Oscillator; Metering - Apogee AD-1000 Operating Manual

OSC Position
OSC selects a built in 1kHz digital oscillator calibrated to ± 0.01 dB with internal switch selectable output lev-
els for accurate headroom settings. When selecting OSC, the oscillator is selected and output on the corre-
sponding digital outputs. This is used primarily for headroom alignment and testing. The output level can be
selected by setting DIP switches located on the top of the AD-1000. The digital oscillator is set at 15dB below
full scale as a default. These switches can be changed by using a small screwdriver. The table below lists the
available test tone levels and the corresponding switch settings. When in OSC, a front panel LED will light indi-
cating the level of the OSC output as a reminder corresponding to the level that is set by the DIP switches.
Below is a diagram of the switch settings that adjust these and other secondary functions. This is duplicated on
top of the AD-1000 for convenience.
Level Below dB Full Scale
20
18
16
15
14
12
0
Audio Black*
*Audio Black is defined as a signal that contains clock data but no audio data (0 bits).

Metering

The front panel metering LED's indicate when the AD-1000 input signals are peaking in a comfortable range.
They are designed to be used in conjunction with the meters of the host system such as a DAT recorder, work-
station, etc.
The GREEN "–12" LED indication for each channel may be customized. The –12 labeling is nominal because
the threshold of this LED is tied to the digital oscillator level and can be varied from –20 to –12 below 0dBfs.
This is done by adjusting various switches on the top of the AD-1000.
The AMBER "–2 /SL" LED indicates when the input signal is 2 dB below full scale digital out. When Soft Limit
is engaged, it will also flash when the Soft Limit Threshold has been exceeded.
The RED "OVER" LEDs illuminate when three consecutive digital "Over" samples are output. The AD-1000 also
includes a unique feature for precise input calibration delivering accuracy unavailable with normal digital bar
graph meters of DAT recorders and workstations. Only with digital meters costing as much as the AD-1000 itself
can you approach the accuracy of this system. In conjunction with the Digital Oscillator settings, the –12 LED
will flash quickly when a tone is connected to the analog inputs and is within 0.05 dB of the oscillator level set
on the programming DIP switches, located on the top panels of the AD-1000. (Section 5, page 31 has more
information regarding these switches and the procedure to complete the calibration of your system.)
AD-1000 Operating Manual
Switch 2 Switch 3
Off On
Off On
On Off
Off Off
On Off
On On
On On
Off Off
Page 21
Switch 4 LED Display
Off Left –12 (green)
On Left –2 (amber)
Off Left Over (red)
Off Right Over (red)
On Right –12 (amber)
Off Right –2 (green)
On All On
On All Off