# Questions tagged [modulation]

Modulation is the process of varying one or more properties of a high-frequency periodic waveform, called the carrier signal, with the amplitude of low-frequence modulating signal which typically contains information to be transmitted.

86 questions with no upvoted or accepted answers
Filter by
Sorted by
Tagged with
197 views

### Up-converting a sinusoidal signal

I want to up-convert a baseband sinusoidal signal of frequency $4000 \, \rm{Hz}$ using a carrier frequency of $20\, \rm{KHz}$. I read that one can up-convert a baseband signal to a passband signal ...
90 views

### How to find the noise power in my simulation

I am currently working a tricky communication chain that I want to simulate into Matlab. The chain is like a classic BPSK modulator/demodulator chain, but where the BPSK modulated signal has been ...
198 views

### Multiply signal $x[k]$ with $\cos(2\pi\nu_0k)$, then given $X(\nu)$ draw resulting function in frequency domain?

Let $$y[k]=x[k]\cdot \cos(2\pi\nu_0k) .\tag{1}$$ Then, given a signal $x[k]$ with the DTFT $X(\nu)$ according to the following figure what will the frequency domain for $Y(\nu)$ look like for a ...
265 views

### How to calculate the accurate BER expression of circular 8-QAM constellation modulation?

It is easy to understand the BER derivation of square QAM, but the circular 8-QAM? I'm quite confused. The decision region is not in a rectangular shape anymore, meaning regular way does not work here....
96 views

### Does anyone recognize this modulation?

I'm trying to extract the code of my garage remote, but i have some difficulty to find witch modulation has been used. At first I thought it was a simple digital modulation, but there is some strange ...
850 views

### Information in GFSK signal

I was measuring a Bluetooth LE Signal, particullary a Channel with center frequency 2402 MHz and Bandwidth of 2 MHz, 2401 - 2403 MHz. Those measurement points are just the highest peaks. In the ...
459 views

### Demodulation distortion in single-sideband and double-sideband

I am trying to compare the demodulation for single sideband (SSB) and dual sideband modulation formats (DSB) when the reconstructed carrier is not perfect (i.e. shifted in both frequency and phase). I ...
223 views

### What is dynamic pulse-width modulation?

I'm working through exercises in a book called The Audio Programming Book and have been doing okay for nearly 300 pages, but have just got stuck. (I'm a musician, not programmer or audio specialist ...
140 views

### TDE, OFDE and FDE equalizer simplest exmple in matlab

I want to implement the equalizer in matlab. I am just learning this. I want a good kick start code that can help me to learn it further. I searched a lot on Google but do not find a good reference ...
1k views

### How to implement GMSK demodulation

I am currently trying to implement a GMSK demodulator, using Java. I am actualy trying to use the model of this block diagram. However, I really do not know what goes on within the mode selector and ...
5k views

### Adaptive Delta Modulation For Speech Signals

I need to implement an adaptive delta modulation encoder and decoder using matlab for my term project. How can I code a good adaptive delta modulation? How can I change ...
9k views

### Maximum Frequency deviation in Frequency Modulation

I am writing a script to frequency modulate the stereo audio signal, and later calculating the modulation index wrt time. As we have to modulate the stereo audio signal, I have to first synthesize ...
23 views

### If a function has slowly varying amplitude and phase what is the bandwidth of the amplitude and phase individually?

I am dealing with time histories that are narrow band with slowly varying amplitude and phase. I wish to extract the amplitude and phase but there is noise on the time history. An example of the type ...
37 views

### SNR measurement

I am using QPSK modulation for a BER of $10^{-6}$ at $\text{SNR}=E_b/N_0=10 \ \rm dB$. If my data rate is $5 \ \rm kbps$ then $$S/N_0 = 10\log_{10}(5000)+10 = 47\ \rm dB$$ And if my RF section has a ...
137 views

### Wideband FM bandwidth estimation

In the book Modern Digital and Analog Communication Systems by B. P Lathi, there is a section for the estimation of WBFM bandwidth. First, the staircase approximation of $m(t)$ is constructed by the ...
21 views

### How composite signal in CDMA is normalise in general?

I had CDMA composite signal with 3 users. I assume that the signals are linearly sum together so for my maximum and minimum amplitude of composite signal are +3 and -3 respectively. How can i ...
38 views

### Non-coherent FSK and Orthogonality and square-law detectors

This is a basic figure that explains how Non-Coherent FSK actually works. The incoming signal $r (t)=\sqrt{2 P}{Cos}(2 \pi t (\text{fc}+\text{fi})+\text{n(t)}$ where P denotes the signal power in ...
55 views

42 views

### Cosine modulated impulse response

How do we show $y_0(n) = y_1(n)$ when $h_k[n] = h[n] \cos(\frac{2\pi}{L} k n )$
120 views

### Coding an LFO in C

I want to know how I could implement a Low Frequency Oscilator on a simple synth I've coded in C. First in order to understand how to make this happen I would like just to modulate a sine wave by a ...
24 views

### modulation depth

When a value for the power dissipated by an AM signal is given, and the depth of modulation is also given. Then you are told to find the modulation depth required to increase the power to a higher ...