Transmission From Studio To Transmitter - Orban OPTIMOD-FM 8500S Operating Manual

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INTRODUCTION ORBAN MODEL 8500S
above the separation (approximately 20 dB) that starts to cause perceptible changes
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in the stereo image.
You will achieve a louder sound on the air, with better control of peak modulation,
than if you use most external stereo encoders.
An exception is Orban's 5518 stereo encoder, which does not add overshoot and
contains its own overshoot limiter and composite limiter equivalent to the one in
the 8500S when operated in its stand-alone stereo encoder mode.
The shorter the baseband cable from OPTIMOD-FM to exciter, the less likely that
ground loops or other noise problems will occur in the installation. If you require a
long cable run, you can use a Jensen JT-123-BMCF transformer 4 to break any ground
loops. This transformer will ordinarily cure even the most stubborn hum or noise
caused by the composite connection between OPTIMOD-FM and the exciter. For
connection instructions, please refer to the Orban CIT25 Composite Isolation Trans-
former schematic diagram, which is shown on page 12 of the CIT25 manual. This is
available from: ftp.orban.com/CIT25/CIT25 Instructions.pdf (Please note that Orban
no longer manufactures the CIT25, which used the Jensen transformer.)
If a separate stereo encoder must be used, feed the encoder directly from the
8500S's left and right analog or (preferably) digital outputs. If possible, bypass the
pre-emphasis network and the input low-pass filters in the encoder so that they
cannot introduce spurious peaks. Because of their special design, OPTIMOD-FM's
pre-emphasis network and low-pass filters perform the same functions while retain-
ing tight peak control.Studio-Transmitter Link

Transmission from Studio to Transmitter

There are five types of studio-transmitter links (STLs) in common use in broadcast
®
service: uncompressed digital, digital with lossy compression (like MPEG, Dolby , or
®
APT-x ), microwave, analog landline (telephone/post line), and audio subcarrier on a
video microwave STL.
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Julie M. Adkins and Robert D. Sorkin: "Effect of Channel Separation on Earphone-
Presented Tones, Noise, and Stereophonic Material," J. Audio Engineering Society,
vol. 33 pp. 234-239, 1985.
Subjects listened to 500-Hz tones, broadband noise, and stereophonic program ma-
terial through earphones and adjusted the channel separation, via a manual control,
until the degradation of the spatial effect became detectable. Mean channel separa-
tions ranged from 10 to 15.9 dB for the musical selections employed and from 13.7
to 16.8 dB for the noise and tonal stimuli. The results are discussed in terms of exist-
ing data on detectable stereo separation and on the discrimination of interaural
time differences. [Abstract ©Audio Engineering Society, Inc.]
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