Telos Zephyr, User Manual

Page: 40 / 258

Section 3 ZEPHYR AT A GLANCE
40
FRONT PANEL
Display
LOCK SYNC
RECEIVE
C H A N N E L B
SEND
2
–30 –24 –18 –12 –6 0 LEVEL LINE –30 –24 –18 –12 –6 0
LIMIT
Audio Level Meters
The audio level LEDs provide a check on the send and receive audio.
The SEND audio level LED meters aid send level adjustment. Send audio should
be adjusted so that the green segments are illuminated, with the red segments flashing
occasionally. The 0 dB segment corresponds to the system clip point. However, even
this segment may illuminate without audible trouble owing to the efficacy of the
internal limiter, if engaged.
The RECEIVE audio level LEDs indicate that audio is being received and decoded. They
are calibrated to match the send audio level LEDs at the encoder.
Limit Indicators
The Zephyr has a send audio limiter which serves to keep the usual “digital nasties”
from happening when the send program signal grows instantaneously too large. This is
a very fast and very “tight” limiter which does not assert itself during times of normal
audio level. The idea here is to keep the system out of trouble when, say, a sports
announcer, on remote, gets excited.
With a sine tone, the limiter engages at 15 dB above the nominal operating value, but
since the limiter activity depends upon the peak- to- average ratio of the program
material, it may appear to operate at somewhat less than 15 dB above nominal with
some kinds of audio as input.
The LIMIT LEDs should only illuminate occasionally. If they are on consistently, reduce
the send level.
Status LEDs
The SYNC LED near the SEND meter indicates “all’s well” with the system. The software
must be loaded, up and running, and internal system clocks properly functioning. (This
LED may not always be on when you are not using the internal ISDN interface. In this
case, it reflects the status of the external interface, as well as the Zephyr’s internal
condition. Refer to manual section 6 (Non- ISDN Networks.)
The LOCK LED near the RECEIVE meter illuminates when the receive decoder has
locked on to a valid coded signal from a unit who’s transmit mode set to correspond to
your receive mode.