Cobham Wireless
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BSF0060 User Handbook
www.cobham.com/wireless
Document number: BSF0060HBK
Issue number: 5
Date: 14/05/2018
Page 9 of 43
Example: In band Noise
Signal booster connected to 10 service antennas with a 100m long ½ inch cable.
Losses of such a cable with the connectors = ~ 12dB
Assuming 10 service antennas: antenna splitter losses = 11 dB
Based on equation (2) Input antenna noise (to the antenna) = -46-12 -11=-69 dBm ERP
The in-band input noise to the antenna should be -46 -12-11= -69dbm ERP
Example: Out of band noise
Signal booster connected to 10 service antennas with a 100m long ½ inch cable.
Losses of such a cable with the connectors = ~ 12dB
Assuming 10 service antennas: antenna splitter losses = 11 dB
Based on equation (2) Input antenna noise (to the antenna) = -66 -12 -11=-89dBm ERP
The Out of-band input noise to the antenna should be -66 -12-11= -89dbm ERP
NOTE: In this example there is no need to add an external band pass filter to attenuate the out of
band noise. If fewer antennas are deployed then additional filtering may be required
Conclusion:
Good engineering practice requires that in general when the out of band noise measured at the
service antenna input is more than -70 dBm per 10 kHz measurement bandwidth, an external band
pass filter should be added to attenuate the out of band noise level.
All Cobham Wireless repeaters include high selectivity duplexers and filters to attenuate the out of
band noise. Should additional filtering be required, we have a comprehensive range of interference
filters which can be supplied upon request.
