Digital Repeater Line
DSP85 Series
WESTELL.COM
© 2016 Westell Technologies
14 June 2016 Doc. No. 960-1666-MNL rJ
1.877.844.4274
Page 49 of 77
Appendix A
Attenuation and Dynamic Range Guidelines
A.1
Donor Port
If a repeater is installed in an area with very strong wanted and/or unwanted signals, ensure that the overall signal
levels are optimized to be within the best operating range of the repeater. Avoid de-sensing of a nearby base station
site. You can accomplish these goals by properly attenuating the antenna port(s) in the path of the donor antenna(s).
Imagine that the particular repeater deployment is electrically moved farther from the base station using attenuators
that are equivalent to increasing the path loss from the donor antenna to the base station.
The following outcomes may result from the use of attenuators on the donor port(s) of the repeater:
Uplink output power, as reported by the unit, is reduced by the value of the attenuation, protecting nearby
base stations.
Downlink signal-to-noise ratio is high at the point of the attenuator, resulting in slight but negligible
reduction in downlink performance.
Other performance is essentially unchanged.
A.2
Server Port
Server port attenuation may also be necessary, particularly where a powered DAS is present. The selection guidelines
below apply to both server and donor ports. Use a signal generator to measure uplink signal strength properly.
If a signal generator is unavailable, place a test call while under the server antenna with the least path loss to the
repeater. This method should provide reasonable data.
The following potential outcomes result from the use of attenuators on the server port(s) of the repeater:
downlink output power, as reported by the unit, is reduced by the value of the attenuation.
Uplink incoming power from the DAS is reduced, along with potentially strong and/or harmful out-of-band
signals (including noise) that are generated by the DAS.
Choose accurate attenuator values to ensure that the maximum total power (higher of composite or in-band input)
applied to the donor and server port(s) does not exceed -25 dBm.
