December 21, 2014
I'm trying to understand what the difference is between the Leary Bright patent http://www.google.com/patents/US7589272 and what is described in the book for hard sync.
From the book:
1. Output is always from the slave oscillator.
2. Whenever master oscillator resets, it will trigger the slave oscillator to reset. (to 0)
3. And hence you have a interesting waveform in the slave oscillator.
After briefly looking through the Leary Bright, it seems that the difference is in Fig 9.
Where the slave oscillator is not reset to 0, but to a predetermined value. (0.5 and 0.8 i nthe figures)
But, how does this reduce the aliasing?
Or if I missed something, what is it?
January 29, 2017
The description in the book for hard-sync is the ordinary version. The Leary/Bright patent extends the definition to include resets to non-zero values, but that general definition is not what the patent is about.
Instead, it shows that when doing hard-sync, points around the discontinuities will have to undergo multiple BLEP corrections. The block diagram shows how they accomplish this, but the way they are storing the BLEP table points is somewhat different. It is really a matter of figuring out how to do the multiple BLEP corrections.
The HS output I show in the Challenges section was from my own hard sync BLEP, but I was only correcting points once. This caused the oscillator to fail for high fundamental frequencies, high slave frequencies, or both. Andy Leary at Korg was the one who caught the error when he was proofreading that chapter, and I decided to make it a Challenge instead.
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