Crosstalk is Just Like Music Leaking from Someone's Earphones on a Crowded Train.

An electromagnetic field occurs around a copper cable when electric current flows 

　↓

The electromagnetic field affects the other copper cables 

　↓

Unintended signals ride on the copper cables

　→ This is Crosstalk

In a crowded train, you may have experienced music leaking from someone else's earphones. 

That leaked sound mixes with the music you are listening.

　→ This is Crosstalk image

・Decline in communication speed

・Data corruption

・Unstable connection

・Rise in error rate

8 Copper cables interfere each other inside the same LAN cable 



┌─────────────────┐

│ ○ ○ ○ ○ ○ ○ ○ ○ │ ← 8 cables inside LAN cable 

└─────────────────┘

　　↑

This copper cable interfere each other in electromagnetic field

Feature：

・The most common Crosstalk

・Cannot be physically separated since the interference occurs inside the cable itself. 

・Twisted pair and shielding are the solusions

Other cables adjacent to a cable interfere each other 



Cable A ──────────────

Cable B ──────────────  ← Run side by side

　↑

These two cables interfere mutually

Feature：

・It tends to occur when cables are bundled or run side by side

・The interference will be greater when it run next to a power cable

・Physically separating the cables is the solution

When two copper cables are twisted ：



Copper cable A → Generates a clockwise electromagnetic field 

Copper cable B → Generates a counterclockwise electromagnetic field

    ↓

Each electromagnetic field cancels each other out

　↓

Leakage to outside decreases

Coarse twisting：

　→ Cancellation is weak 

　→ More leakage

　→ Huge interference（Frequent Crosstalk）



Fine twisting：

　→ Cancellation is strong

　→ Less leakage

　→ Minimal interfeernce（Less Crosstalk）

More Twists

　↓

Cancellation in electromagnetic field is stronger

　↓

Less Leakage

　↓

Signals are stable

　↓

High Speed

Every 2 copper cables are twisted together

　→ Cancellation in electromagnetic field

　→ Decline in interference



The more twisting, the greater the effect

　→ Higher CAT standard is more twisting

Over CAT6a：Whole cables are covered with shield

CAT7    ：Each pair are covered with individual shield



It can prevent leakage from inside electromagnetic field

Do not bundle each LAN cable

Do not run next to power cable 

　→ Physical separation can reduce interference

The cable covered with shield are used

　→ It blocks interference from outside sources

CAT5  → Coarse twisting

　→ More leakage・ More interference → Until 100Mbps



CAT5e → More twisting

　→ Less leakage・ Less interference → 1Gbps



CAT6  → More twisting + spine added to the center

　→ 10Gbps（Until 55m）



CAT6a → Add whole shield

　→ Prevent from interference from outside  → 10Gbps（100m）



CAT7  → Add individual shield to each pair

　→ No Internal Crosstalk → 10Gbps（100m）

Crosstalk ：The phenomenon of receiving electrical interference from copper cables



2 kinds of Crosstalk：

Internal Crosstalk

　→ Interference caused by copper cable in the same cable 

　→ Cannot separate physically

　→ Twisted pair・ Shield are the solution



External Crosstalk （Alien Crosstalk）

　→ Interference caused by adjacent cables

　→ Can separate physically

　→ Shield is also the solution



Core：

More Twists → Less Leakage → Less Crosstalk → High Speed

　→ This is the reason why higher CAT standards rise in speed

Internal Crosstalk  = Interference inside cable

　→ Solution : Twisted pair・ Shield



External Crosstalk  = Interference between cables

　→ Solution : Physical separation・ Shield



More Twists → Less Leakage → High Speed