RRE: [BC] Mono Expands on the FM Band

[DANA PUOPOLO]

Yes, this is quite true. The upper sideband is actually REcreated from the
lower one, but the (original) sidebands might not have been exactly the same.

Bob is correct; I have always found it necessary to composite clip AFTER a CAT
link rather then before one. Of course, since modern digital processors
generally have composite clippers built into them, putting one before a CAT
link can make for weird modulation problems, unless you first disable the
units' internal composite processing.

My biggest problem with them (CAT links) was the NE5532 opamp they 
use(d) to run the composite waveform through, even though much better opamps
were around at the time (and being used by companies such as Orban).

Finally, there was the CE that discovered the MSI CP803 composite clipper
years ago (when it first came out). His belief was that if one was good, then
TWO must........

You know the outcome, I'm sure!

-D


------ Original Message ------
Received: Wed, 18 Jan 2006 07:23:56 PM PST
From: Robert Orban <rorban at earthlink.net>
To: broadcast at radiolists.net
Subject: RRE: [BC] Mono Expands on the FM Band

At 02:37 PM 1/18/2006, you wrote:
>From: DANA PUOPOLO <dpuopolo at usa.net>
>Subject: RE: [BC] Mono Expands on the FM Band
>To: "Broadcasters' Mailing List" <broadcast at radiolists.net>
>Message-ID: <792kaRs2B0864S21.1137610381 at cmsweb21.cms.usa.net>
>Content-Type: text/plain; charset=ISO-8859-1
>
>This is how the CAT link works. They truncate the upper sideband, which then
>gives them (the) room to fit the sampled waveform within a T1. On decode,
they
>mirror the lower sideband to create the upper one .

The main disadvantage of this system is that it does not preserve the level 
control introduced by any composite limiting in the signal feeding the STL. 
Composite limiting introduces a Q component into the stereo subchannel 
(i.e, the sidebands are no longer mirror images of each other) that cannot 
be preserved when one only retains only the lower sideband; information is 
lost.

Bob Orban 



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