User's Manual

Transmit & Receive Antenna VSWR – continued
May 2000
G-5
SC 4812T CDMA BTS Optimization/ATP
Table G-2: VSWR Measurement Procedure – Advantest Test Set
Step ADVANTESTAction
3 Preform the following to instruct the calibrated test set to generate a CDMA RF carrier (RVL call)
with all zero longcode at the assigned RX frequency at –10 dBm:
 Push the ADVANCE Measurement key.
 Push the CDMA Sig CRT menu key.
 Push the FREQ Entry key:
– For 1900 MHz systems, set RF Gen Freq to center frequency of actual CDMA carrier between
1930–1990 MHz for TX and 1850–1910 MHz for RX.
– For 800 MHz systems, set RF Gen Freq to center frequency of actual CDMA carrier between
869–894 MHz for TX and 824–849 MHz for RX.
– For 1700 MHz systems, set RF Gen Freq to center frequency of actual CDMA carrier between
1840–1870 MHz for TX and 1750–1780 MHz for RX.
 Push the LEVEL Entry key; set to 0 dBm (by entering 0 and pushing the –dBm key).
 Verify that ON is active in the Output CRT menu key.
 Verify that OFF is active in the Mod CRT menu key.
 Push the CW Measurement key.
 Push the FREQ Entry key.
– Push the more 1/2 CRT menu key.
– Set Preselect CRT menu key to 3.0G.
 Push the Transient Measurement key.
– Push the Tx Power CRT menu key.
– Push the LEVEL entry key (set to 7 dBm by entering 7 and pushing the the dBm key).
– Set Avg Times CRT menu key to ON. Set to 20 (by entering 20 and pushing the Hz ENTER
key).
 Push the REPEAT Start key to take the measurement.
4 Record the Burst Power display on the communications analyzer and Note as P
S
for reference.
5 Install the antenna feedline to the output port of the directional coupler.
6
 Push the Auto Level Set CRT menu key.
 Push the REPEAT Start key to take the measurement.
7 Record the Burst Power on the communications analyzer and Note as P
A
level for reference.
Record the difference of the two readings in dBm.
8 Calculate the VSWR per the equation shown to the right.
Where:
R
L(
dB) = P
A
(dBm) – P
S
(dBm)
P
A = Power reflected from antenna
P
S = Power reflected from short
A calculated value of –13.98 dB equates to VSWR of better than 1.5:1.
VSWR 




1  10
RL
20
1 – 10
RL
20




. . . continued on next page
G