MORSE2ASCII Tool: Decode Morse Signals into ASCII Instantly

MORSE2ASCII Tutorial: Build a Simple Morse-to-ASCII Converter

This tutorial walks you through building a simple Morse-to-ASCII converter: a program that reads Morse code (dots, dashes, and spaces) and outputs corresponding ASCII text. We’ll cover the Morse alphabet, parsing rules, a clear implementation in Python, and simple tests you can run and expand.

What you’ll build

• A function that converts a Morse string into human-readable ASCII.
• Support for letters A–Z, digits 0–9, basic punctuation (.,?‘/@&:;=+-_“!()$), and word separation.
• Robust handling of extra spaces and invalid sequences.

Morse basics (rules)

• Dot = .
• Dash = –
• Letters are sequences of dots/dashes separated by a single space.
• Words are separated by a slash (/) or by two or more spaces (we’ll treat “/” and double spaces as word separators).
• Unknown sequences map to a placeholder like “?” so you can spot decoding errors.

Morse table (subset)

• A: .-N: -. 0: —– . (period): .-.-.-
• B: -… O: — 1: .—- , (comma): –..–
• C: -.-. P: .–. 2: ..— ? (question): ..–..
• D: -.. Q: –.- 3: …– ’ (apostrophe): .—-.
• E: . R: .-. 4: ….- / (slash): -..-.
• F: ..-. S: … 5: ….. @: .–.-.
• G: –. T: – 6: -…. &: .-…
• H: …. U: ..- 7: –… : (colon): —…
• I: .. V: …- 8: —.. ; (semicolon): -.-.-.
• J: .— W: .– 9: —-. = (equals): -…-
• K: -.- X: -..- +: .-.-.
• L: .-.. Y: -.– -: -….- -M: – Z: –.. _: _ (not standard; map as needed)

(Use the full mapping in the code below.)

Python implementation

python
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# morse2ascii.py
MORSE_TO_ASCII = {
    ”.-”:“A”,”-…”:“B”,”-.-.”:“C”,”-..”:“D”,”.”:“E”,”..-.”:“F”,”–.”:“G”,”….”:“H”,
    ”..”:“I”,”.—”:“J”,”-.-”:“K”,”.-..”:“L”,”–”:“M”,”-.”:“N”,”—”:“O”,”.–.”:“P”,
    ”–.-”:“Q”,”.-.”:“R”,”…”:“S”,”-”:“T”,”..-”:“U”,”…-”:“V”,”.–”:“W”,”-..-”:“X”,
    ”-.–”:“Y”,”–..”:“Z”,
    ”—–”:“0”,”.—-”:“1”,”..—”:“2”,”…–”:“3”,”….-”:“4”,”…..”:“5”,
    ”-….”:“6”,”–…”:“7”,”—..”:“8”,”—-.”:“9”,
    ”.-.-.-”:”.”,”–..–”:”,”,”..–..”:”?”,”.—-.”:”‘”,”-..-.”:”/”,
    ”.–.-.”:”@”,”.-…”:”&”,”—…”:”:”,”-.-.-.”:”;”,”-…-”:”=”,
    ”.-.-.”:”+”,”-….-”:”-”,”.-..-.”:’“’,”-.–.-”:”(”, ”-.–.-”:”)”
}

def morse_to_ascii(morse_str, unknown=”?”):
    # Normalize separators: treat ‘/’ as word separator, compress multiple spaces
    morse_str = morse_str.strip()
    # Replace slashes with triple-space marker to ensure separation
    morse_str = morse_str.replace(”/”, ”   “)
    # Split into words on 3+ spaces
    words = [w for w in import(“re”).split(r”\s{3,}”, morse_str) if w != ””]
    decoded_words = []
    for w in words:
        letters = [l for l in w.split() if l != ””]
        decoded = []
        for sym in letters:
            decoded.append(MORSE_TO_ASCII.get(sym, unknown))
        decoded_words.append(””.join(decoded))
    return ” “.join(decoded_words)

if name == ”main“:
    examples = [
        ”… — …”,                     # SOS
        ”… — …   .- .-.”,           # “SOS AR”
        ”.- / -… / -.-.”,                # “A B C” using slashes
        ”… — … –..– .-.-.-”       # “SOS,.”
    ]
    for e in examples:
        print(e, ”=>”, morse_to_ascii(e))

How it works (brief)

• Normalize separators: slashes replaced with triple spaces so both “/” and multi-space separate words.
• Split on 3+ spaces to get words, split words on single spaces for letters.
• Lookup each Morse symbol in the dictionary; unknown symbols become “?”.

Testing

• Run the script with the examples included.
• Try edge cases: leading/trailing spaces, mixed separators, invalid symbols like “…-.-” (should return “?”).

Extensions you can add

• ASCII-to-Morse encoding function.
• Tolerant input parsing for noisy signals (e.g., accept “|” or “,” as separators).
• GUI or web UI, or a command-line flag for case-insensitive output.
• Support prosigns or procedural signals (e.g., SK, SOS special handling).

That’s all — a compact, testable Morse-to-ASCII converter you can extend for more features.