BI4PYM https://github.com/BI4PYM/UniHELL I developed a Chinese character Hell modulator based on a 14x14-point font library, which outputs 16-bit PCM WAV. It allows for custom Unicode (not fully comprehensive) text content and audio frequencies, and uses the standard FELD HELL mode for demodulation. Because the filter code was not working, it was necessary to manually apply a band-pass filter at 250 or 300 Hz using audio editing software or other audio filters. The unfiltered signal should not be transmitted via radio. The Hellschreiber mode exhibits strong anti-Doppler performance and can be used for communication on linear satellites. The font color becomes lighter because the amplitude changes during the Doppler simulation, and this has nothing to do with frequency shift. Also, who understands Python's band-pass filtering? Please provide some suggestions. The examples I found online don't work; they don't produce any errors, but there is no filtering effect.
BG2TFM BI4PYM Are you using `scipy.signal` for filtering? If you have a specific problem, please share it so I can help.
BI4PYM Now that simple keying has been implemented, the bandwidth requirements are smaller, and there's no issue with excessive bandwidth. This allows for transmission to the air. Bandwidth comparison: "hell" in English, referring to fldigi UniHELL's Chinese "hell" Demonstration of results If you find the boundary unclear, you can change `fltn = 0.5` in the code to `0.4` or `0.2`. The smaller the value, the clearer the boundary and the larger the bandwidth.
BG2KAJ It would be great if we could create a GUI and then link it to hamlib, which would allow us to release them.
BI4PYM BG2TFM The filtering issue has now been largely resolved, and I will explore Python filters further in the future.
BG2TFM BI4PYM Oh, I just saw this is an old post. If you have any questions, please feel free to post them here for discussion.
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