Delay Difference Between Hd And Fm Outputs - Orban OPTIMOD-FM 8500S Operating Manual

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OPERATION

Delay Difference between HD and FM Outputs

If the HD output is driving a channel without pre-emphasis but using a lossy codec,
you may want to allow headroom to compensate for data reduction-induced peak
overshoots at the receiver, which might otherwise cause clipping. In our experience,
2 dB is typically adequate.
In order to make the receiver analog/digital crossfade free from comb filtering, the
time delays in the HD Radio's FM and HD channels must have a fixed and predictable
offset, correctly implementing the HD Radio receiver's "time diversity" processing. If
the 8500S's built-in diversity delay is defeated, the 8500S's HD output's delay is auto-
matically adjusted so that it always exactly 10.500ms longer than the FM output's
delay, regardless of the FM output's delay (which can vary depending on processing
settings). Therefore, the HD Radio exciter should be preset to compensate for this
10.5 ms offset between the FM output and HD output. Once you have done this, the
time diversity delay will always be correct even if you choose a 8500S preset that in-
vokes a different processing structure.
You can apply the 8500S's built-in diversity delay independently to any output emit-
ting the FM-processed signal. This eliminates the need to use the delay in the iBiq-
uity exciter, which allows you to apply the 8500S's composite output directly to the
transmitter's analog composite input. In turn, this allows you to use the 8500S's com-
posite limiter, increasing the loudness of the analog channel. When the diversity de-
lay is active, the 8500S always maintains precisely the same delay offset between the
analog and digital channels regardless of the preset in use.
Section Label
Input/Output:Output1
Input/Output:Output2
Input/Output:
AES Output 1 and
AES Output 2
Input/Output:
HD Digital Radio
BS.1770
Safety Limiter
Control Name
Phone Src
Out Source (analog L/R)
Out Source (AES 1)
Out Source (AES 2)
Out Level
Samp Rate
HD Bandwidth
Word Leng
Dither
Sync
Format
Out Level
Meter Select
HD HF Shelf EQ
Stereo/ Mono
Diversity Delay Trim
(HD) Polarity
BS.1770 Loudness Control
Threshold
BS.1770 Safety Limiter
Table 3-11: HD I/O Setup Controls
ORBAN MODEL 8500S
Values
HD / Monitor / FM
HD / Monitor / FM / FM+Delay
HD / Monitor / FM / FM+Delay
HD / Monitor / FM / FM+Delay
0... –20 dBFS; 0.1 dB steps
32, 44.1, 48, 88.2, 96 kHz
15, 16, 17, 18, 19, 20 kHz
14 / 16 / 18 / 20 / 24 bits
In / Out
Internal / Sync In
AES3 / SPDIF
0... –20 dBFS; 0.1 dB steps
FMOutLevel / HD GR
Pre / Post
Stereo / MonoL / MonoR / MonoSum
0.265 to 16.384 seconds
Positive / Negative
–31 to –11 LKFS/LUFS
On / Off