COBHAM MBF-40 Americas, Руководство пользователя

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MBF-40 SMR900 PS REPEATER
PRODUCT DESCRIPTION AND USER’S MANUAL
Cobham Wireless – Coverage Date: 31-May-18 www.cobham.com/wireless
Doc. No. 00141UM Rev. 1.0 Page | VII
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 = ~ 12 dB
Assuming 10 service antennas: antenna splitter losses = 11 dB
Based on equation (2) Input antenna noise (to the antenna) = -42.8-12 -11=-65.8 dBm ERP
The in-band input noise to the antenna should be -42.8 -12-11= -65.8dbm ERP
Example: Out of band noise
Signal booster connected to 10 service antennas with a 100 m long ½ inch cable.
Losses of such a cable with the connectors = ~ 12 dB
Assuming 10 service antennas: antenna splitter losses = 11 dB
Based on equation (2) Input antenna noise (to the antenna) = -43.8 -12 -11= -66.8 dBm ERP
The out of-band input noise to the antenna should be -43.8 -12-11= -66.8 dbm ERP
NOTE: In this example there is a need to add an external band pass filter to attenuate the out of band noise by a further
3.2dB 1MHz away from the band edge. If fewer antennas are deployed then additional filtering will 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.