Questions tagged [networking]

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SFP proper address to read length

According to SFF-8472, there are 6 addresses (14 to 19) in table A0 for link length. And when I read a couple of SFP modules trough I2C, I see that more than one of these addresses contain value other ...
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3 answers
204 views

SFP, accessing EEPROM?

I have a SFP compatible module which has an I2C interface. I understand that SFP is a pseudo-standard but I can't find any documentation on the I2C interface and what registers in the EEPROM do what. ...
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21 views

Connect 100Mbit GMAC to a 1Gbit GMAC VSC8211

I would like to connect a 100Mbit GMAC on the SAMe70 with a 1000BASE-SX Switch. What will happen if I connect VSC8211 to this device and then attach a 1000BASE-SX Switch? Will the Autoneg on the ...
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Demodulation and RFID Readers

I was wondering if anyone had an inclination of demodulation and packets regarding RFID chips, sensors, and tags. When working with RF signals, and using a reader the device is capable of collecting ...
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14 votes
5 answers
7k views

How am I getting 1 Gbps through a CAT3 cable?

My work from home office, in a difficult-to-plumb part of my house, has an existing CAT3 running to it from the main part of the house. I wanted to use a wired connection because the Wifi flakes out ...
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1 vote
1 answer
436 views

Capacitive coupling Ethernet on backplane

Sorry in advance I am fairly new to the electronics world and Ethernet signaling. I am a physics postgrad student doing some hardware work rather than an electronics engineering background. I have to ...
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1 answer
283 views

What are the Pros and Cons Using a Relay to Bypass LAN with Dual Ethernet Ports after POWER LOSS

EDIT: The Microchip Ethernet controller only supports 10/100 Mbs I have verified on my bench that two Magjacks with magnetics built in, and hard wired together, works on the bench using just the ...
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1 answer
114 views

Why does my ethernet on my custom board only work sometimes?

I have a custom designed board that basically functions as an ethernet switch. On it I have 4 ports 3 with magnetics and 1 without magnetics. I could not use integrated magnetics on all of them ...
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2 votes
1 answer
95 views

How to properly read current of a PoE Mode A device?

I'm trying to measure the power consumption of a PoE device using Mode A. I assume I would need 2x current readings -- one for pin 1 (I1), one for pin 2 (I2), and then 1 voltage reading of from either ...
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0 answers
139 views

W5500 network configuration issues

I have used W5500 hardware for my gateway device. It has been implemented in 80-100 locations. But in 4-5 locations I'm getting an unusual issue related to the network connection. The ethernet mode is ...
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1 answer
62 views

A few questions on modem/AT commands

A couple of questions about modem: I have been reading up on AT commands, and I see they're used to control the modem. They are sent over a serial connection so does that mean they are sent over UART?...
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2 answers
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Power switch in electronics in europe

Are there any requirements towards user electronics working in europe stating that they need to have on/off switches? I am asking especially regarding networked devices. I have seen a lot of unmanaged ...
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1 answer
68 views

Electric vehicle instrumentation [closed]

I have converted a vw bus to 112 VDC electric drive (Tesla battery modules 22.5VDC X 5 ea). There is also a 12V system for lights and instruments. The BMS supports SPI and CAN. I have no experience ...
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2 answers
371 views

How does ISP cut the customer's internet access technically?

We know that if we fail to pay our internet bill then our internet access will be cut. But how does the ISP technically cut the access? For wired internet, do they just shut down the port where the ...
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4 answers
113 views

Is building a long range wifi antenna to connect to the up and coming starlink internet possible? [closed]

I want to try to convert a residential satellite dish into a long range wifi antenna to theoretically see if I can connect to the up & coming starlink internet that is being released in Canada and ...
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1 vote
3 answers
430 views

CAN Bus Dominant and Recessive?

Why does CAN Bus represents signals with an inverted logic, high voltage for a logic 0 and low voltage for a logic 1? Is there any advantage in doing so?
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1 answer
70 views

Use 2 of the 8 cables of an existing ethernet connection

There is an Ethernet cable that runs from a server room to an office. That cable is connected to a router. There are times when ...
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2 answers
69 views

If you only have an Ethernet MAC without higher layer, what happens if packet is lost?

Does an Ethernet MAC have a built in ack/retransmit scheme or is this the job of a higher layer of network protocol? In other words, if you have only the Mac layer and an Ethernet packet is lost ... ...
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1 answer
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MAC data width for 100/40 Gigabit Ethernet system on Xilinx Ultrascale core

If I remember correctly, Xilinx's 10 Gigabit Ethernet Mac core has 32 bits data bus connected at the mac side at 156 Mhz.... What about the 100 Gigabit and 40 Gigabit Ethernet Subsystem in the ...
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1 vote
1 answer
31 views

What hardware limitations limit the number of stations connected to and access point chip?

I am designing a Linux based embedded access point that needs to support as many connected stations as possible. I understand the first limiting factors like CPU, RAM, and available bandwidth. ...
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1 answer
63 views

Are there any disturbances caused by wire of socket which not being used?

Let's say there external wiring that lead to AC power socket. Are there any electromagnetic field or something from the wire if the socket isn't used at the moment (nothing plugged in). What if ...
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2 votes
1 answer
53 views

Proportional fair scheduling

I came across this section in the paper Providing quality of service over a shared wireless link, IEEE Communications Magazine: Consider a very simple system with two users. The service rate (in a ...
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1 vote
1 answer
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Does 10GBASE-R fully replace 10GBASE-X?

10GBASE-R using 64b/66b encoding scheme (3% overhead) 10GBASE-X using 8b/10b encoding scheme (20% overhead) 10GBASE-R is achieved with single xcvr lane 10GBASE-X is achieved with 4 XAUI xcvr lanes &...
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0 votes
1 answer
87 views

RJ-45 with only four wires?

Dig through a junk drawer, I find a long cable with RJ-45 on each end.  Definitely not RJ-11.  It has only four wires.  What might it have been used for? I'm not expert on wired ethernet, but in ...
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1 vote
1 answer
157 views

How to avoid duplicate messages in a mesh network of mcus

I'm working on a project, where each pcb has a connector on every side, so you can connect these board in a grid. It's basically a mesh network of modules. These modules need to communicate with each ...
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-1 votes
1 answer
89 views

Bit-Map vs ALOHA protocol

So i have been reading about ALOHA and Bit-Map protocols and i am note sure which is more preferable in the following scenario: 8 stations, numbered 0-7 want to transmit in any given time slot. ...
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0 votes
1 answer
137 views

Finding the overhead and distance of an unknown code based on message making algorithm

for an information word M with m bits that is coded as following: M is coded into a word A using an unknown code that allows detection of not more than one error. the code word is the word obtained ...
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1 answer
149 views

THINNET 10BASE2 Network using RG-58 Coaxial Cable operating frequecy?

I am trying to figure out what the signal frequency of a 10BASE2 network is. Specifically the frequency of the signal being carried over coaxial cable. Data transfer is 10Mbps and the network adapters ...
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0 votes
1 answer
58 views

Connecting nodemcu through internet

I have a NodeMCU and a website (free website domain provided by hpage.com) and I have to send and receive some data (suppose a 8-bit number) from the website to the NodeMCU via internet. The NodeMCU ...
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0 answers
251 views

Why does 100G Ethernet use FEC while Infiniband doesn't?

The 100G Ethernet physical layer signalling is moving to PAM4 and using Forward Error Correction (FEC) when the lane signalling rate is greater than 25 Gigabaud (Either 4 lanes x 25 or 2 x 50). ...
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67 views

Do Broadcom's Ethernet chipsets need special software to operate?

I want to implement an Ethernet switch using Broadcom's chips. Are singing an NDA and getting the datasheets enough to work with the chips? I have heard that the chips must be programmed by a special ...
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4 votes
2 answers
871 views

Why are length-prefixed fields considered hardware unfriendly?

One criticism of GENEVE (a network encapsulation protocol) is that it uses tag-length-value fields, and these are hard to process in hardware. Why is this considered hardware-unfriendly? What ...
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-1 votes
3 answers
252 views

Does the phone transmit waves? [closed]

In a cellular connection, How much is power density (in W/m2 or mW/cm2) of the RF energy from the phone to the tower? If not possible in above units then can I know in dbm ? My phone has: Head SAR: ...
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-1 votes
1 answer
61 views

Choosing a networking protocol [closed]

I need several mbeds to communicate with a host PC, which will issue commands to individual mbeds. What would be a suitable networking protocol to achieve this? Bear in mind, an internet connection is ...
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1 answer
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Inter Device Expandable Network Protocol?

Currently I am working on a project where I need to install several peripheral devices in the network along with a master. This total system have some industrial application. I need to have the ...
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3 votes
1 answer
1k views

Generate hamming code-words with given minimum distance

My understanding of hamming code (adding this as it might help someone in future): Description: Hamming code is basically an extended parity check code. Message is divided into blocks, and multiple ...
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2 votes
1 answer
2k views

What is problem with NRZ and how manchester line coding handles out of sync tx and rx clocks.?

I am reading about physical layer of the OSI model. Specifically the different ways in which digital bits can be represented as voltage levels, among the multiple types are: NRZ. Manchester encoding. ...
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-2 votes
1 answer
300 views

What can i use an oscilloscope for in terms of networking [closed]

as someone who is just getting their feet wet in networking (going for a+ cert currently and would like to go further,) ive noticed that oscilloscopes can be used to monitor... seemingly any ...
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0 votes
1 answer
220 views

Raspberry connected to adhoc and wifi simultaneously [closed]

Currently I am working on a project where we have to connect multiple cameras to a Raspberry. Our idea is to buy multiple Raspberry PIs with a connected camera. These raspberries connect to a ...
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0 votes
1 answer
78 views

How to implement Ad Hoc on Radio Frequency node? [closed]

i want to implement RF based network as indicated in below figure Node is Basically Radio Frequency Transceiver i.e Si4432 interfaced with C8051 Micro controller . These nodes are simply Act as a ...
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1 vote
0 answers
108 views

XBee S2C DigiMesh Networking

I recently bought a Digi XBee S2C Development Kit. This is my first time with XBee radios and I'm working with DigiMesh as I will be using sleeping coordinators to make the entire network sleep. I ...
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1 vote
1 answer
597 views

Can we do source transformation for dependent sources? [closed]

In network analysis, during source transformation for dependent sources
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0 votes
2 answers
1k 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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2 votes
1 answer
285 views

Unshielded RJ45 connectors on SFTP Cat5e

I have "inherited" an old SFTP Cat5e cable connecting the basement of my house to the upper floor. There seems to be a break on some of the wires (6 and 7) so it won't even function at 100mbps. I ...
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0 votes
1 answer
194 views

Different phases on different components

Say I have a typical wiring in my room where in I have two computers (A and B). A is a ...
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1 vote
0 answers
85 views

Would forward error correction help?

I am working with a 433 Mhz transmitter for an arduino project. I found a Manchester encoding library on github(https://github.com/mchr3k/arduino-libs-manchester). It has checksums built in but the ...
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0 votes
1 answer
1k views

MCS 6 Transport Block size for 1 RB?

Edit: for some context I'm working on an LTE project and was wondering if anyone more knowledgeable than I would be able to answer this question. Given the first table, we can see the relationship ...
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1 vote
1 answer
2k views

What do pull-up and pull-down resistors do in an ethernet PHY?

I've noticed that most ethernet physical layers (i.e. the interface between the MAC/network and e.g. an RJ45 connector with magnetics) have pull-up or pull-down resistors on the TX and RX lines. For ...
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0 votes
2 answers
2k views

Where is ESP8266 TCP/IP stack defined?

I just installed Micropython on my ESP8266 and realized that TCP/IP works fine with it. This made me realize I don't know where it's defined - options that came to my head are: 1) in Micropython code, ...
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1 vote
1 answer
75 views

How can 100Base-T achieve 100 meter distance at 125Mhz clock?

I admit I have some large holes in my understanding of this topic, but it seems like you run into physical limitations of the speed of light. If the speed of electricity through copper is about 280,...
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