User's Manual

78 UltraWAVE BTS Installation and Commissioning Guide, Release 6.5A
5-3 Antenna Cabling and Power Verification
5-3.1 Voltage Standing Wave Ratio (VSWR) Check
The VSWR check should be performed by the team responsible for the antenna installation. The
purpose of the check is to ensure the integrity of the antenna and the antenna connection by
determining whether the reflected power reading is higher than the recommended value. The reflected
power is defined as a ratio of the power output versus the reflected power return. This value is
determined by two key factors: the power output from the chassis and the loss due the length and type
of the cable.
The recommended test approach is to use an in-line, forward/reverse power meter (for example, the
NAS model by Rohde and Schwarz) installed between the chassis and the antenna cable. This approach
validates that the antenna and cable are good. It also verifies that the transmit power from the chassis is
within tolerance limits. The VSWR at the antenna port should be less than or equal to 1.5:1.
Listed below are threshold values assuming a VSWR of 1.5 at different levels of cable loss (due to length
or cable type). The estimated return loss should be greater than or equal to the values below.
5-3.2 Verifying BTS RF Performance without Racal
After performing the BTS commissioning as described in the previous section, use the following
procedure to check the performance of an on-line BTS without using a Racal test procedure.
Required Test Equipment
• GSM-compatible RF Power Meter
• 50 Ohm dummy load
• 100 W, 30 dBm attenuator
• Two mobile telephones
Required Network Configuration
To perform satisfactory RF performance tests, the BTS must be connected to an operational BSC/MSC
and OMC to enable call processing, as the SS7 must be enabled for the BTS to transmit. Make sure you
commission the BTS as described in the previous section before performing this procedure.
5-3.3 Verifying TRX Output Power
This test must be done to each TRX in the system. After completing the test for the first TRX, move on to
the next until you have tested each. Use the following procedure:
This procedure is NOT a substitute for the Racal tests. Please refer to the
interWAVE Radio Test Manual
to test the output power of the BTS.