TELOS TWOX12 USER’S MANUAL
DETAILED CONFIGURATION & REFERENCE
CHAPTER 7 140
sound independent of drive level. Its “smart” response normalizes levels while
retaining the natural dynamics of the caller’s voice.
An important additional feature of this AGC is that it is cross-coupled to other
sections of the TWOx12 and can therefore reliably distinguish between caller audio
and hybrid leakage. This allows a more aggressive gain control for bringing up low-
level callers while still preserving excellent hybrid performance.
Noise Gate
Turning on the noise gate enables the built-in downward expander. The downward
expander reduces low level line noise when no caller audio is present. And reduces
low level leakage thereby improving hybrid performance. This function is cross-
coupled with the AGCs and the duplex system.
Digital Dynamic Equalizer
Telephone audio frequency response varies widely as many different factors can
effect it (we’ve measured the response on a number of calls and the results were
revealing). Consequently, some form of receive equalization is desirable. See section
7.3.1 for details on how to adjust the DDEQ system.
The Digital Dynamic EQ process used on the Telos is the most sophisticated
equalizer available in a telephone hybrid. All processing is performed in the digital
domain. The Receive EQ selection controls the type of equalization applied to the
receive telephone audio as follows:
!
Off
The caller audio is passed without modification. The Rcv EQ values (see below) are
ignored in this mode.
!
Fixed
This is a simple manual equalizer mode where EQ values selected for LF and HF are
applied constantly.
!
Adaptive (Digital Dynamic)
This is a three band dynamic equalizer. The proper values of high and low frequency
boost or cut is automatically determined and set. We’ve chosen frequency
breakpoints, time constants, and other characteristics to optimize the tonal quality of
varied telephone callers. The Rcv EQ values (see below) are ignored in this mode.
!
Fix + Adap:
The Digital Dynamic EQ uses the Rcv EQ values (see below) as “target levels”. This
allows you to customize the quality of the sound, but still get a consistent quality to
the audio from caller to caller. Otherwise, the functioning is the same as Adaptive.
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