Options – Comtech EF Data MIDAS Version 4.X Basic Configuration User Manual
Page 66
MIDAS 4.2 Basic Configuration, Rev. 1
2–32
Setup and Operation
A
A
c
c
q
q
u
u
i
i
s
s
i
i
t
t
i
i
o
o
n
n
R
R
a
a
n
n
g
g
e
e
The Acquisition Range is a value (in kilohertz) that is used to provide
additional guard band for the bursting Inbound Control Channel. This value is
used to complement the operation of Automatic Frequency Control (AFC), and
allows nodes a wider sweep range when performing transmit acquisition by the
nodes in systems where satellite frequency translation error may exceed the
limited demodulator sweep range of the SNM-1001 Control Channel modem.
This value is stored in the database and used by the bandwidth manager task to
assign frequencies for traffic channels, with respect to the additional guard
band. This value is also sent to the nodes when they are commanded to become
“enabled”, where it is stored and then used by the Node Control modem to
limit the transmit sweep range when performing transmit acquisition. This
allows the node to have a controlled sweep range to compensate for excessive
frequency offsets in the network, while preventing interference with adjacent
carriers.
Options
S
S
t
t
a
a
t
t
u
u
s
s
P
P
o
o
l
l
l
l
I
I
n
n
t
t
e
e
r
r
v
v
a
a
l
l
This is a timing parameter (in seconds) that is used to detect if the node is
“alive”, or functioning properly. Status polls apply only to enabled, active
nodes. Every poll interval, the controller server will send a keep alive poll to
the node. If the node responds, then the node is “alive”. If there is no response
from the node after three consecutive polls, the node is marked inactive by the
controller server.
E
E
n
n
a
a
b
b
l
l
e
e
U
U
p
p
l
l
i
i
n
n
k
k
P
P
o
o
w
w
e
e
r
r
C
C
o
o
n
n
t
t
r
r
o
o
l
l
This checkbox allows the operator to enable/disable the Uplink Power Control
option.
Uplink Power Control (UPC), a standard feature of the MIDAS system, is the
method used to establish a network-wide reference for power. Specifically,
UPC is used to ensure that the Outbound Control Channel carrier is
downlinked from the satellite at a constant power level. This reference allows
each of the nodes in the network to determine and report (via regular polling
from the controller server) if, and to what degree, downlink degradation of a
node (and its associated traffic channels) may be occurring due to fade,
whether from rain or other non-atmospheric conditions.
The SNM-1002 LinkSync
modem is used to constantly measure the
reference (Outbound Control Channel) carrier. The controller server compares
the measured E
b
/N
o
with a “Reference E
b
/N
o
” stored in the database, and
adjusts the Outbound Control Channel modem’s (SNM-1001) transmit power
level from the default power level, compensating for any uplink degradation,
thereby maintaining a constant transmit power level (downlink) at the satellite.