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Calculating PSNR using STFT of sampled signal

I have a baseband IQ sampled signal from a Pluto SDR with a bandwidth B and also fs = B, how can I calculate its PSNR using the STFT of the signal in Matlab. Do I need to take into account the RBW of ...
Daniel Cohen's user avatar
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1 answer
49 views

Why do I find a low frequency oscillation when I add a carrier frequency to my baseband signal ? And Why is my demodulation step not working?

I am trying to build a simulation for a 2PPM signal, modulate it at high frequency and then retrieve my baseband signal. Here is my full code (minus the plots) before explaining more. ...
Aloys Reant's user avatar
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1 answer
72 views

PSD of real and imaginary parts of complex envelope of a bandpass signal

I know that we can write a real bandpass signal x(t) as: $x(t)=x_c(t)\cos\omega_ct + x_s(t)\sin\omega_ct$ $x_c(t) = 2x(t)\cos\omega_ct$ for $|f|<W$ $x_s(t) = 2x(t)\sin\omega_ct$ for ...
Ang's user avatar
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1 answer
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Adding Narrowband Interference to Spread Spectrum Signal in MATLAB (Baseband Model)

I am interested in adding a narrowband interfering signal to my spread spectrum signal. In the waveform model, it's straightforward to generate a narrowband signal within the frequency range of the ...
Digi1's user avatar
  • 161
1 vote
3 answers
223 views

Why are all baseband signals low-pass?

A baseband signal is just a signal that has not been used to modify a carrier signal. Now, I have noticed that all baseband signals are low-pass too. Why is that? I can understand why digital baseband ...
tryingtobeastoic's user avatar
2 votes
1 answer
93 views

Is BPSK relevant, or does it even exist, in wireless data transmission?

I ask this question because it seems to me that if pulse shaping has been applied in the transmitter, the signal that is actually transmitted is not phase modulated at all, rather, it is amplitude ...
Drummy's user avatar
  • 133
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1 answer
578 views

How can I generate a OFDM baseband signal with the output of the ifft?

I have some understanding problems with OFDM. I think I have understood most of the theoretical concept. At the moment, I am trying to write some Python code to simulate the transmitter part. This is ...
Not A Hobbit's user avatar
1 vote
1 answer
90 views

The baseband sampling frequency when the negative spectrum is considered

Suppose I have a signal $x(t)$ of bandpass bandwidth of $2W$ Hz. The sampling frequency must be at least $2W$ in baseband, because the largest frequency component is $W$ Hz. I understand that, when we ...
Math_Novice's user avatar
0 votes
2 answers
171 views

Practical problems in down-converting via Hilbert filter

While teaching communication system to my students, I showed different ways to define the diagram block of the system responsible for transforming a bandpass signal, $x(t) \in \mathbb{R}$, into its ...
Rubem Pacelli's user avatar
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1 answer
82 views

Signal power after frequency shift with different frequency than the carrier frequency

I have this received signal in passband $$ \begin{split} r(t)=&\Re\left\{\tilde{x}_1(t)e^{j2\pi f_1t}+\tilde{x}_2(t)e^{j2\pi f_2t}\right\}\\ =&\Re\left\{e^{j2\pi f_1t}\underbrace{\left[\tilde{...
Math_Novice's user avatar
4 votes
1 answer
777 views

How is the maximum theoretical data rate of a channel equal to $2B\log_2(V)$ bits/sec.?

According to Andrew S. Tanenbaum (in "Computer Networks", Chap. 2, Section 4 "The Maximum Data Rate of a Channel"), the Nyquist/sampling theorem states that "if an arbitrary ...
j3141592653589793238's user avatar
1 vote
1 answer
386 views

Spectrum of a baseband digital signal

I'm building a Continuous-Phase BFSK Transmitter using Python and PlutoSDR. Something that I don't understand is the spectrum of the up-sampled baseband signal - the digital 0's and 1's over-sampled ...
BeeKayel's user avatar
1 vote
1 answer
165 views

Cut-off frequency for Low-pass filters in Arctangent Demodulation

According to literature, the arctan-demodulation method commonly used in Radio-frequency radar systems is the one shown below: Is there a rule of thumb regarding the cut-off frequency of these Low-...
Charis Hadjipanayi's user avatar
2 votes
2 answers
1k views

Why is Complex Baseband better than Real Representation?

I read that one of the advantages of a complex baseband signal is that it can send more data over the same bandwidth as compared to real signal. Why is that so? If I think about it logically, doesn't ...
John Smith's user avatar
1 vote
0 answers
702 views

SDR : IQ GMSK signal demodulation

I'm trying to develop an application for the demodulation of some GMSK signals transmitted over the air. I'm using a RTL-SDR which outputs 8 bits IQ samples of the baseband signal. Here is what I've ...
pior's user avatar
  • 11
1 vote
0 answers
218 views

Analytic Signal vs Baseband Signal

I am wondering if a baseband signal, which is can be defined as $s_{BB}(t) = I + jQ$, is at the same time an analytic signal. In my understanding, analytic signals are defined as $s^+(t) = s(t) + jH(s(...
Benjamin's user avatar
0 votes
2 answers
209 views

An Impulse in Complex Envelope (i.e. baseband) Notation?

In complex envelope notation, a modulated RF signal, say v(t), is represented in complex envelope notation as v(t) = Re{ g(t)e^(jwct)}, where wc is the carrier angular freq, g(t) = x(t) + jy(t), and g(...
Vince's user avatar
  • 11
1 vote
2 answers
170 views

Restore real signal from its complex representation if sampled under Nyquist frequency

Assume we have: real signal: $s(t)$ its analytic representation: $s^+(t) = s(t) + j*H(t)$, where $H(t)$ - Hilbert transform of $s(t)$ Spectrum of $s^+(t)$ has only positive part, so may be sampled ...
Andrew123's user avatar
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1 answer
180 views

How to recover data/information from real complex baseband signal?

I have recorded real complex baseband signal. I want to recover data from the same. The complex baseband signal is basically a composite CDMA signal. How can i recover that information ? Original Tx ...
Jay Patel's user avatar
  • 158
0 votes
1 answer
369 views

Is there an intuitive explanation for what complex basebanding a signal is?

I have an algorithm which takes an input signal, $x[t]$, and (among other things) complex basebands the data and outputs the phase of the complex numbers. I'm new to the field and the Matlab function ...
Dan Pollard's user avatar
0 votes
1 answer
82 views

How to add a frequency offset to a buffer of MPSK signal for simulation purposes?

I need to simulate some channel effect to a buffer of MPSK signal. How to add a frequency offset to a buffer of baseband MPSK signal?
Linda's user avatar
  • 49
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1 answer
172 views

Digital Phase Modulation baseband or passband?

Say I want to transmit messages using PSK: I send the message $$s_m(t) = \text{Re} \left [g(t) e^{\frac{j 2 \pi (m-1)}{M}}e^{j 2 \pi f_c t} \right]$$ where $f_c$ is the carrier frequency. Now my ...
DarkLink's user avatar
  • 307
1 vote
2 answers
98 views

Frequency Support of Window Functions

All window functions, which go from zero amplitude, up, then back to zero amplitude, are all base-band signals. Why is this? Are all functions that have this behavior always band-band aka low-pass?
The Dude's user avatar
  • 632
0 votes
2 answers
1k views

Complex Samples (IQ) - Baseband Filtering

We are currently analyzing a large set of IQ samples in a desktop application and we are interested in implementing many different bandpass filters dynamically. We realized, that working with scipy ...
Tiaro's user avatar
  • 3
0 votes
1 answer
211 views

why don't we use Broadband technology to transmit digital signals ,and use Baseband technology to transmit analog signals? [closed]

I learn the Broadband technology and baseband technology in this website: https://www.computernetworkingnotes.com/networking-tutorials/differences-between-baseband-and-broadband-explained.html ...
Shine Sun's user avatar
  • 159
0 votes
2 answers
269 views

Meaning of negative frequencies in Baseband non sinusoidal, non periodic signal

I can understand the meaning of negative frequencies in a sine or cosine signal, since by using Euler's identities, you have two complex phasors moving to different directions, which when added, give ...
NickG's user avatar
  • 121
4 votes
1 answer
3k views

Sample rates, Samples per Symbol, and Digital Pulse Shaping

Having some confusion about digital pulse shaping for complex baseband (passband) signals. The complex baseband linear modulation equation is $$s(t)=\sum_{m=-\infty}^{\infty}\text{Re}\{a_m\}h(t-mT)+j\...
user67081's user avatar
  • 723
-1 votes
1 answer
185 views

Having Problem about DownConversion

I hope, you are doing well. I want to ask question about baseband conversion. Background: I generated two AM signals in MATLAB, which one of them is shifted in time. I multiply the signals with $\cos(...
user avatar
1 vote
1 answer
2k views

Bandwidth computation for NRZ baseband transmission scheme

In Andrew Tanenbaum's book on Computer Networks, while explaining about bandwidth of a NRZ (Non Return to Zero) baseband transmission scheme, he says the following: With NRZ, the signal may cycle ...
pendingIntent's user avatar
0 votes
1 answer
110 views

Phase changes of BPSK modulated carrier after moving to baseband

Given a BPSK-modulated carrier what would happen to the phase changes in the signal after the carrier is moved to baseband? Would the time intervals between the phase transitions in the time domain ...
axk's user avatar
  • 237
1 vote
1 answer
266 views

Baseband signal processing algorithms [closed]

What is one exactly referring to when you say "baseband signal processing algorithms"? Can anyone give a few (common) examples.
Akshat's user avatar
  • 11
1 vote
3 answers
1k views

Why bit rate is same in a lower frequency spectrum and higher spectrum?

If there is a spectrum between 0 Mhz - 1 Mhz, bandwidth would be 1 Mhz here and for example with baseband we can send 2000 bps. What I can't understand is if spectrum is 5-6 Mhz instead of 0 - 1 Mhz, ...
Abdullah Akçam's user avatar
0 votes
1 answer
2k views

Baseband representation of a LFM chirp signal

I need to generate a chirp signal between $f_{start} = -f_{limit}$ and $f_{stop} = f_{limit}$, to compare it to a FrFT generated signal. The FrFT signal of order $\alpha = 0$ is PAM modulated data ...
DaDSPGuy's user avatar
  • 182
2 votes
1 answer
4k views

Nyquist Maximum data rate formula for PCM

The Nyquist maximum data rate formula for a binary PCM is given by $$C = 2B\log_2L$$ I'm not very sure what "$B$" is here. Is it the bandwidth of the signal being sampled or is it the channel ...
Navin's user avatar
  • 35
2 votes
1 answer
691 views

Relation between constellation SNR and baseband SNR

Let's say I have an I/Q modulation, ie. QPSK. I can simulate an the effects of an AWGN channel by adding to my QPSK symbols the realizations of a complex normal. $\mathcal{CN}(0,\frac{1}{\mathrm{SNR}...
xvan's user avatar
  • 23
0 votes
0 answers
105 views

Binary Polar vs 4-PAM Signalling

Why is binary polar signalling not feasible for a data rate of 2.0Mbps within a bandwidth not exceeding 1MHz? Is it due to the fact that binary signalling can only transfer 1 bit of data per symbol ...
Mikey's user avatar
  • 27
3 votes
1 answer
4k views

QPSK Data Rate vs Bandwidth at Passband: Why can it only transmit 1 bit per Hz and not 2 bits per Hz?

1) This is a follow up question to the most up-voted answer to this question. 2) The accepted answer is that "QPSK transmits 1 bit per Hz at passband". 3) The theory found in books seems to agree ...
EGL's user avatar
  • 33
0 votes
1 answer
1k views

Converting complex baseband signal to passband signal

I have to convert baseband signal (BW-20MHz) to passband signal centred at 20MHz. I am implementing this in matlab. so, this is how I tried it. I have already generated LTE Waveform BW- 20MHz , fs =30....
Hitman 47's user avatar
3 votes
2 answers
799 views

Why would we simulate baseband rather than passband

My question is, Why do we usually use baseband in simulation rather than passband? however, if we want to test our simulated idea in real environment, it must be sometimes in passband !! So, should ...
New_student's user avatar
1 vote
1 answer
1k views

IQ modulation: baseband to bandpass transformation

Given is a baseband signal representation. A : Complex Signal R : Real Signal If I multiply baseband signal with FT(cos) then the signal will look like first plot ...
LenaPark's user avatar
0 votes
1 answer
146 views

IQ modulation principle

I am new in the signal processing. I hope I can get help. I want to ask a question regarding IQ modulation work . Why can’t I simply multiply a complex base-band signal with a cosine to modulate it?
user176070's user avatar
1 vote
0 answers
24 views

Can you use the theory of Signal Space to study Band Base digital systems?

Introduction: There is one way to study different modulations in band pass digital systems and is working with "signal space" and the Constellation Diagram. My questions about this are: 1) Is it ...
WhiteGlove's user avatar
0 votes
2 answers
1k views

Bandpass filtering IQ samples from USRP

I have an USRP (B205mini) with an RX frequency of 900 MHz and a bandwidth of 100 MHz. I want to distinguish between two raw, unmodulated signals at respectively 875 and 925 MHz. My approach would be ...
mpetitjean's user avatar
0 votes
1 answer
574 views

QPSK on baseband question

Given a signal you are asked to perform baseband QPSK (not on a carrier). Does this mean the following? In baseband QPSK the (possible) constellation points are $$\sqrt {E_s} e^{jn \pi / 2} \...
bolzano's user avatar
  • 133
0 votes
3 answers
2k views

How can I generate offset QPSK symbols from QPSK symbols

I am trying to generate Offset-QPSK modulated symbols. But I am facing some difficulties. I know how to make QPSK symbols but I am unable to figure out at what stage I have to bring in changes to make ...
wanderer's user avatar
  • 151
1 vote
1 answer
3k views

MATLAB: Adding Noise with Regard to Signal to Noise Ratio (SNR) or EbNo?

A signal x takes values from an alphabet set. My objective is to estimate the channel parameters hest using adaptive methods and ...
Ria George's user avatar
5 votes
1 answer
3k views

How do I convert a real baseband signal to a complex baseband signal?

I have radio telescope observations that have resulted in two real-valued signals (corresponding to the right- and left-handed circular polarizations). The signals are sampled at rate $2B$, and ...
XYZT's user avatar
  • 351
0 votes
1 answer
3k views

Downconverting real signal to IQ baseband

Despite reading various answers on this site and on other sites I am still confused about how to convert a real-valued signal back down to its original IQ baseband values. Note I am still a beginner ...
user2562609's user avatar
1 vote
1 answer
3k views

Autocorrelation and Power Spectral Density (Discrete)

The Autocorrelation, $\phi_{aa}[\kappa]$, of a discrete time random process, $a[k]$, is defined as: $$ \phi_{aa}[\kappa] = \mathrm{E}\left\{ a[k+\kappa]a^*[k] \right\} $$ Taking its fourier ...
sundar's user avatar
  • 343
-1 votes
2 answers
1k views

Frequency spectrum of complex equivalent Baseband Signal - Frequency Content around carrier frequency

Basically my objective is to generate a complex equivalent baseband signal of an AM modulated wave in MATLAB. Then to view the difference in frequency spectrum of AM modulated RF signal vs complex ...
sundar's user avatar
  • 343