Tait TB8100 Installation And Operation Manual

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Contents

Tait TB8100 Installation And Operation Manual Manual pdf 42 page image

42 Functional Description TB8100 Installation and Operation Manual© Tait Electronics Limited June 2005base station operation, but is also used for single base station operationbecause it provides the I 2 C current source normally provided by the PMU.Note The dual base station subrack interconnect board has a set ofswitches which must be set according to the type of base stationsystem in the subrack. Refer to “Replacing the Subrack Intercon-nect Board” on page 98 for details of the switch settings.Power Saving operation in a 12V PA base station requires an externalconnection between the reciter and 12V PA (refer to “12V PA PowerSaving Control Connection” on page 124). For details on Power Saving ina 12V PA base station, refer to “12V PA Operation” on page 60.Constraints The dual base station control panel imposes the same constraints on theoperation of a dual 12V PA BSS as those described in “Service Kit” onpage 40, except that those which refer to the PMU do not apply.In addition, because there is no PMU fitted, we recommend the followingService Kit settings for 12V PA base station operation: Disable the “No PMU detected” alarm on base stations 1 and 2.4.2 System Control BusThe system control bus, see Figure 4.4 on page 44, provides thecommunications link between the modules in the TB8100 BSS. It providesthe following physical paths: I2 C communications between modules RS-232 communications between the reciter and Service Kit andCalibration Kit software, via the control panel port fan power from the PA and PMU speaker and microphone signals to and from the control panel power connections for the control panel.The system control bus has been designed so that, if a major fault occurs onthe bus, the basic operation of the base station is unaffected, but somefeatures will not operate correctly. For example, if the PA is disconnectedfrom the bus: the ‘PA not detected’ alarm is generated in the reciter; however,transmission still takes place because the transmit RF and key signals aretransmitted from the reciter to the PA via the interconnecting coaxialcable the PA is unable to turn on its fan. Depending on the ambienttemperature at the site and the transmit duty cycle, this could allow thePA to heat up to the point where it reaches the upper temperaturethreshold. At this point it will begin power foldback, protecting theequipment from damage.