# Questions tagged [digital-communications]

Digital Communication is the physical transfer of data (a digital bit stream) over a point-to-point or point-to-multipoint communication channel.

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### Isn't Gardner's algorithm and Early-Late gate the same thing?

I'm reading about some symbol synchronization methods and I find these two (ELG and Gardner) very similar. Early-Late gate takes 2 samples, one at $t=T-\delta$ and the other at $t=T+\delta$, then ...
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### Will the received waves be the same if the transmitter use the beamforming to transmit the same signal?

If there is a transmitter with three transmitted antennas,and a receiver with five antennas,and these five antennas are very close to each others. Now transmitter use beamforming with these three ...
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### What is the advantage of multiple antenna in receiver in energy harvesting ?harvested more power?

What is the advantage of multiple antenna in receiver in energy harvesting ? Assume there are $3$ transmitted antennas in the A device,and $1$ received antenna in the B device,now assume A device use ...
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### Doubts about Huffman and Shannon - Fano Coding

I was reading these slides about Source Coding and I have the following questions: 1) Let's consider this part: Can you explain me step by step the reasons of a, b, c? Which is the general rule to ...
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### To determine the Baud rate (in symbols/s) and throughput (in bits/s) of the system

You need to design a data transmission system where the data symbols come from an alphabet A with cardinality 32; all symbols are equiprobable. The bandwidth constraint is Fmin=250 MHz, Fmax=500 MHz. ...
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### Assumption of SINR measurement

I am assuming there is an Access Point (AP) and IoT Nodes in NOMA uplink scenario. Following is assumed: the AP does not know the channel gain of IoT Nodes the transmission power of nodes is also ...
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### Relation between frequency and phase in PLL?

Apparently both frequency and phase are independent properties but what is the relation between frequency and phase in PLL?so that when one is locked ,other is also locked
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### Best way to represent the result of the simplification algorithm

I need to represent a result of my algorithm and show that with this algorithm a calculation is simplified. I am going to plot a figure with 3 variables: The first one, on Y-axis I will show an ...
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### energy for a sum [closed]

I have $2$ signals $s(t)$ and $g(t)$ with different power. This is my question: To do the sum $r(t)=s(t)+g(t)$, should the $2$ signals have the same power? I would like an answer with justification.
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### Output of Zero-forcing equalizer doesn't match theoretical calculations

Let's say I have a sequence $x[n]$ (signal) and perform convolution with another sequence $h[n]$ (channel), so: $$y[n] = h[n]*x[n] = \sum_{k}{h[k]x[n-k]} \leftrightarrow Y(z) = H(z)X(z)$$ I'm ...
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### Why can we know the best precoding direction after we do the SVD to the channel?

Why can we know the best precoding direction after we do the SVD to the channel?for example $\mathbf y=\mathbf H\mathbf s+\mathbf n$,now we do the SVD to the $\mathbf H$ If the $\sigma _1$ is the ...
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### Does zero-forcing equalizer need known channel impulse response?

I'm studying some of the basic equalizing structres and I understand how Zero-forcing works, but it seems to me that a known channel impulse response is needed. Am I right? If so, what's the point? I ...
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### Types of equalizers

I can't get my mind around the different types of equalizers and the difference between some of them. I've been looking at different books unsuccessfully. So far, I have Wikipedia's list and this ...
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### Real Fast Fourier Transformation (FFT) in 2D changes with changing the axes order

I am using Python to calculate the real FFT for a 2D array. I found that the real FFT function does not return an array with the same size as the input array, rather, it returns an array with the same ...
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### we have already know the number of null space,Why should we still do SVD when we want to use null space to cancel the interference?

What is the true meaning of using SVD when we use null space to cancel the interference signal ? I mean why when lots of paper mention that they use null space to cancel some interference signal ,...
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### Does orthogonal beamforming mean $\mathbf f_a \cdot \mathbf f_b =0$?

If i said that these two beamformings $\mathbf f_a$ and $\mathbf f_b$ are orthogonal to each other,does it mean $\mathbf f_a \cdot \mathbf f_b \approx 0$ ? Because i have see two paper about ...
20 views