— 9 —
This can be done whether or not the station is transmitting
an HD Radio digital signal. Any of the possible digital
channels may be selected,
HD1
through
HD8
.
The 632 does not automatically cross-fade or switch-over to
the FM program when an HD Radio transmission is absent.
NO HD1
(or whichever digital channel is selected) will show
on the display, and after a few seconds an
HD LOSS
alarm
will be triggered.
PLEASE KEEP IN MIND:
The HD Radio system employs
complex coding of the stereo audio program into a digital
data stream. This coding includes powerful error-correction
techniques to ensure solid reception under adverse condi-
tions. The HD Radio receiver must buffer a generous
amount of the data stream before the program can be
heard, so please be patient. It may take several seconds af-
ter tuning an HD Radio broadcast before you are able to
hear the audio.
If the station is indeed
broadcasting HD Radio
programming, the
DQ
(Digital Quality) bar-
graph will appear, along
with station call letters.
The series of bars to the right of
DQ
is an elementary indica-
tor of digital signal ‘robustness’ and is derived from a num-
ber of parameters. Generally it’s an all-or-nothing indica-
tion, and in any case a relative one.
When the receiver is tuned and set to the desired mode,
push the jog wheel so that neither
FREQ
nor
FM
nor
HD
is
blinking. Your setup will be transferred into non-volatile
memory and the jog wheel released to navigate to other
menus.
HD Radio Digital-Loss Alarm
If the 632 receiver has been manually set to the HD Radio
reception mode, but either the station is not transmitting a
digital signal or reception conditions prevent the receiver
from locking onto the digital broadcast, after a short delay
HD LOSS
will begin flashing on the front-panel LCD.
The rear-panel
D
terminal gives an NPN transistor satura-
tion to ground on a digital-signal-loss alarm. This may be
used to actuate a relay or light a remote LED.
— 10 —
Carrier Strength and Alarm
Turn the jog wheel to
Menu Screen 2. The up-
per bargraph gives a
representation of
RSSI:
,
which stands for Re-
ceived Signal Strength
Indication. This is a measurement of the relative strength
of the FM carrier and has no relevance to the dB scale beside
the LCD window, which is used only for audio level meas-
urement.
The lower LCD scale is labeled
ALRM:
and has a single tic
mark off to the right. Push the jog wheel and
ALRM:
will
begin to blink. Now turn the knob and note that the single
tic mark can be positioned anywhere beneath the
RSSI:
scale.
During normal receiver operation, anytime the
RSSI:
bargraph falls below the tic mark
LOW SIGNAL
will flash on
the LCD screen and a carrier-loss alarm will be sent to the
rear-panel connector. The rear-panel
C
terminal gives an
NPN transistor saturation to ground on an alarm, which may
be used to actuate a relay or light a remote LED indicator.
Set the carrier-loss trigger point about a quarter of the way
down from the top of the RSSI scale. This will allow for
normal signal fading over a typical receive path, but will
still alert the user to a valid carrier loss or transmitter pow-
er problem. When the point has been set, push the knob
again to fix the alarm point in memory and to release the
menu.
The Audio Loss Alarm
Navigate to Menu 3 and push the knob.
A-LOSS:
will begin
blinking. Turn the knob to dial-in the desired audio loss
alarm delay time. This is the time in seconds between the
onset of ‘dead air’ and an
AUDIO LOSS
alarm. The delay
may be set to
OFF
, which
deactivates the alarm, or
programmed in one-
second intervals up to
120sec
(2 minutes).
