Hemisphere GPS MBX-4, Руководство пользователя

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3: MBX-4 Configuration and Operation
Background Search - During the Background Search, the second
channel examines all frequencies at both the 100 and 200 bps MSK bit
rates to identify beacons possessing superior signal quality. If a DGPS
broadcast is identified that exhibits a 2 dB greater signal strength than
that of the primary station, the receiver will automatically switch to this
beacon. No loss of lock occurs on the primary station during the
background scan.
The MBX-4 stores the current primary beacon in memory so that it is
available upon subsequent power-up. You may force a new Global
Search at any time using the proprietary NMEA 0183 command defined
in Chapter 5.
Manual Mode
In Manual tune mode, you may select a specific frequency and bit rate
for the receiver to tune to, or simply specify the frequency, allowing the
MBX-4 to identify the correct MSK bit rate on its own. This mode of
operation is most useful when working in an area where you know the
frequency though not necessarily the MSK bit rate of the closest
beacon.
The MBX-4 also provides the capability to select a beacon by name
from the World Beacon Table stored within receiver memory. You can
update this table via the MBX-4 serial port, as detailed in Chapter 4.