General description
The PSK decoder supports both PSK31 and QPSK (with soft bit Viterbi decoder) modes. The decoder uses the most modern digital PLL synchronization technology for bit synchronization and a neural network for detection. It prints PSK varicode characters on the screen. It searches the CW transmission in the range of the given frequency boundaries. Also you can set the decoded frequency by doubleclicking mouse on the wanted frequency position.
When PSK transmission has been detected in some frequency in the given range, the decoder will then lock itself to that frequency. When locked, the decoder draws the bolded blue line on the spectrum display on the currently locked frequency. If the decoder is not locked, then the blue line is not shown as bolded. After locking the frequency, the decoder starts to estimate the keying parameters of the transmission. When all the parameters have been estimated then the decoder starts to print characters on the screen.
In the locked state, the carrier frequency is automatically monitored within the given frequency boundaries. If the carrier frequency changes, then the decoder moves to the new frequency. If 'Lock' is pressed in the user interface, then the decoder will not automatically change it's frequency. ‘Reset’ resets the decoder and the received text can be saved using ‘Save’.
Configuration
Pressing the 'Config' button opens the following configuration dialog.
Parameters
Detection mode
The mode (BPSK =PSK31) or QPSK is selected.
Tone scan area
The scanned frequency range is given with two values low and high. The PSK transmission is searched only within this frequency window. In most cases it is useful to search first transmission visually using the spectrogram, FFT and 3DFFT displays and then define the scan area for the PSK decoder.
FFT
The FFT button opens and closes the power spectrum window. You can for example close the power spectrum window when the decoder has locked into correct frequency in order to get more space for text window
Save
The save button opens the log file control dialog, which is used to open or close a log file. The detector text window can be also saved into file or sent into socket.
Lock
The lock button locks or unlocks the decoder frequency. Decoders have the automatic frequency scanning feature. Push the lock button when you want to lock decoder into selected frequency. Push Un-Lock button when you want to release the frequency locking.
Reset
The reset button resets the decoder and clears the text window.
