Questions tagged [communication]

Exchange of information between devices. Communication can be wired or wireless.

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1answer
2k views

Which RJ45 pins should I use for power supply?

I'm somewhere in a process of creating mini automation system for hobby use. I've already put CAT 5e cables with RJ-45 connectors in walls. They are somewhere between 5 - 30 meters long. On one side ...
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3answers
686 views

Does narrow-band communication have any advantage over wide band communication? [closed]

Generally more information can be transmitted if the bandwidth of the signal is higher, but is there any advantage of keeping the bandwidth as low as possible?
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3answers
130 views

SPI/I2C chip, CS# pin pullip for I2C operations

I have a question regarding all sensors offering to work in either SPI or I2C mode. I am having some issues working with a MPU9250, but think it is a general question: When working in I2C, the MPU ...
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2answers
212 views

Two way communication between one master and multiple nodes

I have an architecture like this: Master - It contains an RF communication chip. All nodes rely on Master to receive and send data to a central unit. Node - It has some basic GPIO functionality. ...
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2answers
532 views

SIM7100 GSM Modem Unreliable Connection

I am trying to communicate with SIM7100 GSM modem but I could just rarely communicate with it across UART interface. I am observing the signal with an oscilloscope, I am giving 5V as High and 0V as ...
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1answer
72 views

Is there a network mapping tool for path-loss?

I am not sure if this is the proper forum. I am looking for a tool to evaluate the wireless network performance.For example, given a map where should I put a transmitter/or transmitter plus repeater ...
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2answers
111 views

Controlling a circuit through a cat5 cable [closed]

What I am trying to do is to digitally send a signal through a cat5 cable. I wan't to send it digitally so people can't just come along and put a voltage on the wires to activate the circuit. I would ...
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2answers
357 views

How does data travel correctly over the wire?

I understand that through varying voltage, data can be transmitted as "high" and "low". What I don't wrap my head around is how the receiving end "dissect" the frame. I know there is a concept of ...
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3answers
157 views

Role of Coax Cable in bringing TV signal to our TV sets

We know that we receive the programs/shows of TV Channels from the producers of programs through CATV Service providers (almost obsolete, just wanted to get clarified on its working process) DTH ...
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1answer
178 views

How Gigabit Ethernet is achieved in fiber optics?

I understand how 1000BaseT works on Cat 5 cables: It uses clock rate at 125 MHz, 4D-PAM5 data encoding to transmit 2 bit per cycle and it uses the four pairs of the cable. The math is quite simple: ...
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1answer
728 views

Can I use a RN2483 to make a LoraWAN gateway?

I have a Microchip RN2483 LoRaWAN module and I would like to use it for making a LoraWAN Gateway. Is it possible? If it is, how can I do it? Or if it is not, why?
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6answers
3k views

Is it possible to transmit square waves EM signal through air?

Can we transmit any signal other than sinusoidal through air, if yes how and if no why ?
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2answers
825 views

Is the communication between the USB or PS/2 keyboard and the computer simplex, duplex or half-duplex (unidirectional or bidirectional)?

I am curious to know if the communication between the computer and keyboards is unidirectional or bidirectinal. Until a few days ago i thought the communication is unidirectional because only the ...
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2answers
300 views

Fundamental Minimum Noise Floor

I am interested in what are the fundamental limits for communication, theoretically of course, practically there many be many other limits. So I have tried to formulate a minimum noise floor for a ...
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1answer
128 views

S/N Formula with probability

Hello I am looking for the S/N formula that incorporates the probability of catching the signal, and setting an arbitrary treshold level above which we detect the signal. I can't figure out the ...
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2answers
455 views

VHDL: Receiving Data from Terminal to FPGA using TTL

(I posted same question in stackoverflow but didn't get right answer) I'm newbie in VHDL. So today, after UART Tx, I tried to read Datas that coming from Realterm terminal. I only wrote Rx codes to ...
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2answers
69 views

Pulse Shaping Inquiry

I am really confused about how several books and videos handle Pulse Shaping.In order to avoid ISI (Inter Symbol Interference: Energy from one sample leaking into the energy of the other, creating ...
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1answer
103 views

Using lower frequency signals to transfer data

I am working on a system that should transfer some integer data on a distance of couple of kilometers in a mountainous area and should be as cheap as possible. I've read about LoRa modules and the ...
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1answer
81 views

Communication between two Bluetooth devices

My supplier tells me that communication between 2 bluetooth devices requires authentication by an app. When reading online I believe it should be possible, but am not 100% sure. One article from EDN ...
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1answer
94 views

AM modulation circuit modification

I have an assignment on AM modulation. I implemented a circuit and the output wasn't exactly correct, the output is not symmetrical about the x-axis. I'll post screenshots which might explain the ...
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4answers
104 views

How to regulate voltage at receiver in Visual light communication

Consider an LED, transmitting data which is stationary and a moving receiver placed on a car. There is a photodiode which receives the data. The car moves at a speed, when the car approaches the led ...
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2answers
1k views

Data transfer from Microcontroller to computer [closed]

I'm looking for a good link to data from Microcontroller to computer. I do not know what kind of communications is suitable for me. I need a link which has a bit rate more than 50 Mbit/sec. and also ...
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2answers
96 views

Displaying data in engineering units on desktop [closed]

Suppose I have 100 numbers of DSPs whose ADCs are converting analog data into digitals ones. The data may be current,voltage, frequency etc. Now DSP deals with counts only it does not understand ...
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3answers
126 views

Is the Signal-to-Noise ratio arbitrary?

It looks to me that the Signal-to-Noise ratio (SNR or S/N) is completely arbitrary and it's set by the user according to his preferences. Sorry I am amateur on the subject but I don't see any ...
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8answers
4k views

Is it possible to receive information if the received power is below the noise floor?

This relates to my previous question, which I think I have asked in the wrong way: How to insert background EM noise into pathloss equation? I wasn't really interested in detectability of the signal,...
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1answer
423 views

GSM antenna inside metalic enclosure

Is there any efficient way to make an antenna radiate to the outside from inside a close metalic enclosure? I cannot drill any holes in it, nor place the antenna on the outside, nor change the ...
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1answer
103 views

How to insert background EM noise into pathloss equation?

I am trying to understand how to add the background noise into the equation. I am trying to work out the pathloss of a radio signal over a certain distance. We have the Friis Formula for that for ...
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3answers
110 views

1-11 Hz to DC voltage signal

I'm doing an internship where we are connecting all kind of sensors on a CAN-network for an automated datagathering. There is one sensor that sends a 50% duty cycle frequency signal between 1 and 11 ...
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4answers
345 views

Self-clocking driver / transceiver

I'm looking for a way to transmit a clock signal and data over a single line, perhaps using a self-clocking signal such as Manchester coding. The design I'm working on has a number of chained units, ...
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3answers
7k views

How is 255 Tbit/s processed in optical fiber communication?

I have never understood how the new record breaking data transfer speeds are achieved in terms of converting from/to electrical and optical signals. Suppose we have 255 Tbits of data and we want to ...
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3answers
913 views

Is RS-485 a suitable physical layer for Atmega chips in a home monitoring situation?

I am intending to build some Atmega based home monitoring chips. I want to monitor temperature, humidity, and current levels. Current level monitoring would be done with an inductive pickup on AC ...
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3answers
125 views

Simple wireless transmitter for notification when circuit turned on

I have a simple home project I'd like to implement. Being a electronics newbie I'm not sure exactly how to go about it. Basically, I'd like to build a device that is attached to a (12V) power supply ...
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0answers
54 views

Place of matched filter in fiber optic communication

In short-haul communication via optical fibers, we use photodiodes (PD) to detect the light. So if we want to use a matched filter, should we use it before the PD (optical domain) or after the PD (...
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2answers
163 views

Can someone please explain how this circuit works

It's s simple transmitter for light modulating certain sound we input to it. But i can't seem to know how this modulates the input signal.
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2answers
209 views

Is a current signal more robust than voltage signal from noise? Why?

I am trying to transmit a 3.3V digital signal over 20 cm distance. The problem is the environment might be noisy because of high current wire near it. I read that current signal is more robust than ...
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2answers
223 views

By data processing inequality, by processing we are losing information. So why do we process the data?

From data processing inequality(DPI) we know that if \$Z=f(Y)\$, then \$I(X;Z)\leq I(X;Y)\$. However, in the application, we process the data. For example, we pass the received signal via a matched ...
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4answers
186 views

Multilateration with TOA using lowcost transceivers (like NRF24L01) and uCs

My problem is the following, I would like to localize an object (main node) via multilateration using a wireless sensor network of 4 nodes with less than half a meter accuracy. The equations are ...
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3answers
147 views

Which interface should be used for communication between processors?

I have two processors (STM and Infineon) on the same board and I have to organize communication between them. Yet I'm using Ethernet to communicate between them, but a startup time of Ethernet after ...
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2answers
85 views

Magnetic induction on data lines from DC power lines

I have experienced failures of RS-485 links due to magnetic induction from ~52V battery power lines running very close in parallel. Standard shielding around the RS-485 cables did not solve the ...
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4answers
801 views

Antenna concept, is it a passive device but how about gain?

Cisco antenna explanation Here it says that antenna is passive device which doesn't offer any added power to the signal. But at same time it says that antenna is responsible for increasing the ...
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0answers
196 views

Circuit to drive a telegraph sounder?

I acquired an old telegraph sounder, marked Western Electric 140 Ohms, and have a Morse code key. What voltage should I drive the sounder with to hear the proper Morse code click sounds when keyed? ...
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1answer
80 views

How to represent binary for differential and Menchester coding?

I have some questions with solution provided from random material, but I can't understand well. Question 1: I tried to represent binary for each block according to description in the picture above, ...
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2answers
107 views

Correct definition of transition in line coding

Hello I have following question and it says: I basically cannot understand this solution. My questions: isn't it a sequence of 4 0s followed by 4 1s? (answer says 4 1s followed by 4 0s) since ...
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1answer
2k views

Esp8266 nodemcu v3 connection to usb fingerprint scanner

My project is about making an ioT biometric attendance management using Esp8266 nodemcu and a Morpho usb biometric scanner. So my question is whether is it possible to connect a usb fingerprint ...
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2answers
74 views

High speed data interface for upto 5 meter

I have to interface two processor boards sitting at a distance of about 5 meters away. The data transfer rate is about 128 MBps (Mega Bytes per seconds) or 1 Gbps(giga bits per seconds). Which ...
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2answers
252 views

UART Floating Voltage on Custom PCB?

I'm testing my first ever PCB design, which is based on an ATMega328, and I've come across some undesirable behavior with the UART: When I have the UART connected to my computer through a FTDI USB ...
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2answers
296 views

No ACK from slave device

What are the possible problems for slave to not give ACK (pull down SDA line) after 8 bits of data? I can see 8bits (slave address) with osciloscope, but the ACK is high at 9th bit clock pulse, why?
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2answers
47 views

OFDM demodulation time

How much time does it take to demodulate one OFDM symbol? In 802.11a standard the Symbol Interval Time is 4us. Does this mean that each symbol is demodulated within this period or there is pipelining ...
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2answers
143 views

Sending data from MCU to PC with 1.5 Mbaud using FT232R

I have an issue using FT232R to communicate with my PC. I have two bytes of data that I need to transfer every 50 us. The frame size is 20 bits, including two start and stop bits for each byte. I've ...
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2answers
70 views

What are bus reliability method? [closed]

Busses provides to IC the ability to communicate to each other. But this communication can be blurred due to noise coming from or outside the circuit. I know there is ways to lower the impact of ...