Analog Left/Right Input/Output; Stereo Analog Baseband Composite Output; Subcarriers - Orban OPTIMOD-FM 5500 Operation Manual

OPTIMOD-FM DIGITAL
When the 5500 is operated as a stand-alone stereo encoder, the analog and digital
outputs emit the same signal that drives the 5500's stereo encoder DSP block. This
signal may be lowpass filtered and/or protection-limited, depending on control set-
tings in the active preset. The level, de-emphasis, and other parameters of these
outputs are set in System Setup and are the same regardless of whether the 5500 is
operating in its audio processor or stand-alone stereo encoder modes.

Analog Left/Right Input/Output

The left and right analog inputs are on XLR-type female connectors on the rear
panel. Input impedance is greater than 10k; balanced and floating. Inputs can ac-
commodate up to +27 dBu (0 dBu = 0.775Vrms).
The left and right analog outputs are on XLR-type male connectors on the rear
panel. Output impedance is 50; balanced and floating. The outputs can drive 600
or higher impedances, balanced or unbalanced. The peak output level is adjustable
from –6 dBu to +24 dBu.
Level control of the analog inputs and outputs is accomplished via software control
through System Setup (see step 3 on page 2-29 and step 8 on page 2-32) or through
PC Remote.

Stereo Analog Baseband Composite Output

The stereo encoder has two unbalanced analog baseband outputs on two BNC con-
nectors on the rear panel. Each output can be strapped for or 7source imped-
ance and can drive up to 16dBu (±13.82V peak) into 7in parallel with up to
0.047F (100ft/30m of RG-59/U cable) before any significant audible performance
degradation occurs.
See the footnote on page 1-14 and refer to Figure 2-3 on page 2-8.
Independent level control of each output is available via software (see step 6 on
page 2-31.

Subcarriers

The stereo encoder has two unbalanced 60subcarrier (SCA) inputs with rear-
panel BNC connectors to accept any subcarrier at or above 23 kHz. The subcarriers
are mixed into each composite output and their level is not affected by the compos-
ite level control for that output. The 5500 does not digitize subcarriers; the mixing
occurs after D/A conversion and is analog.
Subcarrier inputs sum into the composite baseband outputs. Rear-panel accessible
PC-board-mounted trim pots allow the user to adjust the sensitivities of the two SCA
inputs from <100 mV p-p to >10 V p-p to produce 10% injection with respect to
100% modulation = 4 V p-p at the 5500's composite outputs (the factory setting is 4
1-9
INTRODUCTION