User guide

Offset Method
An alternative to the termination method is to measure the return loss of a 20 dB offset.
This is similar to measuring an antenna that has been specified to have a 20 dB return loss
across the frequency of operation. A 20 dB offset provides a 20 dB return loss across a very
wide frequency range. Measuring the return loss with the 20 dB offset will provide a rela-
tively flat response across the operating frequency range of the Site Master.
Step 1. Set the frequency according to the device under test (cellular, PCS, GSM).
Step 2.
Press the MODE key and select
Freq-Return Loss mode.
Step 3. Connect the InstaCal module to the Site Master RF Out port and calibrate the
Site Master using the InstaCal module (page 3-6).
Step 4. Remove the InstaCal module from the RF Out port and connect the 20 dB Off-
set to the RF Out port.
Step 5. Measure the return loss of the 20 dB Offset. The level should be 20 dB, ±2dB
across the calibrated frequency range.
Step 6.
Press the MARKER key and set the M1 marker to
Marker To Peak. The M1
value should be approximately 20 dB return loss.
Step 7.
Press SAVE DISPLAY (page 3-10) name the trace, and press ENTER.
InstaCal Module Calibration Procedures
NOTE: The InstaCal module is not a discrete calibration component and it can
not be used at the top of the tower to perform line sweep measurements.
Check that the
CAL Off message is displayed in the upper left corner of the status window.
This indicates that the Site Master has not been calibrated. The following procedures detail
how to perform a calibration using the InstaCal module.
3-6
Chapter 3 Getting Started
InstaCal
Model I CN50
10 M
H
z-4.0G
H
z
Insta
C
al
MODULE
HOLD
RUN
START
CAL
AUTO
SCALE
SAVE
SETUP
RECALL
SETUP
LIMIT
MARKER
SAVE
DISPLAY
RECALL
DISPLAY
PRINT
MODE FREQ/DIST
AMPLITUDE
MEAS/DISP
SYS
ENTER
CLEAR
ESCAPE
ON
OFF
/
1
2
4
5
6
7
8
9
0
3
+
-
.
S332D
Figure 3-3. InstaCal Module Calibration