Morse decoder

Added in firmware version v1.1.0 and most recently improved in v1.2.0 - see firmware page for how to update.

WOLFWAVE incorporates a morse decoder. To access it, go to the main screen which shows the current audio spectrum and bandpass filter settings, then press the mode button to cycle between bandpass filter, bandstop filter, and morse decoder mode.

On the left is the most recent decoded text. On the right is part of the audio spectrum, centred on the detection frequency.

Decoding and signal detection

The morse decoder is driven from the same CW signal detection as the signal LED and CW regeneration. The detection frequency is always in sync with the centre frequency of the bandpass filter - changing detection frequency changes bandpass centre frequency and vice versa. This allows you to go straight from narrowing in on a signal using bandpass, to decoding it.

In the morse decoder screen, turn the multi use knob to adjust the detection frequency. The detection frequency is shown as a dashed line on the spectrum and as text in the bottom right corner. The detection threshold can be set in the menu.

Morse decoding is active when the morse decoder screen is visible, and for 30 seconds afterwards. This means that decoding will start when the mode button is pressed to switch to the morse decoder screen, and will continue happening in the background for a short time if, for example, you briefly access the menu to change some settings.

Scrollback

The decoded text can be scrolled, so that recent decoded text can be viewed even after it has disappeared off the screen.

Press the multi use knob to switch between adjusting the frequency and scrolling. To stop scrollback and go back to tracking the most recent text, scroll down to the most recent text, then scroll down further until "Auto scrolling" is displayed again.

Up to the last 200 characters will be stored. The oldest line of text will be trimmed whenever this limit is exceeded. While in scrollback mode, decoding will continue for up to another 100 characters, with no trimming of old text. Decoding will then be paused until you exit the scrollback.

Additional settings

The following settings are adjustable in the "Morse decoder" submenu:

• Signal threshold. If noise is being falsely detected as a signal, increase this to make detection less sensitive. This is shared with CW regeneration and appears in both submenus.
• Min and max speed. This is the expected range of morse code speeds in words per minute - the speed will be auto detected within this range. The default range of 5-40 wpm should be fine for receiving most transmissions, but may need adjusting for particularly fast or slow morse code. If the speed is within the current range but is not correctly detected, try adjusting the range to exclude the incorrect speed estimates. The speed determines what lengths of on and off pulses correspond to dots, dashes, inter-character and inter-word spaces, so if the speed estimate is too far out then the decoded text will be wrong.