User's Manual

Doc. No.
Rev.
Date
1.00
2011-12-08
Damm Cellular Systems A/S, Denmark
TETRAFLEX
®
V7.5 MANUAL - Antenna System for BS41x
TetraFlex® 7.5 Manual 4-8
Inter-modulation can be calculated with the formulas:
3
rd
: f = 2xf1 – f2
5
th
: f = 3xf1 – 2xf2
7
th
: f = 4xf1 – 3xf2
RX frequencies should never be selected to be on frequencies, where 3
rd
-order IM is present
for high-power Base Stations. However, 3
rd
order IM is only possible with special Base
Stations with a TX frequency separation larger than the guard-band between RX and TX
bands.
For high power Base Stations running with Duplex Filter, 5
th
order should always be avoided,
and 7
th
-order should preferably be avoided as well.
The BS41x is provided with an RSSI indication accurate down the RX noise floor. This can be
easily used to check for disturbance from the transmitters.
First, display the RSSI for all carriers with the OM command:
B/21/1
Note the actual RSSI and the try to key all the transmitters simultaneously with the command:
B/10+
Check the RSSI again. The difference in RSSI indicates directly the reduction in sensitivity
due to disturbance from the Transmitters.