Aes/Ebu Error; Remote Control; Location Of; Optimal Control - Orban 8218 Operating Manual

INTRODUCTION
Orban
Model 8218
The
gain
is
scaled so that
0.8V peak-to-peak at
the subcarrier input
produces
10%
subcarrier
injection
with reference to
100%
deviation
of the
FM
carrier.
A
19kHz
TTL-level square
wave
is
available
on
pin
24
of the
remote
interface,
located
on
the rear panel
of the unit.
This provides a
means
for
synchronizing an
external subcarrier
generator,
like
an
RDS
(Radio
Data Systems) subcarrier, to
the
19kHz
pilot tone.
AES/EBU
Error
Alarm
Function
An
"alarm" function
monitors the
received
AES/EBU
bitstream, indicating
if
there
is
a
parity error,
a bi-phase coding violation,
a receiver
PLL
not locked condition or
if
the
AES
transmitter set
the validity
bit.
Upon
detection
of
any of these
errors,
the
8218
continues to
look for
subsequent error activity
within the
next
250msec.
If
the flag
remains active within
that
time frame, a
+15V
strobe
is
sent to the
8218 rear
panel
Remote
Connector
pin
10,
and
the front panel "digital"
LED
flashes at
a
4
per
second
rate (to differentiate this
from
the
2
per second
rate
indicating
a loss
of
digital
input, e.g.
PLL
not locked, forcing the unit to
switch
to
use the
analog input).
The
+15V
strobe
and flashing
LED
remain
for
4
seconds
following
the last
detection
of an error condition, after
which
pin
10 goes back
to
its
normal
-15V
state,
and the "digital"
LED
reverts to
its
previous
state.
The
± 15V
strobe
is
capable
of delivering
10mA.
Remote
Control Interface
The Remote
Control Interface
is
a
set
of seven
optically-isolated inputs
and two
outputs
on
a
DB-25 connector
that
can be activated
by
5-12VDC
or
AC
50/60Hz
signals.
The
seven
inputs
allow
you
to select
between
various functions of the
8218:
•
Analog/Digital Input.
• Pre-Emphasis On/Off.
•
Operation
Mode
(Stereo,
Mono
From
Left,
or
Mono
From
Right).
The two
outputs
on
the
Remote
Control
Interface are a Digital Pilot
Reference Output Clock
and
the
AES/EBU
error
alarm
function.
Location of
8218
Optimal Control of
Peak
Modulation Levels
The
audio processing circuitry in
most
modem
audio processors produces a
signal that
is
pre-emphasized to either the
50gs or 75gs standard
curve,
is
precisely
and
absolutely
high
frequency-controlled
and
peak-controlled
to
prevent over-modulation,
and
is
filtered at
15kHz
to
prevent distortion
caused
by
aliasing-related
non-linear crosstalk in
FM
stereo
systems.