Module 01
Flashing light
Directional light signalling remains the most secure way to pass traffic between ships in company. It is silent, it cannot be detected beyond the beam, and it works when every circuit is down.
Lesson
Timing is the whole skill
Anyone can learn the characters in a weekend. What separates a signalman from a beginner is rhythm: every length below is measured in units of one dot.
1 unit
Dot (dit)
The base time unit. Every other length is measured against it.
3 units
Dash (dah)
Exactly three times the length of a dot — never a lazy two.
1 unit
Gap inside a letter
Between the dots and dashes of the same character.
3 units
Gap between letters
Silence equal to one dash separates characters.
7 units
Gap between words
A long pause so the receiver can break the text into words.
Reference
Alphabet and numerals
Tap any character to see and hear it.
Reference
Procedure signals
AA
Call sign / attention
Repeated to attract the attention of a station whose call sign is unknown.
K
Invitation to transmit
Sent by the receiving station: go ahead, I am ready to receive.
T
Answering sign
Single dash repeated to acknowledge each word as it is received.
AR
End of transmission
Ending sign. No reply is expected.
AS
Waiting sign
Stand by / wait, I am not ready.
BT
Break sign
Separates parts of a message, such as the text from the address.
C
Affirmative
Yes, or the preceding group is correct.
EEEEEEEE
Erase sign
Eight dots: my last group or word was in error, I will repeat it.
IMI
Repeat sign
Repeat, or I am repeating; also used as a question mark.
R
Received
I have received your last transmission correctly.
DE
From
Precedes the call sign of the transmitting station.
NO
Negative
No, or the preceding group is incorrect.