GE MDS Mercury 900, Справочное руководство

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05-4446A01, Rev. E Mercury Reference Manual 71
transmits while another is receiving, which prevents AP-to-AP
interference. Changing this parameter requires a radio reboot.
[
Free Run, GPS Required; Free Run ] Note: Do not use the Prefer GPS
setting.
• Channel Selection (AP only)—Opens a submenu where you can
specify channel usage.
• External GPS PPS Signal —Indicates whether or not an external
Pulse Per Second (PPS) signal is available. The setting may be
changed by pressing the spacebar after selection of the menu
item. This allows the radio to use the proper timing scheme
when frequency hopping.
• Advanced Control (Remote only)—Brings up a submenu (see
Figure 3-39 ) where additional communication parameters may
be set.
• Hardware Filter (900 MHz only)—This field provides a read-only
indication of the maximum bandwidth of the radio. [ 1.75 MHz or
3.5 MHz ]
Hand-Off Mode
Parameters
In a mobile or portable application, a Remote radio can move and asso-
ciate with different APs depending on its location. The process by which
the Remote ends the connection with one AP and begins a connection
with another AP is called “hand-off.”
Table 3-2 lists the hand-off
parameters for Remote transceivers and explains how they operate
under different signal conditions.
Table 3-2. Remote Hand-Off Parameters
Strict
Distance
Strict
Connection
Strict
Signal
Signal and
Distance
Signal, Dis-
tance, and
Bearing
Description The Remote
always chooses
the closest AP
regardless of
connection
status, RSSI,
etc.
The Remote will
only choose a
new AP when
the modem link
is lost. The Remote
chooses a new
AP when the
modem link is
lost or when the
RSSI or SNR
falls below the
threshold. The
Remote then
chooses the
closest AP. Operates the
same way as the
Strict SIgnal
method except
that the current
AP is abandoned
only if the next
AP is within the
distance
threshold. Operates the
same way as the
Signal and
Distance method
except that the
current AP is
abandoned only
if the bearing is
away from the
current AP.
AP(s) Used
(see note be-
low Table 3-2 )
Only closest AP.
Closest 3 APs. Closest 3 APs. Closest 3 APs;
AP must be
within Distance
Threshold. Closest 3 APs;
AP must be
within Distance
Threshold.
Max. Scanning
Seconds
N/A Applicable Applicable Applicable Applicable