Questions tagged [communication]

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

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90 views

TCA9548A (I2C multiplexer) works for a few minutes and then hangs

I'm having trouble getting the TCA9548APWR to communicate for longer than a few minutes. I'm only able to get it to "reset" by resoldering it. I have used both an Arduino Mega and a Beaglebone Black ...
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29 views

Antenna formed from the RF module shielding wall and cover

Can anyone provide details how an antenna can be designed from RF module shielding wall or cover? More specifically if any company is making this kind of antenna product for general communication or ...
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1answer
44 views

How is the power calculated for Si(t) in the picture?

The formula I've seen is to multiply the signal by its complex conjugate, then integrate across the time period interval, and then divide by the period. But when I do that I don't get A^2/2
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85 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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25 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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1answer
143 views

How does Nyquist bit rate formula relate Bandwidth, Signal Rate, and Bit Rate?

I know what each of Bandwidth, Signal rate, and Bit rate mean. But I am having trouble in their mathematical relationship with each other. I will use the notation of the textbook I am reading from (...
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53 views

a tricky question regarding CDMA with 4 stations

i have encountered this tricky questions that left me really confused, would really appreciate your insight regarding it: given a cellular system with four stations that utilizes CDMA. given the ...
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32 views

Data communication in power harvesting project

I want to design a wearable gadget for elderly to detect falling. This gadget should work by energy harvesting. Now I want to find the best effitient way of power consumtion to send data to a station ...
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3answers
91 views

Choosing best bus and protocol for ~128 clients over the wire

I am up to design system with ~128 MCUs communicating to one MCU master. Communication will be bidirectional. Data will be mostly sensor reads, but I plan to use the bus also as communication method ...
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1answer
44 views

What are the factors that affect delay/latency between base stations?

I am modelling a 5G network, with the uplink and downlink being decoupled and treated as separate networks. I am exploring the integration of fog computing and how latency varies between different ...
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45 views

Intercom device, door-opener and door-bell

I got a Bticino intercom system (non-wireless). I did some restoration in my hallway and disconnected the device. Unfortunately I do not remember how it was wired before I set it up afterwards. Now we ...
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42 views

Wifi coaxial cable type unknown

Quick question, I was unable to identify the coaxial cable type used in wifi devices(routers ,tablets,etc.) , very thin grey cable approximately 1mm in outer diameter, I need to know the type so I can ...
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1answer
106 views

How do I stop signal looping with I/O port in this communication system

I am still a student. When I am designing communication system I am facing this problem: As shown in the figure I need to communicate with Master and Slave. But Master and Slave have single I/O port ...
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78 views

Generating a specific sequence of signals in Verilog with timing requirements

I am a beginner in Verilog, and as a part of a project, I have to send a sequence of signals to a chip in order to program one of its parameters. This Verilog code will be synthesized on an FPGA, and ...
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2answers
71 views

What does the phase discriminator portion of the Costas Receiver do mathematically?

What does the phase discriminator portion of the Costas Receiver do mathematically? The output of the I-channel is \$ \frac{1}{2}A_C \cos \phi m(t) \$. Which means for small deviation of phase \$ \...
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41 views

Does DSB-SC signals retain original shape of the message signal \$ x(t) \$ when \$ x(t) <0 \$?

The conventional DSB-FC AM signal is given by: \$ s(t)=[A+x(t)]\cos \omega _C t \$ In conventional DSB-FC AM we take care of the fact that \$ |x(t) | <A\$. So that the modulated signal is not ...
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2answers
99 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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141 views

How is the power of a SSB-SC signal half that of DSB-SC signal?

Intuitively I get it that my SSB power has to be half of DSB power but mathematically I am unable to get this. Say working for tone modulation. $$m(t)=mA\cos(w_mt)$$ where m is modulation index. ...
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19 views

XBEE S3 PRO loses comms beyond 800 meters with a 7dbi Antenna

My XBEE S3 PRO loses some packets when transmitting 800 meters away from the XBEE Pair. Even though we used a 7 dbi car antenna with sma jack. we used a jack converter from sma to rp sma (if that ...
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24 views

What is the meaning of reciprocal communication range in the context of wireless communication?

Does it mean the carrier sense range is equals to the communication range, as this paper mentions the system has no hidden terminals due to reciprocal range ?
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1answer
65 views

What are the equations/values for Rayleigh Fading, path loss and log-normal shadowing?

I am to use the following equation as part of a model for a wireless communications network: I would like to know the specific parts of the eqautions: "k" - is this the Boltzmann constant? "v" - I ...
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1answer
44 views

Peak-to-Average Power Ratio in OFDMA Communication

I am looking for a formula to calculate the Average Power of a square wave used in APSK Modulation. In my textbook, the example above is given with no formula so I am a loss how the value for ...
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3answers
92 views

Multiple input to single output converter and vice versa

First question so please forgive any mistakes. I'm trying to design a system by which multiple LEDs are controlled by multiple switches, but without using as many wires as there are switch/LED pairs. ...
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1answer
47 views

SPI terminology confusion for project

I am working with the FET335xS-II OBC developed by Forlinx for a school project. On the data sheet, There is no indication of pins pertaining to MOSI and MISO but instead "data 0" and "data 1". I am a ...
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103 views

Does disconnecting the Tx+ and Tx- wires in the ethernet cable make it Unidirectional for Packet (TCP) sniffing

The DCSW-1005(10/100Base-T) Ethernet switch/TAP can be used as a network TAP (as well as Ethernet switch), in which a copy of outgoing and incoming packets associated with Port 1 (Target port) are ...
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172 views

Why is there no reponse from ModbusRTU slave using converter?

There are two devices: Eaton EM20/M (~like Northern Design Cube 400) Volison ADM-5850G Connected them like: Trying to get data from EM20/M which supports ...
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1answer
124 views

SIM800L cannot init

I'm working with SIM800L for remote-sensing communication via GPRS. The problem is, everytime the module is running initialization function (SIM800.begin(), different for every SIM800L library), it ...
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2answers
53 views

Finding required BW with Bessel table

The FM signal (see image 1) is applied to a 50 Ohms antenna, and I am seeking the required bandwith with the Bessel table (image 2). From the FM signal, I deduced that the information frequency is ...
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2answers
79 views

Noise power at receive antenna with finite transmit SNR?

I have seen a few examples of link budgets, and they all assume that the total noise at the Rx is just going to be -174 dBm + 10 log BW. However, this seems to me to assume that the transmit signal is ...
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142 views

How does GSM Module store incoming SMS in its “SM” or “ME” memory?

I am using AI Thinker A7 GSM/GPRS/GPS Module demo v7.1.(The Rx, TX, GND pins of this module are connected to tx, rx, gnd pins of the prolific Rs232-TTL converter and a virtual com port is open in ...
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31 views

Communication Theory - Determine efficiency of this protocol

My solution: I have no idea if what I did is correct. I'm getting a bit confused differentiating between 500 frames/minute and the 4.8Gb/s, they both seem like transmission rates to me. I'm assuming ...
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37 views

Communication Theory - Basic Transmission Errors

I have a question regarding some basic transmission error: My confusion is with the solution to combat errors (transmit each frame 3 times). I would have though that the probability of receiving a ...
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1answer
64 views

Write collision for multiple reads - PIC24 I2C

I am trying to poll a CAP188 sensor so I'm sending it read commands in a while loop, but the first read works and then on the second read when I send the slave address it detects a write collision. ...
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1answer
66 views

Is it possible to generate user-defined signal using an android phone?

Is it possible to generate an electronic wave signal using an android phone? (Theorically) For example by customizing the firmware can I produce some signals like \$ f(t)=2 \sin 3.2×10^9t+3\cos 5×10^...
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2answers
106 views

Maximum rate Shanon Hartley

i am reading computer networks and i am trying to solve an excercise. the excercise is What is the theoretically the maximum rate at which data can be transmitted to a 4000Hz bandwidth ...
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35 views

UART Current in PIC18F46K22 & 7404 Input Current

I am currently making a decision to invert the UART signal from my PIC18F46K22 and have 2 choices to either use 74LS04 and 74HC04 but there is a difference between the LS and HC that the LS can output ...
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2answers
457 views

Why maximum power transfer condition is suitable for communication system but not for transmission of electricity?

A fundamental concept that i have learned from basic electrical circuit study is to receive maximum power by a load of resistance RL from a source the necessary ...
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75 views

Is an external crystal overkill is this case?

I am designing some boards that are powered and communicate through Cat 5 cables using a bit banged form of protocol inspired by quad spi. Using the bus network topology in a half duplex manner, I ...
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2answers
62 views

Is wireless technology only possible due to inductance?

I asked a friend how capacitative coupling works in glass-mount antennas. He said it's like when installing a sound system; where you want to keep the power & audio cables separated, to avoid ...
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1answer
350 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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1answer
31 views

What are cost-effective and ways of providing global communication between two devices besides internet and SMS?

I am currently in the process of building a system which allows vehicles to send information back and forth with an Arduino. The main problem I am facing right now, is that the current implementation ...
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1answer
76 views

How does Wi-Fi deal with multiple frames received at once?

Right now I'm trying to establish a network of 30+ transceivers with NRF24L01 modules - one of them acting as central. However there are big problems, whenever two or more nodes try to send data to ...
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211 views

Honeywell I2C RH Sensor SDA line experiencing fluctuation between Vdd and Vdd/2

I had a problem when implementing I2C communication between NXP Kinetis K50 micro-controller and Honeywell Humidlcon I2C RH sensor. The RH sensor doesn't acknowledge when receiving the default address ...
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1answer
166 views

STM32CubeMX/STM32L0 UART Transmit unknown symbols

I am trying to connect UART communication with STM32L053C8-Discovery. But the problem is on terminal I get unknown symbols. My Setup on CubeMX ...
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32 views

ENC28J60 rejects unicast packets - unicast filter is on, MAC is set, and addresses match

I'm programming an ENC28J60 driver at the moment, and have encountered something odd when attempting to receive packets. More specifically, unicast packets. According to the datasheet, when the ...
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1answer
40 views

Antenna polarization and antenna directivity are the same?

I'm working on an RFID project, and looking for information about the antennas that I have to use, I have the following doubt: Antenna polarization and antenna directiivity are the same? Thanks!
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1answer
96 views

Does this wiring pattern for a DB9 cable exist as a standard cable?

I have a scientific instrument that uses a DB9 cable to connect to the standard RS232 port on a computer for communication. I've deconstructed one of the cables as I needed to make another one but I ...
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1answer
169 views

Current modulator for laser driver and analog audio signal modulation

I would like to build a proper laser driver and use an audio output to modulate the laser output. At the moment, I connected the audio output instead of the battery in a laser pointer. It works, but ...
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2answers
605 views

How does this fire alarm system transmit data on two-wire?

In the fire detection industry, analogue addressable systems use control panels and detectors (and devices such as interfaces) which communicate with each other by means of a protocol. What protocol ...
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2answers
580 views

Communicating between 2 different microcontrollers

My Arduino runs at 16MHz clock speed; another microcontroller runs at clock speed of 13MHz. If I send digital output directly from an output pin of the former to input pin of the latter, there will be ...