Morse Decoder decodes Morse code characters through the built-in microphone of your Android device.

Morse Decoder can be used by Ham Radio operators or anyone else
interested in decoding Morse code from a Radio or any other device.

Morse Decoder includes a “waterfall” to show a frequency spectrum of
about 50Hz to 2300Hz. A narrow band DSP filter can be set for the
frequency of the Morse code tones by tapping the waterfall. The DSP
filter is followed by an automatic gain control (AGC) to compensate for
changing signal strengths.

The detected signal will be shown as a graph and several algorithms will
then detect the speed of the Morse code and convert them into readable
text. Speeds of less than 4 Wpm (Words per Minute) to more than 50 Wpm
can be decoded.


Place your Android device against the speaker of the radio or the
device which transmit the Morse code. If there is a tone present the
waterfall will display a blue or white vertical line (As stronger the
signal as brighter the line) Slide the red rectangular on top of the
vertical line. Even though Morse Decoder uses a 200Hz wide AFC
(automatic frequency control) it is recommended to move the slider
always on top of the vertical line. It may take several initial
characters containing both dots and dashes before the WPM speed
estimation acquires the actual Wpm and decodes the characters correctly.

Lock Speed:

Morse Decoder will constantly determine the speed of the Morse signs.
In very long breaks it is possible that Morse Decoder will detect the
wrong speed. The next couple of characters could be decoded wrong. After
Morse Decoder detected the right speed it is recommended to push the
“lock speed” button. Morse Decoder will lock the speed and will not
attempt to change the decoding speed.

Some advice:

To improve the performance it is recommended to place the device
directly against the speaker of the radio or the device which transmit
the Morse code. Morse Decoder still decodes Morse code when the device
is not directly placed at the speaker but several effects like phase
interference due to echo’s or background noise can disturb the



Screen lock: Prevents the screen from turning off. CAUTION: this option consumes a lot of battery power.

Waterfall sensitivity: Some Android devices have
very sensitive built in microphones others are very deaf. The decoding
algorithm uses an AGC but the waterfall sensitivity can be adjusted in
the settings.


Amateur radio operator from Malaysia

Leave a Reply

Your email address will not be published. Required fields are marked *