— 15 —
“Full” modulation is de-
noted by the large block
opposite the
0dB
mark-
ing on the panel. The
meter resolves +1, +2
and +3dB above 0dB,
and from 0dB down it is calibrated in 0.5dB steps to –15dB,
and then in 1dB steps to –21dB.
For FM reception, the
0dB
panel marking represents ±75kHz
carrier deviation. A 400Hz monaural test tone would take
the meter to exactly
0dB
. Receiver de-emphasis must neces-
sarily be factored into the reading at higher frequencies,
and of course the 19kHz stereo pilot consumes the top 1dB
of stereo broadcast modulation. Aggressively-processed
program audio should consistently peak the bars to about
–1dB.
When HD Radio broadcasts are being received,
0dB
corre-
sponds to the iBiquity specification of –3dBFS for an abso-
lute limit of program peak excursions.
Headphone Volume
(HD Radio Menu Screen 8; FM Menu 9)
A front-panel
PHONES
jack offers a convenient monitoring
point for Receiver setup and casual listening. As a pair of
headphones is plugged into the front-panel jack, the LCD
screen automatically goes to this Menu Screen.
Headphone
Vol
will begin blinking and the panel knob may be adjusted
for a comfortable listening level.
The LCD shows an arbitrary numerical value and a bargraph
representation of the headphone volume. Once volume is
set, push the knob to save the setting to memory.
Line Output Levels
(HD Radio Menu Screen 9; FM Menu 10)
You may set analog and
digital audio levels leav-
ing the INOmini 639 on
this Menu Screen. The
numbers shown refer to
the peak levels of either
FM or HD Radio program signals at 100% modulation.
Push the knob and
ANA Out
will start to blink. Turn the
knob to set the levels of the balanced left and right analog
— 16 —
outputs to any value between –15dBu and +15dBu in 0.2dB
increments.
Push the knob again to set
DIG Out:
, the AES digital line
output level. Numbers reference ‘dBFS,’ or dB with refer-
ence to digital full-scale. The adjustment range is –30dBFS
to 0dBFS in 0.2dB increments.
PI / CL / Time
(FM Menu Screen 11)
PI:
is the station’s four-character, hexadecimal identifier,
the station’s “digital address.”
In North America the PI code is numerically derived from
station call letters. ‘Reverse-decoded’ call letters for the PI
code shown adhere to the RBDS standard and will display in
the
CL:
field.
In some instances, North American PI codes derived from
call letters will conflict with use of the RDS TMC (Traffic
Message Channel) function. In those cases stations may
adopt a ‘bogus’ PI code that will back-calculate to incorrect
call letters. If the incorrect call letters happen to be the
same as another station’s legitimate assignment, the two
stations must necessarily be in widely-separated coverage
areas to avoid RDS housekeeping conflicts.
Another RDS utility sets the listener’s radio clock to the cur-
rent local time. This is a double-edge sword, however, as a
change in time zones within the broadcaster’s primary cov-
erage area could cause trouble and alienate listeners. For
this and other reasons, many broadcasters feel a responsi-
bility
not
to implement this RDS timekeeping utility.
The lower line of FM Menu Screen 11 will scroll the RDS
Clock/Time field. This
will include the date, the
current time in 24-hour
notation, and the offset
from UTC (Universal Co-
ordinated Time).
