User Manual

AS4000 Release3 and Release 4 Central
Terminal Installation and Commissioning
DLP-016
605-0000-432
Issue 1.3a Date 18th October 1999
Page 3 of 8
POWER
METER
CT
15W
Termination
RF Power meter
connection when
measuring Modem
Shelves 1 & 2
TX Output Power
DIP/LNA1 TX Filter
15W
Termination
POWER
METER
CT
RF Power meter
connection when
measuring Modem
Shelves 3 & 4
TX Output Power
DIP/LNA1 TX Filter
Figure 40. Power Level measurement Test Set-up
d) Restore power to the rack.
e) The single user output power is 21dBm. The TX output power level is maintained by a
power control loop in the system. For the power loop to work the CT RF card needs to
generate greater than +21.75dBm, this condition can be achieved by using the Sitespan to
set two users in service without any STs in operation. This forces the two modems ( i.e.
one modem card) to stay in the high rate acquisition mode. Two users provide an output
of 24 ± 1.0dBm.
f) For the CT to reach its nominal output power from zero using the control loop would take
a considerable length of time. To bypass this process, the power control loop may be
overridden using the Sitespan to set the TX power the control voltage.
g) Using the Sitespan select the RF Card view from the Shelf view.
h) Set the transmitter volts to 2.2 volts by using the Up/Down button. Observe that the auto
levelling sets the Output power to 24 ± 1.0dBm.
i) Record results
j) Switch off rack. by placing both breakers in the off position.
k) Ensure that the power Output is at steady level before setting up the RX gain control.