7;5;6\VWHPV,QF
Manual 7-9547-1 12/09/14 Page 27
If left unattended, after about 1 minute
the input of the active amplifier will
automatically switch back to the
antenna and on-air signals will again
pass through to the station receivers.
6) From the default display, use the ARROW but-
tons to scroll to the SENSITIVITY menu choice
then press the ENTER button.
7) Use the ARROW buttons to scroll over to the
STATIC W/LOAD menu choice and press the
ENTER button.
8) Use the ARROW buttons to dial in the static
sensitivity value (from the signal generator) and
press the ENTER button to save the information
into memory. By storing the sensitivity value at
the time of installation it can be compared with
future tests and used as an indication of system
degradation or failure. In general, the sensitivity
measured with the antenna will be less than
that measured with the load unless site noise is
at a minimum.
The sensitivity value measured in
step 5 is less (30 dB plus Test Line
loss) than the actual sensitivity
value.
Effective System Sensitivity
The Effective System Sensitivity is the sensitivity
as seen by the subscriber. This represents the talk-
in coverage component of the infrastructure. To
determine the Effective System Sensitivity the sig-
nal level into the first amplifier must be known. The
easiest way to achieve this is to inject a test signal
into the Test Port (located on the front panel of the
base unit) and measure the BER or SINAD of the
test receiver. The effective system sensitivity can
only be measured while the active tower-top LNA is
connected to the antenna. Once you have made
the measurement the actual effective system sen-
sitivity can be calculated.
Measuring Effective Sensitivity
(Antenna Connected)
The Effective system sensitivity should be taken
under normal conditions as well as with all trans-
mitters producing full power. All transmitters keyed
will show the worse case situation. To test the sys-
tems effective sensitivity through the test port with
the antenna connected to the amplifiers perform
the following steps;
1) The signal generator should be connected to
the front panel test port.
2) The test receiver and SINAD meter (or bit error
rate meter if appropriate) should be connected
to one of the RF outputs at the rear of the base
unit.
3) Under normal conditions the antenna is con-
nected to the amplifiers so no software interac-
tions are required. Be sure the signal generator
is setup for a 3 KHz deviation with a 1000 Hz
tone (analog) or proper pattern for BER testing.
4) Adjust the signal strength from the signal gener-
ator until the 12 dB SINAD or 5% BER point is
acquired. This determines the systems sensitiv-
ity in the presence of site noise. Record this
value in the base control unit’s memory for
future use.
5) From the default display, use the ARROW but-
tons to scroll to the SENSITIVITY menu choice
then press the ENTER button.
6) Use the ARROW buttons to scroll over to the
REFERENCE W/ANT menu choice and press
the ENTER button.
7) Use the ARROW buttons to dial in the effective
sensitivity value and press the ENTER button to
save the information into memory. By storing
the sensitivity value at the time of installation it
can be compared with future tests and used as
an indication of system degradation or failure.
The sensitivity value measured in
step 4 is less (30 dB plus the Test
Line loss) than the actual sensitiv-
ity value.
Degradation
The difference between the static sensitivity (load-
connected) and the effective sensitivity (antenna-
connected) is the system degradation which can
be caused by noise or interference (such as a user
on an active channel). At 800 MHz it is unusual to
have degradation greater than 2 dB (and even this
is rare). The degradation value should be recorded
NOTE
NOTE
NOTE
