Belar FMHD-1, Руководство оператора

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FMHD-1 Operator’s Manual
BELAR ELECTRONICS LABORATORY, INC. Page 13
parameter must be highlighted in green to be changed. So, rotate the encoder knob to place the cursor at
the parameter to be adjusted. Depress the knob momentarily to highlight the parameter green. Then, rotate
the knob until the desired value or condition is obtained. A second pressing of the knob returns the
indicated value to a yellow color, locking the adjustment. The cursor re-appears, and the encoder knob
can now be used to navigate within the blue popup pane to make other adjustments.
(In some cases, it is the cursor position which indicates the desired state. In the Program Selection Screen
for example, once the cursor is set at the correct position, another momentary pressing of the encoder
highlights the desired selection in green. Rotation of the encoder returns the cursor to the selection
category, where another momentary pressing of the encoder returns the parameter indicator to yellow and
restores navigational capabilities within the screen.)
4.2.6 Exiting a Popup Menu
A popup menu may be exited anytime by depressing and holding the encoder until the menu disappears .
Another, but more involved way to exit a popup menu is to simply reverse the procedure used to make a
selection in a Popup Menu. To exit a popup pane, if necessary, first remove any green parameter
highlighting by momentarily depressing the encoder knob. Then, move the yellow cursor to the X exit
symbol in the upper-right corner of the pane by rotating the encoder knob. With the “X” marked by the
cursor, momentarily depressing the encoder knob returns the user to the top-level screen.
4.3 FMHD-1 Modulation/Program-Level Readings (screen label change)
Due to the unique nature of the hybrid IBOC FM HD™ transmission system, the Belar FMHD-1 presents
two types of modulation indications. The analog FM channel for the hybrid system is monitored for peak
frequency deviation of the analog FM carrier, with 75.0 kHz peak deviation representing 100%
modulation—the FCC limit. This analog modulation indication is displayed in the “
Total
” bargraph on
the “Analog FM Stereo Screen”. Modulation indications for the IBOC digital channels are more correctly
referred to as
program levels . All levels in the digital channels are limited to an absolute maximum level,
referred to as full-scale . Because of the large amount of headroom normally maintained in digital audio
systems, the hybrid IBOC system introduces scale factors into the metering of the analog and digital
program channels. These factors allow the level indications to occupy a larger portion of the display
range for ease in reading. The scaled analog and digital program levels are presented in the Audio
Bargraphs Screen, along with the Scale Factor in force for the display. The default scale factors are
–6.0dBFS, or six decibels below full-scale, for the digital program audio and –10.0dBFS for the analog
program audio. The analog audio program level is metered after de-emphasis. The digital audio is
metered as heard.
The processing and indication of the analog and digital readings—whether for modulation levels or for
program levels—is handled in the same manner in the
FMHD-1 . Modulation data is collected over time-
windows set by the user. Peak indications are the highest modulation (or program level) of either polarity
occurring during a given window. The metering response is essentially instantaneous. In the
FMHD-1 ,
Average indications are computed from all of the peak readings taken during the most recent time
window. The Minimum indication is the lowest of the peak readings occurring during that same time
window.
The metering
Time Mode
s are “
Past
” time and “
Real
” time. The durations of the “
Past
” time
window or “
Real
” time peak-hold may be set to
0.25, 0.5, 1.0, 1.5, 2.0, 2.5, 3.0,