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The factory-default cor-
rection rate may be reset
by the user. The
Sam-
ples/Second:
slider may
be set to any figure be-
tween 10sps and 1000
sps. If the Nielsen PPM is
not an issue, you can safely set this to 200sps. Either drag the
slider, or highlight the current number and enter your prefer-
ence.
Jump on Boot
The JUSTIN 808 has a feature that negates a long wait to
achieve error correction after an AC mains power interruption.
A switch marked
Jump on
boot
may be found under the
AES Audio Adjustments
sub-
menu. The factory default
for this switch is
On
. This
means that as soon as the
JUSTIN 808 acquires correla-
tion, it will correct the delay error and bring the analog FM and
digital HD1 programs into time alignment instantly. There real-
ly is no valid reason for turning this switch
Off
, unless the slow
alignment recovery following a power glitch is somehow con-
sidered a plus.
PROGRAM LEVEL CORRECTION
The JUSTIN 808 can automatically correct for up to ±6dB loud-
ness difference between the FM and HD1 programs, but only
when it is connected in-line with the processed AES digital au-
dio feeding HD1 programming into the exciter or exporter. It
would not be possible to control the level of the FM airchain
signal, as the FM audio processor would negate any level
change in the signal feeding it, and changing the level after FM
program processing would directly affect FM carrier deviation.
Measuring
Loudness
The JUSTIN 808 measures and responds to true-r.m.s. levels of
the off-air FM and HD1 broadcasts, and incorporates relevant
provisions of the recommended ITU BS.1770-3 loudness meas-
urement specification.
It is important to note, however, that many broadcasters em-
ploy separate, and often quite different, audio processing
methods for their FM and HD1 simulcasts. Thus the two pro-
grams can sound a bit different to a listener in an ideal listen-
ing environment. Nonetheless, maintaining a long-term loud-
ness match does help lessen the audibility of the inevitable
fades between reception modes, a necessary part the HD Radio
‘hybrid mode’ operation.
