# Tag Info

### How to "draw" the function/wave to send symbols using QAM?

The baseband QAM signal is complex, and the only way to draw it is by doing two drawings, one for the in-phase (real) component, and one for the quadrature (imaginary) component. The passband QAM ...
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### MATLAB: Adding Noise with Regard to Signal to Noise Ratio (SNR) or EbNo?

These stuffs $E_s/N_0, E_b/N_0 \textrm{ and SNR}$ are convertible. \begin{align} E_s/N_0 &= E_b/N_0 + 10\log_{10}(k) \\ E_s/N_0 &= 10\log_{10}(T_{sym}/T_{samp}) + \mathrm{SNR} \end{align} ...
• 6,595
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• 28.2k
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### why don't we use Broadband technology to transmit digital signals ,and use Baseband technology to transmit analog signals?

"Broadband technology" is not inherently coupled with "analog signal transmission", as "baseband technology" is not coupled with "digital signal transmission". ...
• 1,729
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### How to recover data/information from real complex baseband signal?

In an actual received signal you will also have to address the frequency, phase and time offsets between the transmitter and receiver since they run off of independent clocks that aren’t otherwise ...
• 51.4k
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### Digital Phase Modulation baseband or passband?

Assuming $g(t)$ is a baseband signal, $s_m(t)$ is passband. You can see that it is by multiplying the two complex exponentials, expanding the result into sine and cosine terms, and then taking the ...
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### Spectrum of a baseband digital signal

The spectral shape mainly hails from overlaying an f0- and f1-shifte sinc as formed by the upsampling filter – which is a boxcar filter in your case. So, basically, you're doing a bad version of ...
• 30.8k
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### The baseband sampling frequency when the negative spectrum is considered

As Hilmar points out in a comment, the answer depends on whether the baseband signal is real or complex. Consider a real baseband signal $r(t)$ with bandwidth $B$. It must be sampled at rate $2B$. ...
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### Why are all baseband signals low-pass?

If "low-pass" is defined as "does not modulate a carrier", then most signals in nature are low-pass -- asking "why" is a bit like asking why trees have roots: nature ...
• 15.3k
1 vote

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

"You simply can't..." - it isn't true. Let me explain by pictures... Base band signal with bandwith B: S(f) sampled with Fp > 2*B: S(f) sampled with Fp < 2*B: Analytic ...
• 123
1 vote

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

You simply can't. The analytic signal contains the exact same amount of information as the original real-valued signal, and if either is undersampled, you get the loss of information that ...
• 30.8k
1 vote
Accepted

### Frequency Support of Window Functions

A window function $w(t)$ satisfies $w(t)\ge 0$. The value of a window's frequency response $W(f)$ at DC ($f=0$) equals its integral $$W(0)=\int_{-\infty}^{\infty}w(t)dt>0\tag{1}$$ which is clearly ...
• 90k
1 vote

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

It means the same thing. The negative frequencies are there to cancel out the complex portion of the signal in the time domain, so that the time domain signal is constrained to the real axis. The ...
• 2,710
1 vote
Accepted

### Bandwidth computation for NRZ baseband transmission scheme

The first statement says that for the given binary sequence of $$a_k = \{ 1,0,1,0,1,0,...\}$$ the transmitted NRZ line-signal would oscillate at the maximum rate : $$V = \{+A,-A,+A,-A,...\}.$$ which ...
• 28.2k

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