Orban OPTIMOD-FM 8500S, Руководство по эксплуатации

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OPTIMOD-FM DIGITAL INSTALLATION
2-11
AES3id Sync Input
The AES3id Sync Input accepts AES3id and AES11id signals on a 75
Ω
BNC connector.
This input can also be used as an AES3id audio input. One important application is
using it in conjunction with the second AES3 output to loop-through an Arbitron®
or similar ratings encoder having a digital input and output. In this case, the 8500S’s
BNC input drives the 8500S’s stereo encoder and the second AES3 output is config-
ured to emit the
FM or FM+D
ELAY
peak-limited audio, which drive the rating en-
coder.
Grounding
Very often, grounding is approached in a “hit or miss” manner. However, with care
it is possible to wire an audio studio so that it provides maximum protection from
power faults and is free from ground loops (which induce hum and can cause oscilla-
tion).
In an ideal system:
•
All units in the system should have balanced inputs. In a modern system with
low output impedances and high input impedances, a balanced input will pro-
vide common-mode rejection and prevent ground loops — regardless of
whether it is driven from a balanced or unbalanced source.
•
The 8500S has balanced inputs. Its subcarrier inputs are unbalanced, but fre-
quency response is rolled off at low frequencies to reject hum.
•
All equipment circuit grounds must be connected to each other; all equipment
chassis grounds must be connected together.
•
In a low RF field, cable shields should be connected at one end only — prefera-
bly the source (output) end.
•
In a high RF field, audio cable shields should be connected to a solid earth
ground at both ends to achieve best shielding against RFI.
•
Whenever coaxial cable is used, shields are automatically grounded at both ends
through the terminating BNC connectors.
Power Ground
•
Ground the 8500S chassis through the third wire in the power cord. Proper
grounding techniques never leave equipment chassis unconnected to
power/earth ground. A proper power ground is essential for safe operation. Lift-
ing a chassis from power ground creates a potential safety hazard.