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- Newsgroups: sci.electronics
- Path: sparky!uunet!infonode!ingr!b30!catbyte!medin
- From: medin@catbyte.b30.ingr.com (Dave Medin)
- Subject: Re: Dolby B/C? (A??)
- Message-ID: <1992Jul29.194939.15747@b30.ingr.com>
- Sender: medin@catbyte (Dave Medin)
- Reply-To: medin@catbyte.b30.ingr.com
- Organization: Intergraph Corporation, Huntsville AL
- References: <1992Jul22.130639.933@wpi.WPI.EDU> <1992Jul23.113150.7221@ohm.york.ac.uk> <1992Jul28.113002.607@cmkrnl.com>
- Date: Wed, 29 Jul 1992 19:49:39 GMT
- Lines: 29
-
- In article <1992Jul28.113002.607@cmkrnl.com>, jeh@cmkrnl.com writes:
-
- |> Full-bandwidth companders are fairly old hat. What Dolby A nr did that was new
- |> was to derive four different control signals from four different audio bands,
- |> and use them to control companders which operate only in those respective
- |> bands. The result was a marked reduction in "pumping" and "breathing" and
- |> "noise tails" which were associated with simple full-bandwidth companders.
- |>
- |> dbx, incidentally, is a sort of a cross-breed. Its compander operates on the
- |> entire audio band, but its control signal is derived not from a full-bandwidth
- |> "level" but from a proprietary filter network that samples just a few key
- |> frequencies.
-
- Close. dbx has simultaneous wideband AND multiband companding. The bands and
- the companding algorithm depend on the dbx type (I, II, or III, while
- MTS TV uses a combination of the above along with fixed EQ). The published
- algorithms exist in dbx's patent filings.
-
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