![]() ![]() Farnsworth settings are used for morse training by sending morse characters at a higher speed (say 10 wpm) while the character spacing is around 5 or 8 wpm. Press the Fansworth switch to set the Farnsworth value. The default value of 201 represents a tone frequency of around 400Hz. The filter value is displayed on the LCD as T=xxx where xxx is the filter value. The function will sweep up and down until a lock is made on the incoming tone frequency. Press the SWEEP (Right) switch to tune the digital pot attached to the LM567 tone decoder. Increase the value on noisy signals to improve readability. The larger the value the greater the delay. The filter introduces a delay when reading the morse input in order to reduce the effect of noise pulses on the input signal.The filter value is displayed on the LCD as Fl=x where x is the filter value from 0 to 8. Press the FILTER (Left) switch to adjust the noise filter value. INSTRUCTIONS FOR USE OF THE MORSE DECODER So if you are in a situation where after a while you cannot seem to correctly decode morse, simply press the sweep button which will retune the decoder input frequency to the current tone value AND reset the timers and default values. To correct this I simply reset these values whenever the SWEEP button is pressed. I found that the values of the 'startUpTime' and 'startDownTime' variables became very large whenever there was a delay in receiving any morse input. Budd also indicated the reset should be used occasionally. The only way to fix it was to press the reset button. This was most apparent when there had been no morse input for a while. When running the original WB7FHC version it used to get itself into a mode where it would no longer decode morse. Ive also removed the sidetone and speaker connection as I prefer a softer sine-wave side tone which I can generate externally. ![]() These include a 'live' adjustable farnsworth setting, a much faster sweep tuning function by reducing the tuning range, and changes to the general operation and LCD layout. I have made some software changes to suit my circumstances. The CW decoder uses the same basic LM567 circuit designed by Budd Churchward WB7FHC which is connected to an Arduino Nano. If you've read this far, you may be interested in the older version of this tool which does not attempt to adapt to the sound and also includes more diagnostic information.A Morse Code Decoder based on WB7FHC's Simple Morse Code Decoder. The volume threshold is the value (0-255) which the measured volume in the analysed frequency must exceed to be counted as a dit or dah. The volume filter (which uses dB) discards very quiet (very negative) or very loud (close to zero) sounds and scales the size of the remaining data. There are three parameters which are not automatic: the minimum and maximum volume filter settings and the volume threshold setting. The frequency can only be certain values and the closest allowed value will be chosen. If you want to fix the frequency or speed then click on the "Manual" checkboxes and type in your chosen values. In fully automatic mode, the decoder selects the loudest frequency and adjusts the Morse code speed to fit the data. From these timings it determines if something is a dit, dah, or a sort of space and then converts it into a letter shown in the message box. If the volume in the chosen frequency is louder than the "Volume threshold" then it is treated as being part of a dit or dah, and otherwise it records a gap (this is shown in the lower graph that looks like a barcode). The spectrogram of the sound is shown in the main graph along with a pink region showing the frequency being analysed. The decoder will analyse sound coming from the microphone or from an audio file. ![]()
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