Installation Manual Part 5

PRELIMINARY
D-8
BWX 8415 Basestation Installation and Commissioning Guide
OL-19519-01
Appendix D RF Center Frequency and Interference Analysis Guidelines
Spectrum Analyzer Settings
Resolution Bandwidth
The resolution bandwidth parameter for the Time Domain test acts similarly to the span function in the
Frequency Domain test. The bandwidth parameter opens up the receiver of the Spectrum Analyzer to
look at all signals across that bandwidth for the given sweep time. The smaller the bandwidth, the more
accurate the readings displayed.
This parameter also determines the frequencies that are to be tested for a given range. The BS uses a 5
MHz channel. If the Spectrum Analyzer can be programmed with a bandwidth of 5 MHz, then the center
frequency to be tested is every 5 MHz. Some analyzers are only able to be programmed to 1 MHz,
resulting in a center frequency test step of 1 MHz. This results in more frequencies to be tested, but a
more accurate indication of where the interference is located in the spectrum.
Frequency examples:
5 MHz Resolution Bandwidth 1 MHz Resolution Bandwidth
3.4025 GHz 3.4GHz
3.4075 GHz 3.401GHz
3.4125 GHz 3.402GHz
Sweep Time
The sweep time parameter is the amount of time that it takes the analyzer to scan the set bandwidth. One
transmit and receive frame on the Cisco system is 10 ms, so a sweep time of 40 ms shows 4 frames, and
400 ms shows 40 frames.
Figure D-7 Example of a Time Domain Test