สายเคเบิลดิจิทัลกับอนาล็อก: ทำไมถึงสำคัญ

## Digital Signals

Digital cables (HDMI, DisplayPort, USB, Ethernet) transmit data as 1s and 0s. The signal either works perfectly or doesn't work at all — there's no 'slightly bad' digital signal (the 'digital cliff').

**Digital cables**: HDMI, DisplayPort, USB, Thunderbolt, Ethernet, TOSLINK, S/PDIF

## Analog Signals

Analog cables (VGA, 3.5mm audio, RCA) transmit continuous electrical waves. Signal quality degrades gradually with distance, interference, and cable quality.

**Analog cables**: VGA, component video, composite video, 3.5mm audio, RCA, XLR

## Why Adapters Get Complicated

Converting between digital and analog requires an **active adapter** with a chip inside. These are more expensive and can introduce latency.

- HDMI → VGA: Active adapter needed (digital → analog)
- DisplayPort → VGA: Active adapter needed
- HDMI → DisplayPort: Active adapter (different digital protocols)
- DisplayPort → HDMI: Passive adapter works (DP has HDMI compatibility mode)

## The Quality Question

For digital: an expensive cable doesn't give better picture quality than a cheap one, as long as both meet the spec. For analog: cable quality genuinely matters.