Questions tagged [communication]

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

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1answer
89 views

Improving signal communication over distance

Knowing that Wi-Fi on 2.4 GHz has a good signal strength when there are 50 m between the access point and the unit that transmits the data. I want to transmit this data over a distance of 1.5 ...
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2answers
364 views

How does a CDMA Rake Receiver work?

If we dont know the channel coefficients but assume that we are sending a bunch of training symbols how does the receiver estimate the channel coefficients and how often should we estimate these ...
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2answers
952 views

high speed microcontroller - pc communication

I have a project where I have to sample a 4 bit bus every 100ns continuously for a data logging application (I need very low sampling jitter as well). I have a uC that can go up to 300MHz so speed isn'...
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1answer
199 views

Relate phase velocity and velocity factor (transmission medium)

I want to derive the velocity factor \$v_f\$ $$ v_f=\frac{1}{c\sqrt{L'C'}}\tag 1 $$ and this relationship with the phase velocity \$v_p\$ $$ v_f=\frac{v_p}{c}. \tag 2 $$ \$L'\$ is the inductance per ...
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2answers
80 views

Why we don't use pull down resistors for implementing I2C protocol ? And why resistance value varies in I2C depending on its speed?

I have read that we have to pull-up the SDA and SCK lines because the lines are open drain/open collector. But I don't understand why can't we use pull-down? Secondly why the value of resistance ...
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1answer
1k views

Differences max485 and max13487

In my application, I need to transmit data between two arduinos, one as a master and the other as a slave using 485. The arduinos are connected to these modules, which have a Max485: Schematic: With ...
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1answer
739 views

How to use Esp8266 to communicate between Arduino and Raspberry Pi? [closed]

I need to read 8 sensor values from Arduino and send it to Pi through Esp8266. Also after reading these data my pi will give back 6 other values (integers) which has to be received by Arduino again ...
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0answers
58 views

How to determine best wireless technology for my application

I'm trying to help a buddy research implementing some form of wireless communication between a dozen or so self-contained sensors to collect data placed outside around a small area (less than 20ft ...
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3answers
125 views

Why does the frequency response H(f) exhibit conjugate symmetry in case of a linear system with real impulse response?

The frequency response H(f) is a complex quantity. So, it can be expressed as: $$H(f)=|H(f)|exp[j \beta (f)]$$ Why in case of linear system, having a real valued impulse response h(t), does the ...
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1answer
51 views

Problem making an OOK current signal using pvcvs

I am trying to make an OOK current signal using pvcvs in cadence (I tried pcccs but i couldn't find out what the settings were and it didn't work), and in order to change the output to current i used ...
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4answers
3k views

How to transmit data over a long distance at a affordable price

Please do keep in mind that I have no background in electronic communication. The idea is to receive data from electronics at long distances. The distance I will be looking at to read data from ...
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1answer
69 views

When supply fan VFD starts up it causes communication problems for my energy management controller

We have an energy management system that controls the air handlers for a building. I have one unit that when the supply fan VFD starts up it cause the unit controller to start having communication ...
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1answer
63 views

What is the name of the syntax standard Keithley is using for remote control over serial?

Keithey (and other manufacturers) have a standard syntax for communicating over serial. Typically, commands look like (source): ...
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2answers
474 views

Propagation comparison between 868 MHz, 915 MHz and 2.4 GHz

I am looking for literature for Comparison between 868 MHz, 915 MHz and 2.4 GHz wireless communication system. For example under what condition I should use 868 MHz or when I should not use 868 MHz. ...
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1answer
54 views

How to send data from simple digital device to an Android application wirelessly?

I am trying to find a way to send measurements from a digital device (as the blood pressure device) to a mobile application that can analyse these data ..... How to send these measurements wireless ...
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1answer
244 views

Have mechanical butler's bell, would like to ring it with push button

I have been recommended to post here! Basically I have a butler bell which I'd like to ring from a few floors away with the use of a push button. I have arduinos, ethermegas, spark/particle core, but ...
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2answers
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
764 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
139 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
226 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
566 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
73 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
388 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
161 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
187 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
793 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
877 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
306 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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2answers
196 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
467 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
104 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
94 views

Communication between two Bluetooth devices [closed]

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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2answers
111 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
108 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
2k 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
97 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
127 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
5k 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
454 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
104 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
111 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
361 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
937 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
127 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.