Questions tagged [frequency-modulation]

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What is the frequency response function for an input through a differentiator and mixer?

Through the differentiator, the frequency response will be $j \omega X(j\omega)$, but what about through a mixer with $\sin(\omega_ct)?$ Will it be \frac{1}{2j} j\omega\left[X(j(\omega-\omega_c))-...
762 views

Combining 2 sinusoids of equal amplitude with different frequencies into 1 new “wave”

This question is about combining 2 sinusoids with frequencies $\omega_1$ and $\omega_2$ into 1 "wave shape", where the frequency linearly changes from $\omega_1$ to $\omega_2$, and where the wave ...
202 views

Recommendation for good ressources on digital processing and D-QPSK

I've been a C++ developer for 10 years. Quite high level. And I am completely new to Digital Signal Processing. I am trying to implement a Software Defined Radio. Specifically I am trying to receive ...
42 views

Noise floor of a FM duplex

If these 2 signals, that form this duplex, have ranges of 15-30 [kHz] and 30-45 [kHz] using: $NoiseFloor_{dBm} =10\log _{10}(k\times T_{0}\times 1000)+NF+10\log _{10}(BW)$ (formula from wikipedia) ...
284 views

Biquad cookbook formula for broadcast FM de-emphasis?

Can a simple IIR biquad filter be used as an audio de-emphasis filter for broadcast FM radio? If so, how does one translate the filter requirements (50 uS time constant in the U.S.?) into parameters ...
47 views

The link of the statement is evidenced in this book: I don't understand how equation 85 come? I try to use Carson rule to see this inequality but turns out I have $2 \Delta f$ instead of $3 \Delta f$....
5k views

FSK and IQ modulation

I am having trouble understanding the FSK modulation process. There are many ways of demodulating the FSK signal. What is the advantage of performing the FSK using IQ modulation? How to demodulate ...
2k views

Quadrature modulation for FM and AM

This might be a naïve question, are these correct statements? Both amplitude and frequency modulated radio signals nowadays use quadrature modulation and demodulation as a mean to transfer and ...
125 views

Receiving frequency modulated signal

I have two questions: If the FM radio at the receiver mixes with a another frequency to bring down the carrier frequency, wouldn't that affect the message signal? In today's digital world, why the ...
679 views

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 ...
341 views

Simplified equations for FM (frequency modulation) synthesis and PM (phase modulation)?

Clicking on the links I find on the web it seems many authors don't express them neatly enough for me or they're even confusing the two. Can someone please clear this up? Is frequency modulation \...
154 views

Simulation of a Frequency ramp

This might be an easy one! Please preface your answer with spoiler notation by typing the following two characters first ">!" Given the following equation that describes a cosine wave as a function ...
428 views

Solving for frequency deviation, $\Delta f$ (FM modulation)

I'm sorry if I posted this in the wrong section. I solved the question and got $50\textrm{kHz}$, but the solution says it is $100\textrm{kHz}$ without any proof. Im asking for someone to tell me ...