Questions tagged [communication]

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

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Increasing satellite communication capacity - bullet point list help [on hold]

What are the major drivers for increasing satellite communication capacity? Bandwidth (Nyquist theorem) Frequency reuse via multiple spot beams in an antenna coverage area Higher SNR gives better BER,...
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136 views

Decay rate of Filter and how it relates to transmission speed

I had a question with regards to the decay rate of filters and how it responds to transmission speed. Suppose we have implemented a simple BFSK system with two asynchronous receivers and we have a ...
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115 views

Setting up a 485 network

I have a problem where my 485 transceiver just get damaged at field, when it's at laboratory everything runs fine, now reading about it I saw that 485 requires a 120Ohm impedance on both ends and bias ...
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2answers
73 views

Is there a method to get the carrier from the recieved QPSK signal?

If we have given a signal and we know that is a modulated QPSK signal, can we recover the carrier if we know the carrier frequency fc. Edit: A clarification, I do not have to do it in hardware, a ...
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22 views

Using arduino to get data from a smart sensor that uses SDI communication protocol [on hold]

I am using Arduino mega to get data from a smart sensor that uses the SDI 12 communication. Can someone help with the Arduino code and exactly explain the the role of SDI communication protocol in ...
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72 views

Lack of 'determinism' in Ethernet bus

While reading this website, I found out tha there is lack of 'determinism' in the Ethernet network bus as compared to some other buses like 1553. What I understand is that Ethernet is a single master ...
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2answers
110 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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63 views

UART - I2C interface [closed]

I want to implement an UART to I2C protocol converter board, similar to the USB I2C click of MikcroElectronika which is USB to UART/I2C converter board using the MCP2221 of Microchip. Should I use a ...
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79 views

What is used as a rotary join in Lidar system? [on hold]

I want to transfer data between a rotary platform mounting an antenna and a PC, so I can scan for a signal at 360 degrees. I could use a slip ring but there is a loss in signal. I want to transmit ...
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177 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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33 views

what's up with u-law companding when u is 0

https://www.tutorialspoint.com/principles_of_communication/principles_of_communication_modulation_techniques.htm It says that I can get the compressed output of a signal using this: it also says ...
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2answers
239 views

Noise resilient, hot-pluggable communication bus over long cables?

I'm working on a setup, where we need communication between a master device and several slave microcontrollers distributed out in different boxes connected by "long" cat5e cables (3-10 meters) The ...
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32 views

What is the difference between residual phase noise and absolute phase noise?

Studying the characteristics of an oscillator with a phase noise analyzer, but I don't quite understand the difference between absolute and residual noise. Any help would be greatly appreciated
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155 views

How to interpret this CAN bus data and find an equation?

I am trying to reverse engineer the data sent from an old CAN bus data logger. It sends a single ID which is selectable from a dip switch. The only bit of data I am struggling with is the RPM I plan ...
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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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171 views

SPI read error with MCP2515

In an attempt to interface a motor controller, battery management system and maximum power point tracking device on a CAN bus, I used the MCP2515 and TJA1050 CAN breakout board. All these devices send ...
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18 views

Foster - Seeley FM Demodulator Explanation

Consider this Foster Seeley Demodulator If I have correctly understood, its basic working principle is the fact that at the secondary coils (L2) of the Balun there will be two signals equal and ...
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1answer
281 views

Bandwidth-Noise-SNR relationship

Let’s say we have the noise figure F of a system of devices. We also have the bandwidth improvement coefficient ( as defined by my teacher ) $$BI=10log(\frac{B_{in}}{B_{out}})$$ where B1 is the ...
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66 views

Can we band pass filter QPSK signal?

Consider we have QPSK signal with carrier frequency 10kHz. Generally, we demodulate or use matched filter on the the QPSK signal and recover the transmitted bit or the symbols. If the QPSk signal is ...
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1answer
135 views

ETSI[Europe] Regulations for 2.4Ghz ISM Bandwidth Limit and RF Power

I am trying to interface my STM32 with NRF24[2.4 Ghz ] or TI CC2500[2.4 Ghz] models. I am finding issue regarding maximum allowable Bandwidth and RF power set by ETSI[Europe] EN 300 328 and EN 300 440(...
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39 views

How can line code polarity inversion happen?

One of the disadvantages of some line codes like NRZ-L or RZ is that if a sudden change in polarity occurs, then all received bits will be erroneous (flipped). How can such a sudden change in ...
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3answers
133 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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1answer
8k views

LIN-communication between two STM32F4 with a standard LIN-transceiver (Hello World)

I have the following circuit connecting two stm32F4 via the SN65HVDA195-Q1 LIN-transciever. simulate this circuit – ...
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21 views

NB-IoT/CAT-M1: Llimitation to the actively connected devices

For the new Cellular IoT technologies NB-IoT and CAT-M1, is there a limitation to the number of modems that can be connected to the base station at one time? I tried searching for this but I couldn't ...
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2answers
101 views

Measure voltage on 48 batteries at once using microcontroller

I am looking to design a microcontroller that can measure the voltages on 48 batteries. Some of the batteries will have floating voltages as the device is wired in a parallel string of 8 columns, with ...
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30 views

MCP2561/2562 CANbus voltage?

The datasheet says the MCP2561/MCP2562 is suitable for 12V and 24V systems except that everywhere I look in the datasheet it says VDD needs to be between 4.5 to 5V. How can CANH be greater than VDD or ...
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101 views

Extremely low data rate transmission over long distance for attinys

For a lighting project I need to be able to trigger 20 units every couple of seconds independently which are daisy chained with 1-2 m space between each of them like so: Control station ====== Unit 1 ...
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1answer
848 views

How does modulation technique affect channel capacity?

Shannon's channel capacity formula does not consider modulation techniques. How then does LTE achieve high data rate using advanced modulation techniques? P.S: I am novice in RF and signal processing....
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39 views

Are magnetically tunable surface acoustic wave devices commercially produced?

I have been reading up on studies of magnetically tunable surface acoustic wave devices, in general they note the relative velocity change or in some cases a frequency shift if it is part of an ...
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1answer
951 views

PIC16F1619 curiosity- UART communication

I am using the PIC16F1619 microcontroller within the curiosity board, MPLAB IDE x and XC8 compiler. I am currently trying to get my board to read an analog value and then to transmit this value ...
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1answer
362 views

SPI with differential signaling

Standard SPI uses single-ended signals. Is it possible that a communication uses SPI protocol but the signals are physically LVDS?
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1answer
186 views

What kind of communication protocol is this?

I'm trying to reverse engineer the communication between two modules, a master and a slave, but I couldn't figure out the used protocol. All of the signs use 5V. The blue sign's frequency is 400 kHz. ...
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67 views

Communication between device for 5 meters and low speeds

I need to make a communication between only two devices with a distance of 5 meters, which are connected by a cable of 4x2.5mm² (see in the image), being 1 wire for GND and wire for 12v, that would ...
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1answer
92 views

What chips can be used to design an Anti-Counterfeit /Authentication circuit? [closed]

I am an intern within the R&D branch of a company that designs tools that must operate with low noise at extremely high external temperatures (upwards of 175C). My boss asked that I look into ...
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11 views

Xbee Router in API mode not sending frames from UART input?

My current system is setup as follows: MCU ------ Xbee A(Router) ------ Xbee B(Coordinator) Xbee A is a router in API mode, Xbee B is a coordinator in API mode. MCU is MSP430, Xbee modules are ZB ...
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232 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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1answer
42 views

Can I use a Ku band satellite dish for Wi-Fi?

Satellite TV works at 18-24Ghz and WiFi at 2.4Ghz, will a T.V dish antenna work for WiFi? Diameter of the dish is about 60-90cm
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57 views

Digital transmission of composite video [closed]

As the tittle suggest, I was thinking about making a wireless composite video transmission between a small camera (such as those sold for flying fpv) and a receiver. The two main specs it must have is ...
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3answers
594 views

Symbol vs. Word (Digital Communication Theory)

So I'm trying to understand and link up the different chapters I've studied in a communications module. So here goes I understand a Pulse Code Modulation System is made up of the following broad ...
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63 views

Demodulation of a 38 kHz IR PWM signal

I want to learn how to demodulate a 38 kHz IR PWM signal.(Such as that transmitted by a TV Remote Control) I know it can be demodulated easily using a TSOP1738 IR receiver. I realize that the ...
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3answers
60 views

Does data rate increase with channel frequency?

It is commonly said that a higher channel frequency implies a higher data rate. For example, in https://www.howtogeek.com/222249/whats-the-difference-between-2.4-ghz-and-5-ghz-wi-fi-and-which-should-...
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1answer
60 views

How to calculate the 3dB point?

I understand this until the final two lines. How does he get from 27.8766 to 1149.8hz and 7224.7rad/s?
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1k views
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1answer
66 views

Bluetooth vs BT Beacon [closed]

While trying to understand how BT devices work I came across another related term "BT Beacon". Is it same as BT communication or if a device is termed as BT beacon then it would have some specific ...
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13 views

Average and maximal number of time slots in adaptive tree walk protocol

I was wondering if it is possible to know the maximal and average number of time slots that will pass until and including the time slot in which there will be a successful broadcast, knowing that two ...
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2answers
1k views

Why do we need bit scrambling when using 8b/10b?

I want to ask the opposite of this question. Here are the purpose of the bit scramblers: Encrypt, but LFSR (and other used) bit-scramblers are breakable. Clock recovery, but it is done by the 8b/ ...
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1answer
205 views

Look up tables for 8 digit display

My project on STM32f407-Discovery. I will send a message on terminal to my board and I use this message for showing an 8-digit display. I am trying to build a look up table for the 8 digit Display. I ...
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44 views

I/O expanders- CAN & I2C

Currently in my system we use 16 I/O expanders with I2C interface. I want to change it to CAN interface. Which is the best possible way without compromising the cost? I tried searching for 16I/O ...
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2answers
96 views

Transmission of information in terms of information theory and protocol

I am a student studying wireless communications. First of all, I learned that In AWGN channel, i.e., y=x+n with n~N(0,sigma^2), the amount of information that can be transferred (i.e., capacity) ...
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338 views

CRC hardware implementation

What is the difference between these two implementations as the feedback is in first implementation the last reg only but the second implementation last reg xored with the input bit, so, what is the ...