# Questions tagged [frequency-modulation]

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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 ...
76 views

### Fractional Frequency Shifting a Discrete Signal in the Frequency Domain

In our current hardware-based signal processing pipeline, we have a time-domain signal $x[n]$ that we want to frequency shift by $f_0$. To do this, we multiply the signal by a complex exponential in ...
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I am trying to demodulate an IQ file containing a sample of a FM radio signal using two methods. First, I tried reading the whole file and demodulate all data at the same time. Second, I tried ...
1 vote
32 views

### Power of signal in specific frequency in FM and AM modulation

My professor gave us the following problem: Given a sinusoidal signal with $f_m = 1KHz$ which is put into an AM and FM modulation find the modulation index of FM and AM if you know that (amongst ...
1 vote
64 views

### What is the difference between sending pulses and modulating waves?

If you look for amplitude, frequency, phase modulation, you typically get some picture saying you have a wave and you modulate the corresponding parameter (amplitude, frequency, phase). On the other ...
762 views

### I'm missing something when it comes to understanding FM

I understand why FM is preferred for music: noise is mostly amplitude modulated, FM yields much higher fidelity. I also understand why commercial FM signals have a much larger bandwidth than ...
55 views

### Using SSB modulation to frequnecy shift an arbitary signal downwards

I've managed to use SSB digitally to create frequency envelopes such that I can increase frequencies at any arbitrary rate given by my envelop. But I am unable to manage a downward frequency shift. ...
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1 vote
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### I am working on chirp signal generation using DDS in verilog . To generate the chirp signal do I need to change the limit of the 8 bit counter?

I want to generate linear frequency modulated (LFM) waveform or a chirp signal using DDS in verilog. I am not using DDS IP Core. I have created DDS module using 8-bit rate counter, a 12-bit address ...
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1 vote
60 views

### Can someone help me with chirp signal generation using direct digital synthesizer(DDS) in verilog?

I want to generate linear frequency modulated (LFM) waveform or a chirp signal using DDS in verilog. I am not using DDS IP Core. I have created DDS module using 8-bit rate counter, a 12-bit address ...
• 23
75 views

### How is IQ-modulation done on the digital side rather than the analog side?

The original way of doing In-phase Quadrature (IQ) modulation is by modulating and mixing on the analog side. I have read that as the digital processing have gotten better, the modulation and mixing ...
120 views

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### Doubt in Frequency Modulation code

While searching for something FM, I came across this code. I am not able to understand a particular line of code. I have written a comment against that line of code. ...
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### Frequency modulation in MATLAB

I am trying to frequency modulate a cosine signal(for assignment). I have written the following code but not getting the required output. ...
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1 vote
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### FM: Do rational ratios of carrier to modulator signals really produce harmonic spectra?

I've read that in FM, all rational ratios of the carrier frequency to the modulator frequency produce harmonic spectrum in the FM signal. Link to what I read. I don't understand why this is. If for ...
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1 vote
231 views

### Frequency response of FM modulation/demodulation chain with phase derivative demodulation

Frequency modulating a carrier by white noise and then demodulating the complex signal using discrete derivative of phase it appears that the discriminator is acting as a low-pass filter. How do I ...
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I've been reading about FM and I keep coming to an expression, where the instantaneous phase $$\Theta=2\pi f_it+\phi\text, \tag1$$ where $$f_i=f_c+k_fm(t)\text,\tag2$$ ($f_c$ being the base carrier ...