Generic term for coding information onto a carrier signal.
Questions tagged [modulation]
512 questions
13
votes
5 answers
Why is amplitude-modulated radio broadcast (AM) still active?
In my country (Germany) we have frequency-modulated (FM) and amplitude-modulated (AM) radio broadcasts. However, the reality is that no one ever listens to the AM since you just don't hear anything (I don't need to explain to you the downsides of…
OddDev
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How does frequency modulation takes place?
It is said that in frequency modulation the normal wave represents a '0' (False) and a more frequent wave represents a '1' (True).
Is there any particular rule that the normal wave's frequency should continuously be the same? How actually is this…
user1799
4
votes
2 answers
Is DC modulated with a sine wave actually AC?
So we have a DC level that, for example, varies between 0VDC and 10VDC in sinusoidal fashion. Is that classified as alternating current even though it does not go negative?
Dirk Bruere
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3
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3 answers
Is a triangle waveform a type of pulse width modulation?
I'm confused as I have seen a triangle waveform referred to in terms of PWM but a triangle waveform does not actually modulate the pulse width.
Is a triangle waveform a type of pulse width modulation?
SeanJ
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3
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5 answers
Why do sidebands appear after Amplitude Modulation?
In amplitude modulation, the amplitude of the carrier wave is changed according to the variations in the message signal, and that's what we draw inside the two envelops of the message signal, that's totally fine, but what is confusing to me, that we…
Sarthak Sharma
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2
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2 answers
Doubt in Amplitude Modulation
I am doing a course in Communication Engineering and on reading Amplitude Modulation in my textbook I found that a typical AM is defined by the following equation;
$$ s(t) = (1+k_{a}m(t))A_{m}cos(\omega t) $$
The reasoning which the book gives is…
Himanshu Sharma
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2
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2 answers
Does this look like amplitude modulation?
I have designed a transmitter and a receiver for amplitude modulation. Does the signal in the image looks like amplitude modulation?
el duderino
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2
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1 answer
Definition of \$\mu\$
I have a question as follows. This is not a homework question I just need to clarify my doubt on how this modulation index is defined.
Suppose a 2kHz audio tone having 2V amplitude is to be amplitude modulated on a carrier \$x_c(t) = 5\cos(6\pi…
Padmal
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Why is the modulating shape appear in both sides of the carrier signal in AM?
It's about Amplitude Modulation. Can anyone tell me why is this signal wave or modulating waveform shape appears in both sides of the carrier sine wave? Why not in one side only?
$$x_c(t) = A_c[1 + \mu x_m(t)]\cos(\omega_ct)$$
I copied this image…
Padmal
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1
vote
1 answer
QAM Modulation - destructive addition?
Doesn't symbols in QAM modulation add destructively as they are symmetric about the origin (equal amplitude and opposite phase) about the I axis?
Ananth Tenappan
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Tradeoffs between QPSK and BPSK re. spectral efficiency, error rate, etc
Say I'm using binary phase-shift keying (BPSK) to transmit some data at some rate. Now say that I want to double the data rate, without increasing my transmitter power. I could either continue to use BPSK but double the rate, or I could send two…
Phil Frost
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Amplitude Modulation Frequency
In am receivers, we detect the modulating signal by using envelope detector. So, the diode rectifies the signal, and the detected signal has doubled frequency than the original. Does this mean we will hear distorted sounds, if we connect audio…
TheDorkSide
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1
vote
1 answer
How to demodulate an overmodulated signal?
Say I have an overmodulated signal like the example above. When you demodulate this you will get distortion. Is it possible to somehow demodulate this?
codedude
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Delta Sigma modulation proof of average
It can easily be proven that an ideal analogue delta sigma modulator shapes the quantisation noise, as explained for example in this AD note under EQ 3: https://www.analog.com/media/en/training-seminars/tutorials/MT-022.pdf
Is there a similar…
PalimPalim
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Find the total amount of frequency multiplication needed for an Armstrong indirect FM modulator, when frequency deviation is adjustable in a range
I am currently practicing for my college exams and in this question, they are asking us to find the total multiplication needed in the system. But I am stuck because I have no idea of how to make use of this when both frequency deviation and…
leahnanno
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