- - - Dash-Dash-Dash | Also known as Oscar in the NATO phonetic alphabet
O in Morse code is --- (dash-dash-dash).
O in Morse code is --- (three dashes). The center of SOS (... --- ...).
Hear full words containing O on our free Morse code translator
or browse the alphabet chart.
"Oh-oh-oh" (3 long).
O = - - -
ON = - - - - .
OK = - - - - . -
International Morse treats timing as part of the character. A dot lasts one time unit, a dash lasts three, the space between elements inside O is one unit, and the gap before the next letter is three units. When you hear --- in a word, you are hearing one rhythm — not counting individual beeps. The official character set and ratios are defined in ITU-R M.1677-1 and summarized for beginners on Wikipedia’s Morse code article.
Copy these into the Morse code translator to compare what you hear with what you read. Letters are separated by spaces; words use a slash.
O → - - -
ON → - - - - .
OK → - - - - . -
O (- - -) is often mixed up with letters that share dots, dashes, or rhythm. On the air, context and prosigns disambiguate, but learners should drill look-alikes side by side:
#, you usually have an extra space inside a letter or a symbol that is not ITU Morse.
Pattern: dash-dash-dash. Memory hook: "Oh-oh-oh" (3 long). Say the rhythm out loud while you tap it on a desk — muscle memory beats staring at a chart. Amateur operators often recommend hearing each letter at full speed with longer gaps (Farnsworth spacing); try the Learn preset on the translator, then move to Koch lessons or a shareable Koch practice session. The ARRL learning hub links licensing paths if you want on-air copy practice after the alphabet.
Accessible SVG for O: three dashes (---) as three long marks in sequence, labeled O.
O is three dashes in International Morse per ITU-R M.1677-1 ITU-R M.1677-1, famous as the center character of SOS (... --- ...). Wikipedia Wikipedia: Morse code notes O among dash-heavy letters requiring accurate length.
Each dash must be three units with one unit between; compressing gaps turns O into M plus stray dash.
Aviation voice uses Oscar for O per NATO phonetics Wikipedia: NATO phonetic alphabet. Morse O appears in on and ok during CW ragchews.
Do not confuse Oscar with the Oscar maritime flag signaling man overboard; phonetics only spell letters.
ARRL learning pages ARRL: Learning Morse Code teach O alongside S because SOS combines both rhythms. Modern distress uses voice and digital alerts, yet operators study O for heritage and exam random groups.
Copy O within GO and NO to hear medial three-dash characters.
Coastal stations logged O-rich traffic in weather bulletins; ITU preserved O’s pattern in recommendation updates. Museum exhibits demonstrate SOS with labeled center O.
Primary sources on early wireless distress distinguish procedural SOS from plain alphabet O inside words.
Drill O (---) versus M (--) by anticipating a third dash. If dots appear, you are copying SOS fragments or S, not isolated O. Send O-M-G triads focusing on dash count.
Fatigued senders may shorten the third dash; listen through the full element before writing.
Oscar phonetic clarifies O on voice when spelling route names, while SOS teaching uses O as three dashes surrounded by S dot groups. Separate procedural SOS study from plain O inside words to avoid over-interpreting every three-dash sequence as distress. Wikipedia’s distress signal history pages document evolution from CQD to SOS; read them alongside ITU timing for responsible operating knowledge. ARRL emergency communications training emphasizes modern digital alerts yet retains Morse heritage modules where O timing appears. When copying GO or NO, mark O’s triple dash lightly until the word completes, preventing premature O versus M confusion.
Keyer users should verify that automatic character spacing inserts full three-unit gap after O before the next letter begins. Museum SOS demos often slow timing for visitors; adjust expectations when returning to on-air speeds.
Oscar phonetic during ground operations should not be confused with keyed triple-dash O inside English words on amateur CW nets. SOS heritage described on Wikipedia belongs in history study, not on-air tests, while still teaching O timing responsibly. Copy O in GO and NO slowly before attempting faster ragchew speeds on preferred HF segments.
Keyer users must confirm automatic spacing after third dash before next letter starts to avoid merging O with following dots.
Oscar phonetic for ground readbacks should not be confused with procedural SOS study where triple-dash O sits between S dot groups in historical documentation on Wikipedia. Copy O within short English words before attempting callsigns where O sits adjacent to other dash-heavy letters that mask the third long element. Automatic keyers need verified inter-letter delay after O so following dots are not absorbed into a phantom fourth dash during decoder analysis.
Confirm decoder inter-letter delay after triple-dash O before blaming sender timing when following S dots appear merged in contest log review exports.
Independent Morse tools · ITU-R M.1677-1 · No fabricated operator identity
These pages document a free browser translator and trainer. Timing follows International Morse (ITU-R M.1677-1). We do not claim an FCC callsign or Extra Class license for the site operator. Use the tools for practice; licensed instruction still matters for on-air work.
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