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fsphil / hacktv

Analogue TV transmitter for the HackRF
GNU General Public License v3.0
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Fix levels of colourburst and modulated chroma. #40

Closed atsampson closed 4 years ago

atsampson commented 4 years ago

hacktv's PAL waveform for test:colourbars (100% bars) currently looks like this:

hacktv-waveform

The colourburst and modulated chroma should be twice the amplitude shown there -- compare with the 100% bars waveform on Pembers' site.

Fixing this works OK for PAL, but for NTSC the output now clips (because the maximum excursion is a bit bigger and there's not quite enough headroom) - I'm not sure whether it'd be better to reduce the level a bit in the vid_config_ts, or to make the test code generate 75% bars...

fsphil commented 4 years ago

Thanks. I've confirmed the error and merged your fix.

I'm fairly sure my NTSC code is not correct. I believe the peak voltage should be 0.933912v which shouldn't clip.