Morse Code with Light Signals (Flashlight & Mirror)

Visual Morse Code Signaling

Morse code is not limited to radio or telegraph — it can be transmitted using any medium that can produce two distinguishable states. Visual signaling with light is one of the most practical alternatives.

Flashlight Signaling

Using a flashlight to send Morse code:

Dot:  Quick flash (about 1 second)
Dash: Long flash (about 3 seconds)
Gap between symbols: 1 second darkness
Gap between letters: 3 seconds darkness
Gap between words: 7 seconds darkness

Signal Lamp (Aldis Lamp)

A signal lamp is a focused light with a shutter or trigger:

• Used extensively by navies until the late 20th century
• Still carried on military vessels as a backup communication method
• Effective range: 5–10 miles in clear conditions
• Advantage: Silent, does not emit radio waves (undetectable by SIGINT)

Mirror Signaling (Heliograph)

Using a mirror to reflect sunlight:

• Long flash: Hold the reflection on target for 3 counts
• Short flash: Quick flash for 1 count
• Effective range in clear conditions: 30+ miles with a proper signal mirror
• Used by military forces from the 1800s through World War II

Emergency Survival Use

In a survival situation, you can signal SOS (... --- ...) using:

1. Flashlight: Three short flashes, three long flashes, three short flashes
2. Car headlights: Same pattern with high beams
3. Mirror: Reflect sunlight in the same pattern toward rescuers
4. Fire: Alternating blocking and unblocking a fire with a blanket

International Signal of Distress

Flashing SOS with any light source is recognized internationally as a distress signal. Mountain rescue teams, coast guards, and search and rescue teams are trained to watch for this pattern.