Questions tagged [baseband]

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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 ...
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2answers
34 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 ...
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1answer
66 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\...
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1answer
20 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(...
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1answer
78 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 ...
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1answer
16 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 ...
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1answer
128 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.
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3answers
157 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, ...
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1answer
343 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 ...
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1answer
934 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 ...
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1answer
251 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}...
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0answers
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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 ...
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1answer
817 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 ...
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1answer
242 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....
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2answers
293 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 ...
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1answer
507 views

IQ modulation: baseband to bandpass transformation

can someone explain me these doubts? it is a baseband signal representation. A- complex signal, R- real. If I multiply baseband signal with FT( cos) then the signal will look like this ( on the ...
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1answer
90 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?
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0answers
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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 ...
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2answers
455 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 ...
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1answer
407 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} \...
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3answers
974 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 ...
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1answer
2k views

Matlab : Adding noise with regard to signal-to-noise ratio or EbNo?

A signal x takes values from an alphabet set. My objective is to estimate the channel parameters hest using adaptive methods and ...
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1answer
1k 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 ...
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1answer
2k 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 ...
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1answer
1k 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 ...
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2answers
737 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 ...
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1answer
2k views

How to “draw” the function/wave to send symbols using QAM?

Say you have the following 8QAM constellation diagram: Say, you want to send the sequence: 001 110 101 000 001 How would you draw the function/wave containing the symbols? My problem in ...
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2answers
3k views

How to apply low-pass filter to an I/Q signal to get baseband signal?

Can anyone help me with the demodulation technique of a modulated signal? I mixed it with I/Q signal. But I am very confused about low-pass filtering. I am trying to apply a low-pass filter, but I am ...
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1answer
3k views

Baseband vs Bandpass Signal [closed]

I cannot find any reliable or reasonable differences between the two even after searching for it! Please tell me the possible differences with reasons and reference links!