User Manual
BRTS33 – Signal Booster
2.3 RF Configuration
The signal booster needs to be configured for the specific environment that it is installed in. The
uplink and downlink chain in the signal booster is configured individual with regards to gain of
the signal, muting of uplink signal and adaptive gain. Each of the parameters are handled below.
2.3.1 Uplink/Downlink gain setting
The uplink and downlink chains can be configured individually with what gain to apply to the
signals received. The gain can be adjusted between 40-70dB in 1dB steps. The maximum gain
that can be applied to the configuration is determined by the isolation between the donor side
and the mobile side. With a spectrum analyzer and signal source determine the isolation
between the two antenna sides on the operating frequency. The maximum gain is then
calculated with the below formula
Ma ≤IsolationdB +15dB
The gain applied to the uplink/downlink chain shall be less than
2.3.2 Adaptive Gain
The device is capable of automatically setting its gain appropriately to achieve a desired
downlink forward power level.
When adaptive gain is enabled, the gain and ALC level parameters are managed automatically
by the device and can no longer be set by the user. The user can influence the adaptive gain
operation by setting the Adaptive Gain Target Level. This parameter can also be changed after
adaptive gain is enabled. Since when adaptive gain is activated, the device automatically
manages gain values to prevent overdrive, overdrive protection cannot be active at the same
time as adaptive gain.
After enabling adaptive gain, the device will change uplink and downlink gain values
symmetrically to achieve the target downlink forward power.
The adaptive gain function has two modes of operation: fast mode and slow mode.
Fast mode is started in the following cases:
•After power up if the initial value of the adaptive gain function is "ON".
•After the user has switched on the function.
•The adaptive gain target level is changed.
•Uplink muting ceases to be active.
When fast mode is started, both uplink and downlink gain are set to the same value, and the
ALC levels are set to the factory default values. During fast mode operation the repeater
continuously monitors if there is overdrive or not. The monitoring is performed by checking the
overdrive level of the uplink and downlink modules every second. If the overdrive level is lower
than the allowed maximum value (3 dB for the BRTS33), that is, there is no significant overdrive,
the gain of the repeater is increased by 1 dB in both the uplink the downlink modules until the
downlink forward power reaches the current adaptive gain target level. If after any increase in
gain, the device detects an overdrive condition, the gain is decreased. This increase/decrease of
the gain is performed by modifying the attenuator value that is shown in the control software.
