Godafoss Audio Spectrum Waterfall QRSS CW FSKCW 1.1

Godafoss offers an innovative visualization of the audio spectrum, allowing users to observe various slow transmission speed signals, including QRSS CW, DFCW, and FSKCW. The application supports sound acquisition through your device’s microphone placed near the audio output of your radio, or via a direct connection using an appropriate cable.

The interface features a frequency axis displayed to the right or bottom of the screen, depending on the waterfall's running direction. Users can easily navigate through the audio frequency range by sliding their finger across the screen in alignment with the frequency axis. Additionally, pinch and zoom functions enable fine-tuning of the frequency span, with a maximum range from 0 to 20 kHz.

For those who wish to avoid accidental changes to the frequency range, a Lock button can be activated, ensuring that panning and zooming do not alter the current settings.

Upon initial launch, Godafoss defaults to an FFT size of 4K with a Hanning window. Users can customize these settings by accessing the Setup button, which displays a control set. The first two sliders allow adjustment of minimum and maximum audio levels for waterfall colors—optimizing display aesthetics for specific signals. A blue background is typically preferred; thus, adjusting the minimum dB slider is recommended followed by configuring the maximum slider to represent the strongest signal, potentially setting it to red or pink for visual clarity.

The FFT size impacts frequency resolution, with larger values providing enhanced detail but slower updates, potentially affecting the representation of rapid signals. The window type function is crucial for refining data analysis, as it minimizes "leakage" from non-periodic signals that can distort frequency readings. Users may experiment with several available window types:

• Rectangular
• Hanning
• Hamming
• Tukey
• Cosine
• Lanczos
• Blackman

The Speedup feature allows multiple FFTs to be conducted on the same audio samples with slight time shifts. This is particularly advantageous when requiring larger FFT sizes while maintaining a quicker update rate on the waterfall. A speedup factor of 1 indicates no acceleration, while a factor of 10 executes ten FFTs for each data sample.

Users also have the option to change the waterfall's running direction—left, right, up, or down—to better suit their viewing preferences. It is essential to note that adjustments made to these settings will only influence newly received audio; previously displayed data retains its original parameters.

To capture a screenshot of the waterfall display, users can tap on it three times. A flash on the screen confirms that the image has been taken and saved to the Saved Photos album, allowing for easy sharing of received signals with others.