Active vs. Passive: Solving the 'No Signal' Error

Digital signals degrade over distance. This is called attenuation.

The 3-Meter Rule

For high-bandwidth signals like HDMI 2.1 (48Gbps) or Thunderbolt 4, passive copper cables become unreliable after about 2-3 meters (6-9 ft). The resistance of the wire essentially 'blurs' the 1s and 0s.

Active Cables

An active cable contains a small chip (Redriver or Retimer) in the connector head. This chip draws power from the port to boost and reshape the signal.

Optical (Fiber) Cables

For runs over 50ft, you need AOC (Active Optical Cable). These convert electricity to light, transmit it over glass fiber, and convert it back. They are directional (Source vs Display ends matters!) and much more expensive.

Technical References

• IEEE 802.3: Ethernet Physical Layer signal definitions.