I have been theoretically playing around with a single phase full bridge inverter. What I wanted to do was determine the waveforms for the current going through each of the components (ie. the four diodes and the four thyristors). I assumed all of them were ideal. Since I have no idea...