A2537-002/01 February 2020 6-13 SEMCO Proprietary Information
B. Sweep Range - This Auto Sweep Range feature automatically calculates and sets an optimum value
in kHz that provides for a demodulator acquisition time that applies to most data rates and demod
formats.
A narrow sweep range provides for faster demodulator acquisition and is normally used for higher
data rates. A wider sweep range is able to acquire lower data rates but requires a longer acquisition
time to acquire and lock on to the signal.
C. Sweep Rate (Hz/S) - This Auto Sweep Rate feature automatically calculates and sets an optimum
value in Hz/S that provides for a signal acquisition time that applies to most data rates and demod
formats. The sweep rate of the acquisition sweep range in Hz/second affects signal acquisition time.
A faster sweep rate results in a faster acquisition time. However, the sweep rate also has to be set
at a speed that guarantees reliable signal acquisition without “false lock”.
D. Mod Index – This Auto Mod Index feature applies to the Trellis FM demodulation mode. This feature
compensates for error in the initial transmitter deviation setting or change in transmitter deviation
during a mission. The display indicates the current average deviation. This feature is able to
compensate for a +/- 20% error in the transmitter deviation setting. Auto Mod Index settings are
described in paragraph 6.8.5.
E. IF FIR Filter Bandwidth – This Auto setting calculates the precise IF FIR filter value at the input to
the demodulator based on the data rate and demodulation format selected by the user. Disabling the
Auto IF FIR Filter setting provides the user with 15 IF FIR filter value selections based on the data
rate and demodulation format. This IF FIR Filter Bandwidth menu is updated with the appropriate
FIR filter values each time a different data rate and/or demodulator format is selected. Auto IF FIR
Filter Bandwidth settings are described in Section 4, paragraphs 4.3.2 and 4.3.4.
6.7.1 Auto Loop Bandwidths, Sweep Range and Sweep Rate Settings
Figure 6-21 shows how to enable the AUTO Sweep Range, Bandwidth and Sweep Rate using the Front
Panel LCDs and Keypad.
For both AUTO Bit Sync and Carrier Loop Bandwidths, the operator pushes the DEMOD button, uses
the UP (2) and DOWN (8) arrows to scroll to AUTO LOOP BW. in blue, and then pushes ENTER or
SELECT (5) to highlight the AUTO LOOP BW selection window in bright magenta. The operator then
uses the UP (2) and DOWN (8) arrows to select ON and pushes ENTER or SELECT (5.
Using the horizontal LEFT (4) and RIGHT (6) arrows, the operator can select <Ch2> and push ENTER or
SELECT (5) to highlight the AUTO LOOP BW selection window in bright magenta. The operator then
uses the UP (2) and DOWN (8) arrows to select ON and pushes ENTER or SELECT (5). The operator
repeats these steps for <Comb>.
For AUTO Sweep Range, the operator pushes the DEMOD button, uses the UP (2) and DOWN (8) arrows
to scroll to AUTO SWEEP RANGE in blue, and then pushes ENTER or SELECT (5) to highlight the AUTO
SWEEP RANGE selection window in bright magenta. The operator then uses the UP (2) and DOWN (8)
arrows to select ON and pushes ENTER or SELECT (5.
Using the horizontal LEFT (4) and RIGHT (6) arrows, the operator can select <Ch2> and push ENTER or
SELECT (5) to highlight the AUTO SWEEP RANGE selection window in bright magenta. The operator
then uses the UP (2) and DOWN (8) arrows to select ON and pushes ENTER or SELECT (5). The operator
repeats these steps for <Comb>.
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