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   Compute the temperature of a receiver. 
   t is the ambient temperature of the receiver and tE is the effective 
   input noise temperature.
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   Form:
   tR = TReceiver( tA, lFRX, tF, tERX )
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   ------
   Inputs
   ------
   tA            (1,1)  Antenna temperature
   lFRX          (1,1)  Feeder loss
   tF            (1,1)  Feeder temperature
   tERX          (1,1)  Receiver temperature
                        
   -------
   Outputs
   -------
   tR            (1,1)  Temperature at input
                        
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	References:	Maral, G. and M. Bousquet. (1998.) Satellite Communications
               Systems. Wiley. pp. 17-18.
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