— 18 —
INTERNAL TONE GENERATOR
A built-in test tone generator (audio oscillator) may prove help-
ful in setting up the DAVID IV, or in verifying overall system
performance. Navigate to:
Setup / Oscillator
.
Pre and
Post Modes
Off
is the default selection for normal operation of the DAVID
IV. For testing, tones may be applied ahead of the processing
stages:
Pre
, or following all processing:
Post
.
Turn
the jog
wheel to position the brackets, and then
press
the jog wheel to
make the selection.
The test tone is a monaural source applied to both the left and
right channels.
Frequency
may be varied between 20Hz and
20kHz in 10Hz steps, and the
Level
of the test tone may be set
in 1dB steps between –60dBFS and 0dBFS.
Program
Frequency
and
Level
by
turning
the jog wheel to set the
brackets around the
Frequency
or
Level
slider, then p
ush
the jog
wheel to enable that slider so that you can then
turn
the jog
wheel to dial-in the desired frequency or level.
Frequency
pro-
gramming has ‘ballistic acceleration,’ meaning that the faster
you turn the jog wheel the more steps you get per revolution.
A Brief Note
on DAVID IV
Gain Structure
A –20dB, 400Hz test tone applied at the
input
to the processing
stages:
Pre
will bring the AGC to 0dB (unity) gain. –20dB is
the nominal internal “zero-VU” reference level at this point and
refers to the program’s
average
level.
Gain associated with normal processing action is expected to
drive the processor to full 0dB or 100%-modulation output.
Thus when this same –20dB tone is applied
after
processing:
Post
, it drives the composite/MPX output only to the 10%
point on the
MPX OUTPUT
meter, and to –20dB on the
L
and
R
OUTPUT
meters. Readjust
Level
to reach a desired output con-
dition.
SELECTING THE INPUT
The DAVID IV has both an AES (stereo) digital input and indi-
vidual left/right analog inputs. Either set can serve as the pro-
gram input to the unit. Characteristics of these inputs are dis-
cussed in the Specifications (Page 7) and in Section II (Page 12).
Summary of Contents for 719
Page 1: ...DAVID IV FM Audio Broadcast Processor Installation User Guide www inovonicsbroadcast com ...
Page 2: ......
Page 4: ......
Page 70: ... 66 NOTES AND DOODLES ...