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 4 of 8
5. Connecting Test CRU
The purpose of this test is to enable the RX sensitivity at the CT to be set to -98dBm
to within 1dB. This section provides details of the test set-up for the setting of the RX
gain control.
a) Set up the test equipment in preparation to connect to the shelf.
b) If using a voice test CRU then programme the CRU as follows with the same
programming information as that for the CRU at the ST associated with the
modem under test. If using a Data CRU program the CRU using STMON then go
to step 5(c).
• Remove the cover from the PSU
• Connect an MF or LD type telephone to the NTU
• To program the ST, depress the reset switch, (Type2 SW4 Type 4 SW2), in the
PSU for approximately 3 seconds. LED D8 will begin flashing to indicate the
CRU initialising and self test sequence. After approximately 10 sec, the CRU
initialising and self test sequence will be complete and the LED will be
extinguished. LED D9 will still be illuminated.
• Depress the Programming switch (Type2 SW3 Type 4 SW1). Lift the
telephone handset Off-Hook and wait for the 3 sec continuous “programming
start” tone of 1400 Hz, to be heard in the handset receiver.
• Enter the respective ST programming code on the telephone keypad, within 40
seconds of depressing the install switch. Should an incorrect programming
code be entered, an “incorrect code” tone shall be heard in the handset receiver,
which consists of 1400 Hz pulses for less than 1 sec on, and less than 1 sec off,
for a duration of 5 sec.
• Ensure that at the end of the programming sequence, the “code accepted” tone
is heard in the handset receiver, which consists of 1400 Hz pulses for 1 sec on;
1 sec off, for a duration of 5 sec. Replace the telephone handset.
• Depress the reset switch, (Type2 SW4 Type 4 SW2); The CRU will reset and
re-boot itself in accordance with the programming code entered.
c) Switch rack off by placing both breakers in the off position.
d) Disconnect terminations on DIP/LNA1 and TX filter.
e) Connect the cables and accessories to the CT rack for Modem Shelf setting up and
functionality testing as detailed in Figure 37. Set the 0-11dB variable attenuator to
a nominal 7dB (the insertion loss of the test circuit should be 109dB between point
a and b in Figure 37. In practice the setting of the attenuator will be a few dBs less
than the 7dB to account for the actual cable, connector and splitter loss. Due to the
microwave frequencies involved the commissioning items need to be calibrated for
the channel frequencies to be used.
Note: If the TX Filter is not fitted terminate the port of Splitter A as shown in Figure
37
f) Switch the power back on at the breakers.