Questions tagged [frequency-modulation]
146 questions
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Fourier transform of frequency division
I need a mathematical description of what happens to the spectrum of a signal when that signal is processed to divide its frequency.
As an example, construct an input signal as the sum of two sine waves of different frequencies (as commonly used in…
Brian K1LI
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1
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1 answer
Convert old computer cassette signal into binary
Completely new to this but keen to learn :)
I have an old BBC Micro computer cassette which I've recorded into unsigned 8-bit pcm wav file format. The file comprises tracks separated by virtual silence and each track is split into a series of blocks…
Mark Mills
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1
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1 answer
Frequency modulation implementation without trig functions
https://dsp.stackexchange.com/a/1087 This answer suggests generating a sine wave using complex phasor multiplication. At each step the phasor is multiplied by another complex number (omega) to rotate it by the desired step. Then the imaginary part…
Jay Anderson
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Angle harmonic distortion in FM modulation
As you know the output form of FM modulator is something like this:
$$s(t)=A_{C}\cos(2\pi F_{c}t+\beta \sin(2\pi F_{m}t))$$
where $\beta$ is the phase deviation. I want to know why in this book the write has mentioned that narrow-Band FM modulation…
John Jin
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How to express FM and PM the most simple way?
I'm trying to understand how to tell phase modulation from frequency modulation by looking at their respective expressions, simplified, particularly frequency modulation. Also, it would be nice for someone to illustrate mathematically the difference…
user23148
0
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1 answer
What is wrong with this FM synth implementation?
I'm trying to get an FM synth to work, the synth uses wavetable oscillators, I am adapting the formula for FM synthesis:
$$
FM(t) = A \sin(\omega t + B \sin(\omega_m t))dt
$$
To use wavetable oscillators as carrier and modulator, so I am doing…
TiagoLr
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Does frequency modulation by direct method cause any phase modulation?
Phase modulation causes instantaneous frequency to vary according to modulating signal.
In the same way does Frequency modulation by direct method causes any phase variation in proportion to modulating signal?
sudheer
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I can't understand why there is a phase shift in phase modulation of a sawtooth wave
This is regarding question 5.1-2 (see picture attached) from Modern digital and analog communications, Lathi & Zhi Ding (2010).
I do not understand what the behavior should be at the discontinuity (sudden jump from 1 to -1). I ran the following…
Abeer
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How to calculate the frequency of the analog information signal? [FM]
How to calculate the frequency of the information signal from the follow spectrum diagram (it contains only one frequency)? Information signal is also called as original signal but i'm not sure.
ss221
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How to generate WBFM from NBFM?
An FM signal is given by
$$ s_{FM}(t) = A_c \cos [\omega_C t +k_f \int _{-\infty}^t m(\alpha)d \alpha] $$
Let $ \int _{-\infty}^t m(\alpha)d \alpha] = a(t) $
Therefore, $ s_{FM}(t) = A_c \cos [\omega_C t +k_fa(t)]$
Now, for NBFM, $k_f$ is very…
Soumee
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Can I alter audio recording frequency without altering the way it sounds?
Is there a way to increase frequency of an audio, for example (OK GOOGLE) recording of someone to inaudible range without change the way how it sounds? i.e >20000 KHz or <20 Hz.
A simple increase in frequency is resulting in increase of pitch.
Prometheus
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1 answer
Better way for fine-tuning to FM signal
I'm looking at fine tuning the frequency to a known FM broadcast automatically. (from complex signal) My beginner's idea is to either:
lowpass filter to get ~2x the bandwidth visible
do the frequency demod
get a moving average
apply frequency…
viraptor
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How to generate WBFM from NBFM
A narrowband FM is approximately given by:
$ x(t)= A[\cos w_ct - k_f a(t)\sin w_ct] $
where
$ a(t)= \int _{ -\infty } ^t m(\alpha) d\alpha$
How does frequency multiplying $x(t)$ by a desired multiplier result in WBFM?
Please show the mathematical…
Anwesa Roy
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