Comba Telecom Ltd. RX4122-B Manual De Usuario
INSTALLATION GUIDE FOR RX-4122
ENU STATUS : 1-0-1
Copyright - refer to title page
Page 50
The in-band input noise to the antenna should be
– 51 – 12 – 0 – 11= -63dBm ERP
For example: Out of band noise
RX-4122 PS BDA 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
Out of band rejection of filters: more than 45dBc
Based on equation (3) Input antenna noise (to the antenna) =
RX-4122 PS BDA 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
Out of band rejection of filters: more than 45dBc
Based on equation (3) Input antenna noise (to the antenna) =
– 31 –12 – 45 – 11= – 99dBm ERP
The Out of-band input noise to the antenna should be
– 31 –12 – 45 – 11= – 99dBm ERP
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 Comba BDAs include high selectivity duplexers and filters to attenuate the out of band noise.
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 Comba BDAs include high selectivity duplexers and filters to attenuate the out of band noise.
Compliance with FCC Part 90.219 (d)(6)(i)
The deployment rules require that the ERP of intermodulation products should in general not exceed -30dbm.
This is not a formidable task since in the vast majority of the passive DAS installations; the signal loss in the
DAS due to splitting to multiple antenna and cable losses is significant.
As well as the above RX-4122 PS BDA is more likely to be used in a multicarrier environment (more than 2
carriers), which in turn will reduce the intermodulation products produced by the device.
The following statement is already in the user manual to highlight the requirement to the installer for the
instances where the above does not reduce the ERP of the intermodulation products to -30dBm.
‘The installation procedure must result in RX-4122 PS BDA complying with FCC requirements 90.219(d). In
order to meet FCC requirements 90.219(d), it may be necessary for the installer to reduce the UL and/or DL
output power for certain installations.’
The deployment rules require that the ERP of intermodulation products should in general not exceed -30dbm.
This is not a formidable task since in the vast majority of the passive DAS installations; the signal loss in the
DAS due to splitting to multiple antenna and cable losses is significant.
As well as the above RX-4122 PS BDA is more likely to be used in a multicarrier environment (more than 2
carriers), which in turn will reduce the intermodulation products produced by the device.
The following statement is already in the user manual to highlight the requirement to the installer for the
instances where the above does not reduce the ERP of the intermodulation products to -30dBm.
‘The installation procedure must result in RX-4122 PS BDA complying with FCC requirements 90.219(d). In
order to meet FCC requirements 90.219(d), it may be necessary for the installer to reduce the UL and/or DL
output power for certain installations.’