Motorola Solutions Inc. 89FC4825 Manuale Utente

 
Functional Description / Operation of Modules (Draft) 
 

for metering purposes so that SW can monitor the PA/BR output power.  Also, this voltage is provided to the power 

control circuitry within the PA to serve as the feedback signal in the power control loop for setting output power.  

The forward power meter along with the reverse power meter is used by SW to measure the VSWR presented to 
the PA output and to determine when an alarm condition is present. 

The SW requested power level may include one or more SW controlled adjustments based on various alarm 

conditions, if present, generated from monitored PA metering signals which are fed back to the SCM via an ADC 

converter.  Using the ADC metering circuitry, SW monitors the PA for alarm conditions, such as high reflected 

power/VSWR or high/low supply voltage, and takes action to reduce output power or dekey the station accordingly 
in order to protect the HW from damage or improper operation. 

Temperature monitoring circuitry is also contained within the PA.  When the temperature reaches a certain 

threshold, the PA fan turns on to reduce the operating temperature of the PA.  If the temperature continues to rise 

and reaches another predefined threshold, the BR output power may also be reduced in order to protect the HW 

from thermal failure.  Both the fan control and the power control manipulation for thermal protection is fully HW 
controlled, and requires no SW interaction.