Electrical Engineering Stack Exchange
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Questions tagged [digital-communications]

Related to all communication systems that use a given digital sequence as an interface between the source and the channel input.

Digital communication systems, by definition, are communication systems that use such a digital sequence as an interface between the source and the channel input (and similarly between the channel output and final destinaton).

Reference Document

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Examples of fluid (including air) being used to transmit digital data?

We usually use electrons to communicate data across wires, and sometimes we use light also. Does anyone know of real world example systems that use fluids (including air) to do this, and the advantages vs using wires? When I search for air pressure…
Ryan Griggs
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How does ASK account for attenuation?

I'm reading about amplitude shift keying, where 2^n assigned amplitudes of a carrier map to n bits per symbol. Unfortunately, most of the introductory material only covers OOK, where n=1 and decoding is trivial. For an ASK system where n > 1, i.e. a…
Reinderien
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choice of parity bits for linear block codes

We know that in linear block codes the codeword for a given a message is generated by multiplying the message with the generator matrix G . The generator matrix consists of a sub-matrix which is the transpose of the submatrix of H matrix which…
danny gotze
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Long Wires & Digital Chips

Is there a way to send digital signals over long wires(2-3 m)? Can I use buffers to do so? Is it efficient enough.
Sherby
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I and Q from a time series

Say I have a QPSK signal transmitted at a carrier frequency of 5 MHz. The message rate is 100 kHz. If I use a Tektronix scope or data acquisition box to digitize and capture the signal (not a direct conversion to baseband) I get a "real" time…
RobbieK
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Transmit OFDM EVM Measurement

At the same output power level of a power amplifier and for the same number of subcarriers would the measured EVM be different for a QPSK - OFDM signal than a 64 - QAM OFDM signal?
cesar
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Coded OFDM, interleaving, sensitivity, and narrow band interference

Coding (which is a controlled redundancy) and interleaving across sub-carriers protects OFDM signals from a narrow band interferer (CW) that could destroy one subcarrrier. It provides a kind of frequency diversity Suppose we have an AWGN channel , a…
ali khalil
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PAPR (Peak to average power ratio) of OFDM signals

Will the PAPR of an OFDM signal using QPSK modulation on its subcarriers be different than the PAPR of an OFDM signal using QAM256 on its subcarriers? assuming the same number of subcarriers
ali khalil
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What is the effect of redundancy coding on the bit error rate?

If I have a channel with bit error rate BER = \$10^{-3}\$ after modulation, but this is too high so I decide to add repetition coding. With 2 code words and block length of 3 such that I have a minimum hamming distance of 3, giving the system…
Joakim Hansen
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In wireless communication, what is "channel length"?

In wireless communication, I am confused about what people are referring to when they use the term 'channel length.' Can someone explain the term or provide me a definition?
BEENA AO EC
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Decision feedback equalizer

I have a question regarding the implementation of MMSE-DFE. Here is the conventional block diagram: The signal y shown in the pic is, for clarification, y(kT) i.e. the signal y(t) coming out from the matched filter (not shown in the pic) sampled at…
Javi
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'FEC limit BER' in communication systems

What is the maximum BER that a FEC can correct? In one of the IEEE papers the value mentioned was 10^(-3). My question is when FEC can correct BER upto 10^(-3) then why do many communication systems specify BER requirements to be 10^(-12) to…
Abhilash A
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ATTINY85 sending byte to another device

As far as I understood ATTINY85 doesn't support serial communication. I'm trying to understand how to do this via code. Is is possible to specify BAUD rate or set some kind of communication speed rate and use a register like this to send a value? …
0x29a
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Monitoring serial communications between two PCBs?

Someone was asking me if it would be possible to monitor the serial communication between two PCBs and output something that is readable. The PCBs are part of an automatic door system - I'm not sure of the baud rate, protocol, or anything right…
THEMuffinMan7
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Suggestions for robust communication between electronic modules

I have to design an industrial system that is comprised of several modules. The system consists of one "master" and several "slaves". As the roles imply, the master will coordinate communications and poll the slaves. Let me show you the way these…
m4l490n
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