7;5;6\VWHPV,QF
Manual 7-9547-1 12/09/14 Page 14
rarily interconnected then power is applied to the
system by plugging the control unit’s AC cord into a
suitable AC outlet or by connecting the DC power
cable to a suitable -48 VDC supply. The following
start-up sequence occurs.
1) At turn-on, the three front panel status LED’s
will all flash then dim. This will last for a few sec-
onds while the systems micro-controllers boot-
up.
2) During the next few seconds the base control
unit will establish communications with the
tower box. The display panel will present the
message “Connecting to Tower Controller”.
3) After the power-up sequencing is complete the
screen should show the default display. See
below. The status LED for each active amplifier
will glow a steady green and the status LED for
the inactive (stand-by) LNA will be dark.
The tower top amplifier system is software directed
so control of the system is accomplished via user
interface with the front panel using the display
screen and the four menu selection buttons. A flow
chart showing all of the possible user menu selec-
tions is shown in
Figure 7.
Bench Testing
The purpose of the bench test is to verify that all of
the system components are working correctly and
to measure the systems sensitivity before climbing
the tower to mount the tower top box. One station
receiver is selected and the test is performed at
this frequency. Short temporary cables are used to
interconnect all components. A SINAD meter (or a
bit error rate meter if required) is used for the test
along with a signal generator.
1) The stand-alone receiver sensitivity is mea-
sured and recorded first.
2) To interconnect the equipment connect a cable
between the main port on the tower box and the
main port on the base unit. Also connect a
cable from test port connector to the test port
connector
. Figure 8
shows all of the equipment
interconnections for bench testing. Inject the
test signal into the tower box antenna port. Be
sure that the signal generator is setup for a 3
KHz deviation with a 1000 Hz tone (analog) or
proper pattern for BER testing. Connect the
SINAD/Bit Error Rate meter to a receiver and
connect the receiver to one of the RF output
ports on the back of the base unit.
3) Measure and record the systems bench test
static sensitivity. The sensitivity value will vary
depending on the amount of internal program-
mable attenuation selected via software inter-
face. The bench test measurement should be
taken with the default attenuation values. As
shipped from the factory the default TTA NET
Gain attenuation for the system is 6.0 dB and
the default Distribution attenuation is 4.0 dB.
4) Select the other tower top amplifier and check
that the bench test static sensitivity value
remains nearly the same. This will insure that
both amplifiers in the tower top box are function-
ing properly. To select an alternate tower-top
amplifier press the associated amplifier select
button on the front panel, the status LED will
begin to flash, then press the ENTER button to
finalize the selection.
AMPLIFIER BYPASS
The system is designed with a bypass function
which allows the antenna to be connected directly
to the test port. In this mode of operation the front
panel test port is electronically re-routed to the
main transmission line and the amplifier circuit in
the TTA is bypassed. This will allow for sweeping
the antenna from the front panel test port. As part
of bench testing the system this function needs to
be tested. To temporarily interconnect the equip-
ment connect a cable between the main port on the
tower box and the main port on the base unit. Also
connect a cable from test port connector to the test
port connector
.
Using the front panel display inter-
face place the unit in the bypass mode. When the
system enters the bypass mode there should be an
RF signal path between the front panel test port on
the base unit and the antenna port on the tower top
box. Note that after 1 minute of being in the bypass
Display Panel default display
