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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Why does USB have 4 lines instead of 3?

USB specifies 4 pins: 1. VBUS +5V 2. D- Data- 3. D+ Data+ 4. GND Ground Why is this not 3? Could the Data and Power not share a common ground? Am I correct in understanding that D- is the ground for D+?
Mark Harrison
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Why is digital serial transmission used everywhere? i.e. SATA, PCIe, USB

While looking at SATA, PCIe, USB, SD UHS-II it struck me that they are all the same: digital serial bitstream, transmitted using differential pairs (usually 8b/10b coded), with some differences in link/protocol layers. Why so? Why did this become…
artemonster
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Can a premium HDMI cable outperform a standard cable?

Assuming two cables both conform to the same standards (e.g. HDMI2.0, high-speed, ...) is it possible that a premium cable will outperform a standard cable when using an objective benchmark that measures the quality of picture/audio? Or what…
zr.
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SPI or I2C: which to use for a longish bus

I'm contemplating a project that would require several AVRs talking to each other over a bus. They'd be separated by as much as 6 feet. It seems like both I2C and SPI can let a series of micros communicate over a bus, but I haven't seen anything…
edebill
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I2C 3.3 to 5.0 V conversion

I'm trying to interface a 3.3V I2C device to a 5V Arduino. I don't have any problem with SCL line. I can use a simple voltage divider but I have an issue with the SDA line as this is bi-directional. I'm not at all sure how to handle this. I have…
JohnC
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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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Could data transmission power consumption be lessened by transmitting more zeroes?

According to the IEA 250 TWh of power was consumed in 2019 due to data transmission globally, about 1% of worldwide electrical power use. I would like to pose a very simple question regarding power consumption in data transmission. Does it use more…
Fiach Reid
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What is a Patty Code?

In my digital logic lecture today, my professor introduced a symbol code called Patty Code. I copied this table off the whiteboard: | Symbol | Binary | Odd Patty | Even Patty | |--------+--------+-----------+------------| | a | …
Winny
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transmitting 5v signal over a long cable

I'm seeking for help here as I need a reliable answer to this. I need to get an input signal (low frequency 5v digital pulse), to a micro-controller from a (proximity) sensor situated in a distance from the control board. I'll itemize the important…
Codenamed SC
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Is there any way to use half-bits?

As most people here know, by using 4 bits, we are able to count from 0 to 15 (0123456789ABCDEF in hexadecimal). But if we were to only count up to 9, we would still be using 4 bits, and the digits from A through F would be wasted. However,…
Galahad78
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HDMI and I\$^2\$C

I was having a look at the HDMI pinout and I thought: why would they use I\$^2\$C for the display-host communication? My question here is about the design metrics that lead to this choice. HDMI is a quite recent standard while I\$^2\$C is around…
Vladimir Cravero
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Communication among briefcase halves

I'm building a small laptop-ish device in a briefcase. Imagine the green wires aren't there. The LCD half lies somewhat deeper in its case than the keyboard part. For now, testing and programming, I'm using four wires (2x I2C, ground, 5V) to…
user17592
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Why AT command set?

Frankly, Why do all communication ICs(or at least many of them or most famous or popular) such as Bluetooth or WIFI or GSM or etc support AT command set? why don't they have a simple pin for D/C(Data or Command) for communications? What are the…
Roh
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How can over 24 GHz communication be possible?

I read the article Google wants the US' wireless spectrum for balloon-based Internet. It says to use over 24 GHz frequency spectrum for communication. Is it ever possible to generate that high frequency by using piezoelectric crystals? Or are they…
tcak
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Is it possible to send multiple data bits on a single wire at once?

Is there an existing protocol or modulation method where multiple data bits are sent over a single wire at once or maybe an additional ground line (like serial communication)? I know there are methods like PSK or FSK where phase or frequency of…
CrownedEagle
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