Most commonly a type of transmission line that consists of two individual wires twisted together. Its differential nature attenuates common-mode interference present in the environment, which is useful in the transfer of differential signals (even low-frequency ones). It is commonly used for differential digital communication protocols such as ethernet.
Questions tagged [twisted-pair]
89 questions
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Why were coax cables used for networking?
Often, if older standards become obsolete, it's because they are superseded by newer technologies. In the past networking was done using coax, instead of the twisted pair used today. Why did they use the more expensive coax? It doesn't look like the…
The Resistance
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Correct place to attach shields for twisted pairs
I have two PCBs connected by a cable containing 5 sub-cables:
6v power through a custom made coaxial cable (similar to that found on laptop power supplies).
2x 100mbps LVDS through 100ohm impedance screened twisted pair.
2x 1mbps CAN through the…
Rocketmagnet
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Twisted Pair Twist Rates
What are the mathematics behind twisted pair cabling? I know that the twists are there to help eliminate cross talk and interference, but I want to know about the math of how they find the specific twist rates.
Is it just experimentation ("Oh looks,…
user2859
16
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Terminating shielded/screened twisted pair correctly
Theoretically, I can't see a problem if the twisted pair has an end of cable termination that is: -
A single resistor (R) that matches the characteristic impedance of the cable placed across the two ends of the pair or,
Two resistors…
Andy aka
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What if there are an odd number of twists in a twisted pair cable?
I am not an electrician, or a student of the field. I am a Network Engineer with a curiosity bug and that has recently taken me to exploring cabling and Twisted Pair specifically. I say this to plead that the answers be 'dumbed down' so that I can…
Eddie
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Why do UTP pairs need different pitches?
Why do unshielded twisted pair cables need a different pitch/twist rate for every pair of wires in a cable? Most of my reading on UTP says that the pairs in a cable must have different pitch or else the benefits of UTP will be lost which is the…
hontou_
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Is there any benefit to using twisted pair for short-distance I2C?
I know twisted pairs are important for differential signals, which I2C is not. I also know I2C is not intended to be used over long wires. However, I made a design where I need to use a cable to connect two devices over I2C. The expected length is…
Arthur Tarasov
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When should twisted pair wires be used?
I know several applications where twisted pairs are used and why they are used in those applications, but I would like to know more about the advantages and disadvantages of using twisted pair wires so I can choose appropriately based on what I am…
Hari
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Why didn't 1000BASE-TX gain more popularity than 1000BASE-T?
1000BASE-T uses all 8 wires in a twisted pair to both RX and TX at the same time. It does it using (what seems to me) a complicated process known as echo cancellation. Details here.
1000BASE-TX dedicates two pairs (four wires) in a Twisted Pair to…
Eddie
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Why are coaxial cables typically faster/longer than twisted pairs?
I'm having trouble understand why coaxial cables tend to have higher bandwidth compared to twisted pairs. I couldn't find any source explaining why, they just mention the fact.
For instance:
"In comparisons between coax vs twisted pair, coaxial…
Essam
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Using twisted pair for supply
Is using twisted pair for the supply in a long cable a good idea?
The cable contains two twisted pairs; one twisted pair for CAN Bus, and the other twisted pair would be used for GND / Supply.
What would be the effects of using such a cable? Good…
SensorMan
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Does using twisted pair wiring make sense only for differential signalling?
I read that the twisted-cable wiring is used for eliminating the common mode noise. As far as I know, in differential signalling the two wires carry their mirrored images so any common mode noise like EMI will cancel at the differential amplifier…
user1245
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Attaching Cat7 (S/FTP) Cable to PCB
We are planning on using Cat7A twisted pair cable for an application with which high bandwidth (~800MHz) analogue signals are being transferred over around about 3 metres.
At the moment the cable uses ARJ45 connectors (they are premade cables), so…
Tom Carpenter
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Why don't oscilloscope probes use twisted pairs?
I was reading online about how Ethernet cables use twisted pairs instead of coaxial cables because it's better in some way. Some websites say that twisted pairs cost less, can carry higher frequencies, and filter out noise, cross talk, interference,…
loadingnow
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PCB equivalent of wire twisting
I've a PCB with quite some electronics including a few motor drivers (30V, 100kHz PWM), and a few brushed DC motors 1 meter further away. These motors each have a quadrature encoder, so next to their 2 motor leads, they also require wiring for a 5V…
Huisman
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