Analog BTSC licensing program (early 1980s – 2004)
The dbx-tv companding noise reduction system used in BTSC was covered by several fundamental patents, most prominently US Patent 4,539,526 ("Adaptive Signal Weighting System"). These patents and the corresponding dbx trademark were licensed to over one hundred equipment makers (mostly TV and VCR makers) over the life of the patents. Although ownership changed several times after its introduction in 1984, the portfolio, technology, and dbx-tv brand have been solely in THAT's hands since THAT purchased them in 1994.
We retired the original analog licensing program in January of 2004 when the above-mentioned patent expired. Since that time, all analog implementations of dbx-tv's BTSC noise reduction system have been free of any licensing requirements. Because it was based on analog technology, this IP portfolio never included any IP "cores" as modern DSP offerings do: it comprised patents, circuit design know-how, and rights to the dbx trademark only. As well, dbx, Inc.'s, as well as THAT's sole focus was on licensing equipment makers.